# High Leg Delta



## jwjrw (Jan 14, 2010)

I've seen plenty of high leg delta's but until a few weeks ago had never seen one on a house here. Most here if they are three phase are wye not delta. FYI the high leg should be on "B" phase.


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## hardworkingstiff (Jan 22, 2007)

jwjrw said:


> I've seen plenty of high leg delta's but until a few weeks ago had never seen one on a house here. Most here if they are three phase are wye not delta. FYI the high leg should be on "B" phase.


Is that a house?

When I 1st started, the high-leg was on C phase.


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## jwjrw (Jan 14, 2010)

hardworkingstiff said:


> Is that a house?
> 
> When I 1st started, the high-leg was on C phase.


I am bidding a job on a single family dwelling with a high leg. First time I have seen that. We used to connect to the "C" phase but the NEC now requires us to connect to "B" phase.



(E) Phase Arrangement. The phase arrangement on 3-phase
buses shall be A, B, C from front to back, top to bottom, or left
to right, as viewed from the front of the switchboard or panelboard.
The B phase shall be that phase having the higher
voltage to ground on 3-phase, 4-wire, delta-connected systems.
Other busbar arrangements shall be permitted for additions
to existing installations and shall be marked.
Exception: Equipment within the same single section or multisection
switchboard or panelboard as the meter on 3-phase,
4-wire, delta-connected systems shall be permitted to have the
same phase configuration as the metering equipment


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## hardworkingstiff (Jan 22, 2007)

jwjrw said:


> I am bidding a job on a single family dwelling with a high leg. First time I have seen that.


What is the high-leg serving? Is this a mansion that has 3-phase HVAC or pool heaters or..........


> We used to connect to the "C" phase but the NEC now requires us to connect to "B" phase.
> 
> 
> 
> ...


 I'm aware of that, but thanks for posting it.


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## Demac (Apr 28, 2010)

Here's a bit more information. 

No, this wasn't a house. It was an old fire station, and a police station before that. It is now a small town museum. The high leg was there because this panel also powered the pumps that filled an old water tower behind the building. The water tower is no longer used, the pumphouse at the base still has pumps in it but they are long abandoned, and there is no more need for 3 phase power to this building. 

I believe we are going to replace the existing panel with a single phase panel, but the guy I'm working with wasn't sure. 

And yea, in my reading about high leg delta's, I had remembered reading that 'B' phase was supposed to be the high leg. When I mentioned that to my journeyman, he said older installs used the 'C' phase as high.

And since he made me 'fix' it, I double checked that 'C' was the high probably...oh...about 6 times before I turned anything back on. :thumbsup:


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## jwjrw (Jan 14, 2010)

hardworkingstiff said:


> What is the high-leg serving? Is this a mansion that has 3-phase HVAC or pool heaters or.......... I'm aware of that, but thanks for posting it.



The owner built the house in 91 and requested 3 phase power because he has 3 phase woodworking equipment. The POCO dropped him a high leg. Why they didn't make a wye IDK. House is only 4k sq ft. We have some older houses here with 3 phase but all are wye. I am bidding upgrading the high leg to a 400A.


I was posting the change for the OP because he mentioned replacing the panel and that the high leg was on C phase.


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## hardworkingstiff (Jan 22, 2007)

jwjrw said:


> The POCO dropped him a high leg. Why they didn't make a wye IDK.


I'm not sure, but I believe it's less expensive to install 2 transformers (Delta) than it is to provide the Wye.


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## Jlarson (Jun 28, 2009)

A lot of the old 50's and 60's houses here had or still have high leg services. Quite a few of the well sites I work at have it too, mainly the ones in agricultural areas.


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## jwjrw (Jan 14, 2010)

hardworkingstiff said:


> I'm not sure, but I believe it's* less expensive *to install 2 transformers (Delta) than it is to provide the Wye.




I'm sure that was why he ended up with a delta but IDK.


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## B4T (Feb 10, 2009)

The high leg can be an electricians best friend if he lost a lighting job to a trunk slammer..

The guy looks in the panel and sees all these empty spaces he can use to power up the lighting and receptacles..

I hope he plugs in some very expensive electronics.. :laughing:


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## RePhase277 (Feb 5, 2008)

B4T said:


> The high leg can be an electricians best friend if he lost a lighting job to a trunk slammer..
> 
> The guy looks in the panel and sees all these empty spaces he can use to power up the lighting and receptacles..
> 
> I hope he plugs in some very expensive electronics.. :laughing:


That was my very first experience with the high leg. A gas station fed with a 120/240 V delta was converted into a small television and home electronics place. The "electrician" placed all of the show window and display receptacles on the high leg:laughing: Poof! Me and my boss went to look at it. Boss opened the panel door, and at first glance recognized it was a high leg. We chuckled all day.


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## tufts46argled (Dec 23, 2007)

Don't know if it's just a Southern thing but Delta systems are something I've ran into for the 30+ years I've been in the business. That said I've seen it cause many an electrician problems. For a tip, any time I'm in an old area with 3 phase I always look at the transformer feed. Anything less than 3 identical transformers says delta!


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## 2001fltri (Apr 28, 2010)

*3 phase delta*

what ever happened to a simple voltage check? I can't see how anyone can tell voltage at a glance. when i worked for humingus elec. out of philly all of our delta high legs were required to be on C phase in the meter pan , but most customers wanted their panels wired high leg B. Put into that situation and often I will continue to trust nothing but my analyzer.:thumbsup:


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## hardworkingstiff (Jan 22, 2007)

2001fltri said:


> I can't see how anyone can tell voltage at a glance.


I think I've only ever seen 1 Delta service from and U/G and they (POCO) had 2 pad single-phase pad mount transformers to supply this. Most of the Delta services I've seen are overhead services, and like stated earlier, you look at the pole and if you see 2 transformers, you can almost be sure you have a Delta, especially if one is larger than the other.


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