# 120v 277v ?!



## MollyHatchet29

120 for power and 277 for lighting? There's these things called subpanels and transformers that make all this possible. 120v and 277v circuits are fed from different panels.


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## Theriot

Xformer to step down. Unlikely step up. And a little magic


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## Mcsparkin

*thx*

Really appreciate it! correct me if I'm wrong- the main is 277/480 and then through a breaker to the step-down transformer and finally to the 120/xxx sub-panel. This raises a new question; Is the sub-panel in this case 3p or single? 120/208 or 120/240? thanks again.


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## walkerj

Mcsparkin said:


> Really appreciate it! correct me if I'm wrong- the main is 277/480 and then through a breaker to the step-down transformer and finally to the 120/xxx sub-panel. This raises a new question; Is the sub-panel in this case 3p or single? 120/208 or 120/240? thanks again.


Depends


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## running dummy

Most of the buildings I've worked in with your situation will supply a 120/208v panel for receptacle type loads.


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## icefalkon

Most likely it's a 3 pole from the step down transformer for the 120/208V receptacles loads.

Steve from NYC


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## greenman

That is not a normal voltage for Canada...
So you would have two main feeds or a substation to split the different system voltages. The norm is 120/208/240v or 347/600v.
Some factory use 277/480v for machines that come from another country.(like Japan).


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## BBQ

Mcsparkin said:


> I'm confused about something that will seem very simple to most of you. At the building we are working in, there is 120v as well as 277v ...My question is; Is there 2 separate systems that make this possible? I am aware of 120/240, 120/208 3p/, 277/480 3p BUT I am unable to figure this out. Please help!


Here in the US a 480Y/277 volt electrical service is very common, almost any building of good size in my area will have a 480Y/277 volt service and that will be used to supply as much of the loads as possible, motors, machinery, lighting etc. Then we will install transformers and panels to make 480 into 208Y/120 volt for the general purpose power.

In Canada I am not sure what is common, I know you guys use 600Y/347 for a lot of things.

It sounds like in your building they needed some 480Y/277 so a transformer was installed to either step 600 volts down or 208 volts up depending on the buildings service voltage. That is unless your power companies offer a 480Y/277 service)


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## RGH

Read your theory book delta and y ...y configuration is very useful and common, both act differently currant wise...as far as increasing voltages and currants....y is more versatile than say 480delta config......read this stuff...learn it...trust me kid...you'll need to know and understand it..


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## Vintage Sounds

Seems like there are some parts of Canada where the utility supplies 277/480 instead of 347/600v.


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## Mcsparkin

With a little more guidance and understanding by the cool people I work with, I was able to figure this out and it was just as simple as you guys said! I hope the best for everyone that cared to help!


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