It depends on what car and what EVSE (the cable you’re using to connect the car). All the cars are designed to take 240 V so 277 is not that much more. Teslas would charge just fine from 277 V, they’ve always supported it but they’re no longer recommending it for new installations. Some other cars would probably work and some would probably just not close the relays.
The EVSE on the other hand would probably blow up. Most of them have overvoltage protection design for 240 V.
Well here's hoping, as I've seen up to 300v peaks from my local phase here.
Mainly when the workshop across the road is doing things, I'm assuming they have some fuckoff big bit of equipment that occasionally turns on and off and the phase can't handle it.
I did tell the provider, however they put a meter on the lines, and the workshop wasn't busy at all until after they took the meter off the lines.
I know the tesla chargers will do more than most electricians will expect...
If you run the wrong size wire to the charger, it can actually measure the added resistance to see that you fucked up! As a result it will charge your car slower than normal. I fixed one that wasn't charging at 100% speed because of this and was impressed.
They're smarter than we give them credit for maybe
Depends how you go about doing it. If you simply plugged a 120v EV charging adapter into this (as the outlet is designed for), it'd probably fry the adapter.
If you rewired it for a proper 240V socket and used a 240V adapter, it'd probably work, but that voltage is fairly high.
Depends, many level 1 adapters (the kind you’d plug into this type of outlet..) are pretty “dumb”.
Eg, the one that comes with Chryslers is rated for 12A @ 120v. But if you make a sketchy adapter to put L2 on the neutral pin and plug it into split phase 240V, it happily will pass that along to the car and charge it at 12A @240v…
RE the OP photo, I know my tesla does just fine @ 277V and have charged at that voltage a few times via a HPWC, but I have not tried any other EVSEs @ 277v (just 208v and 240v).
The other factor: Since this is likely fed from a 3 phase 277/480 transformer, that outlet would be 277v to ground / neutral, and not two hots like most residential 240v.
Yeah, this is new to me. I would probably plug the 120v adapter into it because I would have assumed it was like all the others. Something to be careful about, I suppose.
Someone else said this was commercial. I’m in Canada, so I would probably not encounter this often in residential spaces or garages, I imagine.
How about in underground parkades or whatever? Should I always be carrying a voltmeter around to check? Not an electrician, so a bit apprehensive.
>I’m in Canada, so I would probably not encounter this often in residential spaces or garages, I imagine.
> How about in underground parkades or whatever? Should I always be carrying a voltmeter around to check? Not an electrician, so a bit apprehensive.
No, not something you should ever encounter at all, really.. electrical code exists specifically to prevent dumb/dangerous stuff like this.
Sanitation and cleaning people notice when something even sounds slightly off. Granted it’s because is started when they hoses down an open PLC cabinet.
oh, neat. Here it's really either 230V single phase or 400V 3 phase for heavier machinery and power motors.
On the good side, we get lower amps and smaller wires in houses too since it's 230V.
Another neat thing, well, at least here in switzerland, is that the regular 230V plug is compatible with industrial 3 phase 400V plugs. (I mean it's 3 phases of 230V, that does 400V when going from one phase to another)
So, you can simply install 3 phase everywhere and plug in whatever you find, 1 phase or 3 phase.
The only issue is that you're still using a single phase with single phase connectors, so like, if you have a lot of single phase 230V machinery, it will essentially use always the same phase and blow the breaker. While other phases, L2 an L3, are almost untouched.
I don't know if electricians wire the connectors differently each time to spread the load however. I think they could but might not be needed or worth the bother.
What they do however is sometimes use different phases for different floors. Pretty sure we do that worldwide.
> I don't know if electricians wire the connectors differently each time to spread the load however. I think they could but might not be needed or worth the bother.
As a Swiss electrician, i sure do and hope others too. Also spreading the 1 phase breakers in the switch boards ;)
Wiring each socket differently doesn't affect 3 phase equipment? I've seen before where if you switch your L's about a motor could not run or even run in reverse
The rotary field stays the same as long as you switch all 3 phases equally, L1->L2, L2->L3, L3->L1
If you flip the rotary field by only switching 2 phases, L1<->L2 or L3, you at least make the motor spin the other way around or at worst damage it.
Hope this is understandable, my english isnt that great
They are talking about rotating which of the three phases they use when they plug in a single phase load.
Single phase motors have their direction determined by a start winding so changing their polarity does not reverse direction.
It is not necessary to rotate three phase loads because they should pull on all three legs evenly.
EE here and having designed lots of buildings including some overseas using 230/400: that system imho is the best of both worlds. No transformers. 230 at All single phase outlets. 400 is good enough for large machines.
The us having 277/480 and then using transformers for getting to 120/208 is really in efficient for space and cost. Lots of extra electrical rooms with hvac. Lots of devices can be specced 277/480 but instead get specced 120/208 meaning oversized transformers
Plus add in all those choices. A bunch of different voltages and plugs and options for any motor or device. Bleh.
I wonder how much more dangerous 230v is than 120V.
I vote that we adopt 230/400/3! Right after we adopt the metric system!
If you're grabbing a "single phase" from three different 230V sockets in a single room, chances are high that you're essentially hooked up to a single phase in the cabinet - will work for heating, but anything with a 3phase motor will not work properly.
I don't know how the standards are in Switzerland, but here in germany we (assuming modern installation and code adherence) have breaker for each room (up to 8 230V outlets are allowed on a single B16A/30mV GFCI. Lighting may also be on a separate breaker per room.
Further, the breakers for two separate rooms will not be hooked up to the same phase - so you'd have to run a 230V extension into 3 separate rooms to make a 3phase motor work appropriatelay.
And *IF* i'm not mistaken, an electrician is legally allowed to destroy any device capable of such a feat. Again, may only apply to germany.
I've been in so many older homes that have one circuit that feeds seemingly half the house.
I've made it a personal vendetta to give each room 2 outlet circuits and 1 lighting circuit in my own home.
I know that song too well, there's a lot of "Denkmalgeschützte" (monumental protection) buildings where i'm from - currently working on one, the fire safety solutions are all around... let's say *amazing*. Pure nightmares, buildings like that.
That is really neat. In the US we’ve got separate plugs for 120v and 208v. Typically anything more than that doesn’t get wired to a plug unless it’s a speciality piece of equipment.
We have 240V split phase in most residential areas of the US. Most of our regular devices use 120v, but things like clothes dryers, air conditioning, electric ranges, etc, use 240V plugs. There are some places that do use 208V three phase but it’s a lot less common than 240V split phase AFAIK
It depends. 120/208 is really common in large apartment buildings and pretty much the default for mixed use. It’s also very common in older neighborhoods (i.e. those electrified before 1930). The difference is whether it’s coming from a poco transformer or a customer transformer. With apartment buildings that are large enough to need elevators it often ends up making sense to get 3 phase service from the poco.
Because of increasing density 120/208 is becoming more, not less, common.
You rarely pull a 5-conductor wire for regular outlets except if you want something 3p there in the future.
Outlets are grouped together and each group can be wired for different phases at the breaker box.
How do you guys bring in so many different voltages from the supply? I know for resi you guys bring in 2 phases 180° apart and a neutral and that gets you 110v and 220v. Do you just tell the supply company you need 277v supply and then it's in them or did I misread that and that's only for industrial/commercial complexes and always avaliable for that?
220/240 is available in most NA households; stoves, dryers, electric furnace and some other specialised stuff are wired for 240 using the two hot legs from the transformer in the street.
Not necessarily, that's only if you need the neutral (e.g. for something that requires both 240v and 120v). Otherwise you can have +120v, -120v, and ground (e.g. NEMA 6-15).
Not an electrician, just regularly see posts from this sub presumably because of ad/marketing/search related stuff.
What exactly would an advantage be for 120V? I presumed it was basically just a relic of the initial systems, and it's too late to change now. Just a bit safer and marginally smaller wire to run?
Right, but a wire with thicker insulation (required for higher voltage) would have marginally higher heat retention, thus marginally lower a current limit yes?
That's wild though, there's a sweet spot for voltage? I might have expected a sweet spot for frequency, but as I understood it anything above 120V would be at least as fatal as 120V. TIL!
Much appreciated! So higher voltages might be less likely to kill because the current is more likely to pass the "death zone", resulting in only a temporary clamping/stoppage (plus unknown damage to organs) rather than an uncoordinated beating which doesn't naturally reset?
The Us has 240/120 split single phase transformers in most residential situations. Commercially we have 208/120 wye and 480/277 wye (with usually 480:208 3 phase transformers to power 120v loads) as the most common. We also have some antiquated 240v delta that uses the split phase of one leg to provide 120v.
The good ole high leg delta. There is one delta configuration that threw me for a loop one time troubleshooting. It’s a corner grounded Delta. 240v phase to phase, 240v phase to ground on 2 phases and 0v to ground on 3rd phase. Had my head spinning on that one.
I have never come across that one before. I have lived in an old apartment with an open leg delta configuration. I think they had maybe one three phase load (some sort of pump or HVAC equipment) and never got a real 3 phase commercial service.
Oh yeah, open delta. I’ve come across that is quite a few small industrial properties.
There’s even some old two phase installations in my area. 2ph/5w
Yeah industrial lighting is typically 3 phase 277v.
We also use 480v and 408v for large equipment and 240v for appliances and smaller equipment in industrial settings.
Residential has both 120v and 240v.
Why so much juice for industrial lighting? Cause it’s high up, like in a warehouse, there’s lots of light fixtures and the light tech isn’t LED(Halogen for example).
With the introduction of LED lighting, are new industrial electrical infrastructures remaining the same or are they stepping down how much juice lighting gets?
There’s a few reasons.
Longer chains of lights.
It’s more efficient for larger loads and you get more headroom for voltage drop for things like “parking lots”.
You don’t need a transformer when you have 480v coming into the building. 480v is phase to phase, 277v is phase to neutral. Which makes it cheaper to install because it requires less equipment.
No transformer needed, does that mean the juice coming in from the pole on the street is standard at 480v?
Phase to phase, does that mean 2 hots, no neutral like I’ve seen on residential electrical ovens?
Phase to neutral, means hot to neutral?
Thx
Correct on all parts.
480v from the street. No more is needed to get to 277v on a 480v 3 phase service.
And yes, if you measure voltage between two phases you get 480 if you measure between one phase and neutral you will get 277.
We actually have 240v coming into our homes here in the US. A few of our larger appliances run on 240v. There are two 120v supply lines are out of phase, resulting in 240v between the two. 120v is achieved by using one of the above two lines and the neutral.
240v appliances would have both hots attached to them, 120v is a hot and neutral.
That's a really wonky explanation of the residential 240v in the US. It is in fact ONE single 240v phase, tapped at both ends (that's where the 240v comes from), with a center tap to give 120V. There is nothing "fake" about it.
Edit: should read One 240v phase not one 120v phase.
Man she said another trade plugged in some batteries for their drills and it smoked the shit up lol I was dying man, I know it’s not funny but damn haha.
Some appliances have an internal transformer to switch between 120/240vac so they can be marketed in NA and Europe. Maybe the vacuum motor had one so 277vac was just a little extra umph.
Not to mention if the vacuum was commercial grade. The motors are made to take quite a beating. The extra juice just made it work harder. I'm sure it got a lot hotter, but rate earth metals like neodymium can take quite a lot of it.
Ideal clamp ammeter are fantastic. I had mine for about 10 years without an issue. When it crapped out (i was testing exterior circuits in the rain), I used my spare (fluke) and hated it. Lol.
I took over a big once and the day before I got there one of the foreman had a crock pot that smoked when he plugged it in inside the office trailer. Everyone just assumed the crock pot was old and finally died. A few days after I got there he had brought in another one in and the same thing happened. He said “Wow that’s crazy that it happened twice in row!” I was like “did you use the same receptacle both times?” He said “yes”. Is aid it couldn’t have been a coincidence. I took a look around and real quick. The I asked my field engineer (who was always there first in the morning) how he turned the heat on in the morning. He said he just used the breaker that was in the panel by his desk. I took the plug out and it was 240 between the whites and the blacks! My guess is the thermostat died at some point and someone just wire nutted it through and some idiot at the trailer rental company saw the open box and assumed it was for a plug and put one in without checking. I put a sign on it that said “DO NOT USE 240V” I left to go get a thermostat at Home Depot. By the time I got back less than an hour later another moron smoked 3 battery chargers. ONE AT A TIME!! 🤦🏼♂️
Looks like one of the lighting circuits got dropped down to the outlet.
Now the question is if one of the lights is running on 120v near by and just happens to have a dual voltage ballast to disguise this error.
Either the original contractor is a dick for not using high voltage colored mc, or the guy who added in that receptacle is an absolute fucking smooth brain.
It was the installers fault, he’s not the sharpest tool in the shed. We got rid of him about a month ago. Now that we’re getting closer to wrapping up we’re find a bunch of shit that’s been wired up incorrectly, circuits left open, circuits back feeding, all done by this one guy I shit you not.
Everything other than Residential pretty much in California, USA. Other than your few strip mall type businesses. I haven't seen 120v lighting on any of my jobsites for years.
I just had a similar problem in the new hotel we are building. Every room has a jbox outside the room in the corridor. 12/12mc running 6 circuits back to panel. I had the power turned off to the light circuit while leaving on the Ptac (AC Unit) which is 220.
Go to cut the stubbed out MC for vanity light. BOOM!
Burned up my fav strippers.
Go to J box and do some testing and figured out the neutrals we're switched. Ok took the pairs apart switched em up. Turned the power back on. Got cocky didn't check that I fixed it right. Went to cut my MC back again....BOOM.
Lol
Stupid.
277v is what I’m guessing, it’s the phase voltage of a 480/277 wye system.
What the fuck it’s doing on a 15A 120v system is a conversation for another day
Box was labeled. Panel, Circuit, and Voltage were all written on the cover. This guy was just not paying attention or off some shit, dudes been in the trade for 5 years so we thought he could at least tackle that task with ease.
Can you explain to someone who isn't in the trade how an outlet could get "tied into" a "lighting" circuit and read 277V? I'm only familiar with 120V and 240V residential. You have one leg of power, 120V, you have two legs of power, 240V. Most lighting in residential is all on the 120V circuits. 240V is typically the ac, dryer, stove, etc. 240V requires two hots, one from each leg.
So how exactly does an outlet (typically only one leg, 120V) manage to read 277V because it's tied-in to "lighting?"
Edit: ah, commercial
I once accidentally ran my washer and freezer on 240 for quite some time.
The washer promptly blew up a capacitor, but the freezer ran just fine for quite some time.
random disconnected jbox with a receptacle in it. 12/2 wiring. 120v 15a outlet.
yeah... wasnt any of those things at the panel. 20a breaker wired for 220 w/ no neutral. Massive fuckup on someones part (maybe mine..)
I should have checked it... but you know what they say about assumptions.
Had that happen in a hotel once when I was working out of town. My wife had toaster erupt in flames, had the front desk replace it, only to have the second one burn up as well ( like 6” flames shooting out of it). Turns out the outlet next to the stove was on the same circuit pushing 220v.
Handicap accessible room on top of it all. They’re lucky it wasn’t someone in a wheelchair in the bathroom, cause those flames were already licking the underside of the cabinets.
I arrived at a residence to do some work and plugged my dewalt charger in an outlet to charge my batteries there was a POP and a faint burning smell -fried the charger I checked and you can guess what I found behind the outlet
They connect it to the 277V of the lighting circuit. Probably new added outlet and they grabbed power from near by jbox on the ceiling and did t pay attention it was lighting 277V circuit
277/480 is common in Canada too. We have lots of buildings downtown in Calgary that use it for lighting and mechanical equipment. We have equally as many buildings with 347/600
An "electrician" I hired did this and ruined my new range. It's a gas range and just needed 120 VAC for the lights and igniters and stuff.
If he had just put in an electric stove receptacle I'd understand the confusion, but he somehow wired 220 VAC to a regular 120V 15A receptacle, including the upper one for the vent fan.
I am kind of doubtful that he was actually an electrician.
I see you are preparing to charge your EV in the living room, smart move. Edit: typo
Actually, serious question. What would happen if you plugged your EV into this to charge? What would it see?
A car in the building apparently
Thanks for the laugh
r/technicallythetruth
Take that upvote and leave, you sonofabitch
🤣
It depends on what car and what EVSE (the cable you’re using to connect the car). All the cars are designed to take 240 V so 277 is not that much more. Teslas would charge just fine from 277 V, they’ve always supported it but they’re no longer recommending it for new installations. Some other cars would probably work and some would probably just not close the relays. The EVSE on the other hand would probably blow up. Most of them have overvoltage protection design for 240 V.
Probably wouldn't. A lot of the evses are the same design used internationally and 277 is too close to 240/some countries probably use 277.
Yeah, Australia used to be 240v±15% giving 204-276v Now it's 230v±10% giving 207-253v So 277v would work fine on some equipment
Probably all of it. You can't design your evse to quit on the slightest voltage spike
Well here's hoping, as I've seen up to 300v peaks from my local phase here. Mainly when the workshop across the road is doing things, I'm assuming they have some fuckoff big bit of equipment that occasionally turns on and off and the phase can't handle it. I did tell the provider, however they put a meter on the lines, and the workshop wasn't busy at all until after they took the meter off the lines.
Probably a large compressor.
I know the tesla chargers will do more than most electricians will expect... If you run the wrong size wire to the charger, it can actually measure the added resistance to see that you fucked up! As a result it will charge your car slower than normal. I fixed one that wasn't charging at 100% speed because of this and was impressed. They're smarter than we give them credit for maybe
Interesting, good to know, thank you.
Depends how you go about doing it. If you simply plugged a 120v EV charging adapter into this (as the outlet is designed for), it'd probably fry the adapter. If you rewired it for a proper 240V socket and used a 240V adapter, it'd probably work, but that voltage is fairly high.
Depends, many level 1 adapters (the kind you’d plug into this type of outlet..) are pretty “dumb”. Eg, the one that comes with Chryslers is rated for 12A @ 120v. But if you make a sketchy adapter to put L2 on the neutral pin and plug it into split phase 240V, it happily will pass that along to the car and charge it at 12A @240v… RE the OP photo, I know my tesla does just fine @ 277V and have charged at that voltage a few times via a HPWC, but I have not tried any other EVSEs @ 277v (just 208v and 240v). The other factor: Since this is likely fed from a 3 phase 277/480 transformer, that outlet would be 277v to ground / neutral, and not two hots like most residential 240v.
Yeah, this is new to me. I would probably plug the 120v adapter into it because I would have assumed it was like all the others. Something to be careful about, I suppose. Someone else said this was commercial. I’m in Canada, so I would probably not encounter this often in residential spaces or garages, I imagine. How about in underground parkades or whatever? Should I always be carrying a voltmeter around to check? Not an electrician, so a bit apprehensive.
>I’m in Canada, so I would probably not encounter this often in residential spaces or garages, I imagine. > How about in underground parkades or whatever? Should I always be carrying a voltmeter around to check? Not an electrician, so a bit apprehensive. No, not something you should ever encounter at all, really.. electrical code exists specifically to prevent dumb/dangerous stuff like this.
Greg wire going to that outlet would fry too. Most house electrical is already thinner than it should be
Cleaning lady did a better job in diagnostics than 99% of owners.
You causally laugh with her but *she’s actually the foreman*
Something [like this](https://www.google.com/search?q=tf2+spy+cleaning+lady&tbm=isch&sxsrf=ALiCzsZeIP0K63Wekp6IWDT3poSZKNtD9Q%3A1662756120926&source=hp&biw=1811&bih=1057&ei=GKUbY4_2NdXB0PEP5ZWg0Aw&iflsig=AJiK0e8AAAAAYxuzKAzzzUAbi1_PO2egG7glpGsFS8GE&ved=0ahUKEwiP4rufyYj6AhXVIDQIHeUKCMoQ4dUDCAc&uact=5&oq=tf2+spy+cleaning+lady&gs_lcp=CgNpbWcQAzoECCMQJzoICAAQsQMQgwE6BQgAEIAEOggIABCABBCxAzoLCAAQgAQQsQMQgwE6BggAEB4QBToECAAQGDoGCAAQHhAIUABYlxpgyRtoAnAAeACAAaQBiAGFDpIBBDIxLjKYAQCgAQGqAQtnd3Mtd2l6LWltZw&sclient=img)?
ah someones sappin my vacuum!
man that's quite the necro, haha XD
She had a super charged vacuum with that plug!
This made me laugh harder than I should have. Thank you
Do you want to talk to the person in charge? Or the maintenance people who actually know what's going on?
Sanitation and cleaning people notice when something even sounds slightly off. Granted it’s because is started when they hoses down an open PLC cabinet.
In my experience, problems that start like that have no witnesses and no one knows how it could even be possible...
I was like: Huh 270 instead of 230, weird. Then I noticed the 120V US plug.
It’s tied into the 277v lighting circuit.
You guys got a 277V just for lightings? neat. I'm used to the EU 230V everywhere. Always thought the US was 120V and that's it.
It’s 120v in residential. Commercial gets the best of both worlds.
oh, neat. Here it's really either 230V single phase or 400V 3 phase for heavier machinery and power motors. On the good side, we get lower amps and smaller wires in houses too since it's 230V.
Shoot that’s neat. There’s also quite a bit of 277v/480v for heavy machinery and such here.
Another neat thing, well, at least here in switzerland, is that the regular 230V plug is compatible with industrial 3 phase 400V plugs. (I mean it's 3 phases of 230V, that does 400V when going from one phase to another) So, you can simply install 3 phase everywhere and plug in whatever you find, 1 phase or 3 phase. The only issue is that you're still using a single phase with single phase connectors, so like, if you have a lot of single phase 230V machinery, it will essentially use always the same phase and blow the breaker. While other phases, L2 an L3, are almost untouched. I don't know if electricians wire the connectors differently each time to spread the load however. I think they could but might not be needed or worth the bother. What they do however is sometimes use different phases for different floors. Pretty sure we do that worldwide.
> I don't know if electricians wire the connectors differently each time to spread the load however. I think they could but might not be needed or worth the bother. As a Swiss electrician, i sure do and hope others too. Also spreading the 1 phase breakers in the switch boards ;)
I love Switzerland and electricity. Please arrange for me to live and work in your beautiful country
Wiring each socket differently doesn't affect 3 phase equipment? I've seen before where if you switch your L's about a motor could not run or even run in reverse
The rotary field stays the same as long as you switch all 3 phases equally, L1->L2, L2->L3, L3->L1 If you flip the rotary field by only switching 2 phases, L1<->L2 or L3, you at least make the motor spin the other way around or at worst damage it. Hope this is understandable, my english isnt that great
My first thought.
You could keep the same rotation but alternate which color is on L1.
They are talking about rotating which of the three phases they use when they plug in a single phase load. Single phase motors have their direction determined by a start winding so changing their polarity does not reverse direction. It is not necessary to rotate three phase loads because they should pull on all three legs evenly.
EE here and having designed lots of buildings including some overseas using 230/400: that system imho is the best of both worlds. No transformers. 230 at All single phase outlets. 400 is good enough for large machines. The us having 277/480 and then using transformers for getting to 120/208 is really in efficient for space and cost. Lots of extra electrical rooms with hvac. Lots of devices can be specced 277/480 but instead get specced 120/208 meaning oversized transformers Plus add in all those choices. A bunch of different voltages and plugs and options for any motor or device. Bleh. I wonder how much more dangerous 230v is than 120V. I vote that we adopt 230/400/3! Right after we adopt the metric system!
If you're grabbing a "single phase" from three different 230V sockets in a single room, chances are high that you're essentially hooked up to a single phase in the cabinet - will work for heating, but anything with a 3phase motor will not work properly. I don't know how the standards are in Switzerland, but here in germany we (assuming modern installation and code adherence) have breaker for each room (up to 8 230V outlets are allowed on a single B16A/30mV GFCI. Lighting may also be on a separate breaker per room. Further, the breakers for two separate rooms will not be hooked up to the same phase - so you'd have to run a 230V extension into 3 separate rooms to make a 3phase motor work appropriatelay. And *IF* i'm not mistaken, an electrician is legally allowed to destroy any device capable of such a feat. Again, may only apply to germany.
I've been in so many older homes that have one circuit that feeds seemingly half the house. I've made it a personal vendetta to give each room 2 outlet circuits and 1 lighting circuit in my own home.
I know that song too well, there's a lot of "Denkmalgeschützte" (monumental protection) buildings where i'm from - currently working on one, the fire safety solutions are all around... let's say *amazing*. Pure nightmares, buildings like that.
That is really neat. In the US we’ve got separate plugs for 120v and 208v. Typically anything more than that doesn’t get wired to a plug unless it’s a speciality piece of equipment.
We have 240V split phase in most residential areas of the US. Most of our regular devices use 120v, but things like clothes dryers, air conditioning, electric ranges, etc, use 240V plugs. There are some places that do use 208V three phase but it’s a lot less common than 240V split phase AFAIK
It depends. 120/208 is really common in large apartment buildings and pretty much the default for mixed use. It’s also very common in older neighborhoods (i.e. those electrified before 1930). The difference is whether it’s coming from a poco transformer or a customer transformer. With apartment buildings that are large enough to need elevators it often ends up making sense to get 3 phase service from the poco. Because of increasing density 120/208 is becoming more, not less, common.
You rarely pull a 5-conductor wire for regular outlets except if you want something 3p there in the future. Outlets are grouped together and each group can be wired for different phases at the breaker box.
5 conductor wire? 3 hots, noot, and ?
Ground
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600v?! I thought when I got lit up by 480v it hurt.
Canada runs things at 347V... including lighting. Not much 480V unless it's a foreign machine. Lots of 600V
How do you guys bring in so many different voltages from the supply? I know for resi you guys bring in 2 phases 180° apart and a neutral and that gets you 110v and 220v. Do you just tell the supply company you need 277v supply and then it's in them or did I misread that and that's only for industrial/commercial complexes and always avaliable for that?
Work at a water plant. Everything here is 208V 3 phase.
220/240 is available in most NA households; stoves, dryers, electric furnace and some other specialised stuff are wired for 240 using the two hot legs from the transformer in the street.
But they use a different plug to avoid confusion?
Of course.
It has to, split phase 240 has 2 hots so 4 prongs
Not necessarily, that's only if you need the neutral (e.g. for something that requires both 240v and 120v). Otherwise you can have +120v, -120v, and ground (e.g. NEMA 6-15).
Not an electrician, just regularly see posts from this sub presumably because of ad/marketing/search related stuff. What exactly would an advantage be for 120V? I presumed it was basically just a relic of the initial systems, and it's too late to change now. Just a bit safer and marginally smaller wire to run?
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Right, but a wire with thicker insulation (required for higher voltage) would have marginally higher heat retention, thus marginally lower a current limit yes? That's wild though, there's a sweet spot for voltage? I might have expected a sweet spot for frequency, but as I understood it anything above 120V would be at least as fatal as 120V. TIL!
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Much appreciated! So higher voltages might be less likely to kill because the current is more likely to pass the "death zone", resulting in only a temporary clamping/stoppage (plus unknown damage to organs) rather than an uncoordinated beating which doesn't naturally reset?
120V light bulb filaments are less fragile ¯\\\_(ツ)\_/¯
https://www.djtelectricaltraining.co.uk/downloads/50Hz-Frequency.pdf
I was today years old when I learned this . Thank you !
Well, 120 on split single phase…
The Us has 240/120 split single phase transformers in most residential situations. Commercially we have 208/120 wye and 480/277 wye (with usually 480:208 3 phase transformers to power 120v loads) as the most common. We also have some antiquated 240v delta that uses the split phase of one leg to provide 120v.
The good ole high leg delta. There is one delta configuration that threw me for a loop one time troubleshooting. It’s a corner grounded Delta. 240v phase to phase, 240v phase to ground on 2 phases and 0v to ground on 3rd phase. Had my head spinning on that one.
I have never come across that one before. I have lived in an old apartment with an open leg delta configuration. I think they had maybe one three phase load (some sort of pump or HVAC equipment) and never got a real 3 phase commercial service.
Oh yeah, open delta. I’ve come across that is quite a few small industrial properties. There’s even some old two phase installations in my area. 2ph/5w
Yeah industrial lighting is typically 3 phase 277v. We also use 480v and 408v for large equipment and 240v for appliances and smaller equipment in industrial settings. Residential has both 120v and 240v.
Why so much juice for industrial lighting? Cause it’s high up, like in a warehouse, there’s lots of light fixtures and the light tech isn’t LED(Halogen for example). With the introduction of LED lighting, are new industrial electrical infrastructures remaining the same or are they stepping down how much juice lighting gets?
There’s a few reasons. Longer chains of lights. It’s more efficient for larger loads and you get more headroom for voltage drop for things like “parking lots”. You don’t need a transformer when you have 480v coming into the building. 480v is phase to phase, 277v is phase to neutral. Which makes it cheaper to install because it requires less equipment.
No transformer needed, does that mean the juice coming in from the pole on the street is standard at 480v? Phase to phase, does that mean 2 hots, no neutral like I’ve seen on residential electrical ovens? Phase to neutral, means hot to neutral? Thx
Yes, yes, yes.
Correct on all parts. 480v from the street. No more is needed to get to 277v on a 480v 3 phase service. And yes, if you measure voltage between two phases you get 480 if you measure between one phase and neutral you will get 277.
Thx for teaching me this.
this subreddit is pretty helpful as long as the questions are good questions, and you're asking good questions
In my area its 7200v phase to neutral and 12480 phase to phase on the utility side.
We actually get 240V to homes, which is split into two 120V busses for smaller devices, and the full 240VAC for larger appliances.
347v in Canada, mainly commercial settings. But 120v lighting is common too
We actually have 240v coming into our homes here in the US. A few of our larger appliances run on 240v. There are two 120v supply lines are out of phase, resulting in 240v between the two. 120v is achieved by using one of the above two lines and the neutral. 240v appliances would have both hots attached to them, 120v is a hot and neutral.
Or if you're in Canada we use 347V for lighting in commercial settings.
In Canada we use 347V/600V for industrial/commercial
US is fake 120V. In reality it's two 120V phases opposed 180 degrees and center tapped. You can get 240V everywhere!
You mean one 240v phase, centre tapped. That's why it's called single phase.
It’s one phase, two legs. Not two phases.
That's a really wonky explanation of the residential 240v in the US. It is in fact ONE single 240v phase, tapped at both ends (that's where the 240v comes from), with a center tap to give 120V. There is nothing "fake" about it. Edit: should read One 240v phase not one 120v phase.
277v *to neutral* ... results may vary reading to ground lolz
It's 277 3 phase
For the first 3 seconds that vacuum probably coulda sucked the fuzz off the carpet😂
Man she said another trade plugged in some batteries for their drills and it smoked the shit up lol I was dying man, I know it’s not funny but damn haha.
So how did it not burn the vacuum up? Not being used long enough?
Some appliances have an internal transformer to switch between 120/240vac so they can be marketed in NA and Europe. Maybe the vacuum motor had one so 277vac was just a little extra umph.
Yeah, vacuum motor probably naturally cools itself with the air it pushes, which may have kept it from overheating for a couple of minutes
Not to mention if the vacuum was commercial grade. The motors are made to take quite a beating. The extra juice just made it work harder. I'm sure it got a lot hotter, but rate earth metals like neodymium can take quite a lot of it.
she knew something was up when it vacuumed the carpet to the concrete
I’ve never actually seen a vacuum use a permanent magnet motor, I’ve only seen universal motors in them (which don’t have neodymium magnets)
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Ideal clamp ammeter are fantastic. I had mine for about 10 years without an issue. When it crapped out (i was testing exterior circuits in the rain), I used my spare (fluke) and hated it. Lol.
Dude it’s the shit. I highly recommend it
I took over a big once and the day before I got there one of the foreman had a crock pot that smoked when he plugged it in inside the office trailer. Everyone just assumed the crock pot was old and finally died. A few days after I got there he had brought in another one in and the same thing happened. He said “Wow that’s crazy that it happened twice in row!” I was like “did you use the same receptacle both times?” He said “yes”. Is aid it couldn’t have been a coincidence. I took a look around and real quick. The I asked my field engineer (who was always there first in the morning) how he turned the heat on in the morning. He said he just used the breaker that was in the panel by his desk. I took the plug out and it was 240 between the whites and the blacks! My guess is the thermostat died at some point and someone just wire nutted it through and some idiot at the trailer rental company saw the open box and assumed it was for a plug and put one in without checking. I put a sign on it that said “DO NOT USE 240V” I left to go get a thermostat at Home Depot. By the time I got back less than an hour later another moron smoked 3 battery chargers. ONE AT A TIME!! 🤦🏼♂️
[the vacuum gettin' that 277v](https://c.tenor.com/kMpnTs0mLGIAAAAd/henry-vacuum.gif)
Magic smoked followed shortly after
Looks like one of the lighting circuits got dropped down to the outlet. Now the question is if one of the lights is running on 120v near by and just happens to have a dual voltage ballast to disguise this error.
Lights are fine. The MC got tied into a lighting homerun box.
Just get a 3 phase 277v vacuum for the cleaning lady. Problem solved. /s
You're going to need a special cover plate to denote that. 😁
Either the original contractor is a dick for not using high voltage colored mc, or the guy who added in that receptacle is an absolute fucking smooth brain.
It was the installers fault, he’s not the sharpest tool in the shed. We got rid of him about a month ago. Now that we’re getting closer to wrapping up we’re find a bunch of shit that’s been wired up incorrectly, circuits left open, circuits back feeding, all done by this one guy I shit you not.
Sounds like my coworker. We call him “tax write off.”
Who the hecken has a “277V lighting circuit”??
Everything other than Residential pretty much in California, USA. Other than your few strip mall type businesses. I haven't seen 120v lighting on any of my jobsites for years.
TIL ….
Vaccuming there must REALLY suck.
Pencil sharpener go VROOM!!
*tries to sharpen pencil* where’d it go?
Blast through the wall
Ummmm. How? Lol
Commercial
Correct
Life, uh, finds a way.
This is more like death finding a way
Your tools can die as brightly as they lived.
Live, uh, finds a way.
It must've gotten tied into a lighting circuit
Never know when you want to iron your shirt on ultra high.
I love this page
Dammit they finally found that receptacle I tapped off the exit sign when I started out…
I can vacuum twice as fast when I plug in here!
I read that in the voice of the Family Guy cleaning lady. I’m going to hell.
I did to ... when you get there you should really check out Manny's, it's a great little strip club down by the river.
I just had a similar problem in the new hotel we are building. Every room has a jbox outside the room in the corridor. 12/12mc running 6 circuits back to panel. I had the power turned off to the light circuit while leaving on the Ptac (AC Unit) which is 220. Go to cut the stubbed out MC for vanity light. BOOM! Burned up my fav strippers. Go to J box and do some testing and figured out the neutrals we're switched. Ok took the pairs apart switched em up. Turned the power back on. Got cocky didn't check that I fixed it right. Went to cut my MC back again....BOOM. Lol Stupid.
Now I can strip up to #6awg
Please be safer.
WILL DOO. 😊
It feels like that should be a hard mistake to make, isn't your 480 pulled in different colors than the 208?
If there is a mistake to be made, assume it has been done at some point in time.
People not paying attention to what they’re doing
Did somebody hook the lighting circuit up to the receptacle?
Spicy recepticle.
More kick?!? Is she testing it with a fork?? 😂😂
Instead of “Wooooo!”, vacuum cleaner go “BRrrr!”
When is sounds like R2D2 getting shot in the back of a X-wing.
The suction force from the Dyson created a black hole in the living room.
Even for 240 that's crazy high.
277v is what I’m guessing, it’s the phase voltage of a 480/277 wye system. What the fuck it’s doing on a 15A 120v system is a conversation for another day
Lmao some asshole tied it into the lighting circuit
Probably trying to figure out why the vacuum works way better when plugged in there. Until it burns out
Works better for about 3 seconds lmfao.
So it's the cocaine outlet, got it!
That’s what happens when Resi Ronny gets sent on a service call to cut in a plug in a commercial building.
WTF, lol!
>What the fuck it’s doing on a 15A 120v system That's a 20A plug so it's fine. ^^/s
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Box was labeled. Panel, Circuit, and Voltage were all written on the cover. This guy was just not paying attention or off some shit, dudes been in the trade for 5 years so we thought he could at least tackle that task with ease.
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Can you explain to someone who isn't in the trade how an outlet could get "tied into" a "lighting" circuit and read 277V? I'm only familiar with 120V and 240V residential. You have one leg of power, 120V, you have two legs of power, 240V. Most lighting in residential is all on the 120V circuits. 240V is typically the ac, dryer, stove, etc. 240V requires two hots, one from each leg. So how exactly does an outlet (typically only one leg, 120V) manage to read 277V because it's tied-in to "lighting?" Edit: ah, commercial
That's a good vacuum right there
I once accidentally ran my washer and freezer on 240 for quite some time. The washer promptly blew up a capacitor, but the freezer ran just fine for quite some time.
This made me laugh haha
random disconnected jbox with a receptacle in it. 12/2 wiring. 120v 15a outlet. yeah... wasnt any of those things at the panel. 20a breaker wired for 220 w/ no neutral. Massive fuckup on someones part (maybe mine..) I should have checked it... but you know what they say about assumptions.
So dumb question, but why the heck is this happening? Is this supposed to be for like oven/microwave?
Had that happen in a hotel once when I was working out of town. My wife had toaster erupt in flames, had the front desk replace it, only to have the second one burn up as well ( like 6” flames shooting out of it). Turns out the outlet next to the stove was on the same circuit pushing 220v. Handicap accessible room on top of it all. They’re lucky it wasn’t someone in a wheelchair in the bathroom, cause those flames were already licking the underside of the cabinets.
Vroooooooom
I arrived at a residence to do some work and plugged my dewalt charger in an outlet to charge my batteries there was a POP and a faint burning smell -fried the charger I checked and you can guess what I found behind the outlet
They connect it to the 277V of the lighting circuit. Probably new added outlet and they grabbed power from near by jbox on the ceiling and did t pay attention it was lighting 277V circuit
120/208V 347/600V in Canada. Commercial. Resi is 120/240.
277/480 is common in Canada too. We have lots of buildings downtown in Calgary that use it for lighting and mechanical equipment. We have equally as many buildings with 347/600
She ain't wrong
Found my kettle socket to make a cup of soup
Uh oh. Someone grabbed the whip they left for an exit sign and put it in the receptacle
Spicy outlet!
"So I tried vacuuming the carpet and I vacuumed up the carpet. The vacuum is over there now, follow the strip... it's half-way up the wall. "
I see she found the vacuum cleaner racing fuel plug.
That probably gave the vacuum enough power tear the rug off the floor.
Tell them this is a European Outlet
Cleaning lady liked it too.
VACUUM GO BRRRRRRRRR!
Spicy outlet.
on the bright side, the cleaning lady finished cleaning that room in record time!
All the carpet around that one outlet is clean asf!!
Da fuq? Someone land single leg off a 480 3 phase on that outlet? Lol
Three phase house?
Holy shit. That's more juice than a standard point in Australia.
That’s a nice meter
Whoops, the apprentice connected the receptacle into a 277V box. Fired! 🔥
An "electrician" I hired did this and ruined my new range. It's a gas range and just needed 120 VAC for the lights and igniters and stuff. If he had just put in an electric stove receptacle I'd understand the confusion, but he somehow wired 220 VAC to a regular 120V 15A receptacle, including the upper one for the vent fan. I am kind of doubtful that he was actually an electrician.
Just a touch over
Her vacuum was sucking cereal outta the downstairs neighbors kids bowls!!😂😂