# 240V on 208V



## electricalcj (Feb 9, 2011)

electricalcj said:


> Hat will a 240V line do to a 208V panel. If anything.


I meant what will.


----------



## JRaef (Mar 23, 2009)

So assuming 3 phase, the issue is that a 240V 3 phase 4 wire system cannot have 1 pole breakers on the high leg. A 3 phase panel designed for 120/240 4 wire will have mechanical provisions that prevent this, a 120/208V 4 wire panel will not.


----------



## Bulldog1 (Oct 21, 2011)

JRaef said:


> So assuming 3 phase, the issue is that a 240V 3 phase 4 wire system cannot have 1 pole breakers on the high leg. A 3 phase panel designed for 120/240 4 wire will have mechanical provisions that prevent this, a 120/208V 4 wire panel will not.



All the 3 phase panels I have seen and installed are rated 120/240. We use them on 120/208 systems and 120/240 delta highlegs. I know you have heard how some clueless guy put 120V equipment on the highleg and smoked it. Never seen a panel that would not allow single pole breakers on b phase.


----------



## SteveO. (Oct 17, 2011)

Bulldog1 said:


> All the 3 phase panels I have seen and installed are rated 120/240. We use them on 120/208 systems and 120/240 delta highlegs. I know you have heard how some clueless guy put 120V equipment on the highleg and smoked it. Never seen a panel that would not allow single pole breakers on b phase.


In Canada all 4 wire Delta systems have to use a panel that doesn't allow the neutral and the B phase to be connected to a single pole breaker and have to be marked as having a high leg. It's got a single phase section with a neutral bar and the three phase section has no neutral bar. Code requires the high leg to always be the "B" phase as well. I'll get a photo of one if you'd like, we have one here.


----------



## Bulldog1 (Oct 21, 2011)

SteveO. said:


> In Canada all 4 wire Delta systems have to use a panel that doesn't allow the neutral and the B phase to be connected to a single pole breaker and have to be marked as having a high leg. It's got a single phase section with a neutral bar and the three phase section has no neutral bar. Code requires the high leg to always be the "B" phase as well. I'll get a photo of one if you'd like, we have one here.



The OP is in the USA.


----------



## di11igaf (Jan 1, 2012)

electricalcj said:


> Hat will a 240V line do to a 208V panel. If anything.


Nothing, panel/breakers should be rated for 250v anyway.


----------



## Dennis Alwon (May 9, 2009)

electricalcj said:


> What will a 240V line do to a 208V panel. If anything.


What are you asking. If a panel is rated 208V-- which would be unusual then you cannot serve it with a 240V line. What would happen is probably nothing but it would not be compliant. As stated most panels are rated for 250V so 208 would be fine.

Now if you are talking about a motor control panel then we have a different issue.


----------



## SteveO. (Oct 17, 2011)

Bulldog1 said:


> The OP is in the USA.


I know, I was just commenting on what you said here:



Bulldog1 said:


> Never seen a panel that would not allow single pole breakers on b phase.


 I think it's odd for someone not to have seen a panel like that when all the 4 wire delta stuff is like that here. :thumbsup:


----------



## Bulldog1 (Oct 21, 2011)

SteveO. said:


> I know, I was just commenting on what you said here:
> 
> 
> 
> I think it's odd for someone not to have seen a panel like that when all the 4 wire delta stuff is like that here. :thumbsup:




We don't have them in the USA as far as I know. :thumbsup:


----------



## Vintage Sounds (Oct 23, 2009)

SteveO. said:


> In Canada all 4 wire Delta systems have to use a panel that doesn't allow the neutral and the B phase to be connected to a single pole breaker and have to be marked as having a high leg. It's got a single phase section with a neutral bar and the three phase section has no neutral bar. Code requires the high leg to always be the "B" phase as well. I'll get a photo of one if you'd like, we have one here.


Well I wouldn't mind a picture because I didn't know such panels existed. Who makes them? I know of the code rule preventing this though and I always figured in that situation you would use a 3 phase panel without running a neutral to it, and have a second, single phase 120/240 panel for 120 loads. . Above all though I didn't know people even used the 4 wire delta in Canada. Where would anyone install a 600v to 120/240 delta transformer? Why?

Sent from my iPhone using ET Forum


----------



## jefft110 (Jul 7, 2010)

Bulldog1 said:


> All the 3 phase panels I have seen and installed are rated 120/240. We use them on 120/208 systems and 120/240 delta highlegs. *I know you have heard how some clueless guy put 120V equipment on the highleg and smoked it.* Never seen a panel that would not allow single pole breakers on b phase.



If you've never done that by accident, then you haven't worked much with a delta.


----------



## Bulldog1 (Oct 21, 2011)

jefft110 said:


> If you've never done that by accident, then you haven't worked much with a delta.



Or maybe I know what I'm doing.


----------



## jefft110 (Jul 7, 2010)

Bulldog1 said:


> Or maybe I know what I'm doing.


Says the man who claims a nicked neutral tripped a non-afci breaker.
:thumbsup:


----------



## Bulldog1 (Oct 21, 2011)

jefft110 said:


> Says the man who claims a nicked neutral tripped a non-afci breaker.
> :thumbsup:





I know a high leg when I see one....Evidently you don't....:thumbsup:
I never claimed anything. :no:


----------



## jefft110 (Jul 7, 2010)

Bulldog1 said:


> I know a high leg when I see one....Evidently you don't....:thumbsup:
> I never claimed anything. :no:


Oh...I know a high leg when I see it too.

You, EVIDENTLY, have never made a mistake...


----------



## Bulldog1 (Oct 21, 2011)

jefft110 said:


> Oh...I know a high leg when I see it too.
> 
> You, EVIDENTLY, have never made a mistake...



I make mistakes. I am far from perfect.I would think all the empty spaces on the b phase would of been a clue to you that you were working on a high leg. Here is a high leg service we did a few months ago. We have many customers with high leg services. The only guys I know who have put 120V equipment on the high leg were handymen or apprentices. Never a real electrician.


----------

