# Sizing a 208 high leg



## Hotlegs (Oct 9, 2011)




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## Hotlegs (Oct 9, 2011)

How was this high leg sized when the other 2 line conductors were sized for an 800 amp service. The 2 high legs together don't come close to having an 800 amp capacity so what table in the NEC was used?


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## Hotlegs (Oct 9, 2011)




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## Dennis Alwon (May 9, 2009)

The code does not allow a smaller wire on the high leg-- 200 amps is 200 amps and the wire must be sized accordingly.


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## Hotlegs (Oct 9, 2011)

Dennis Alwon said:


> The code does not allow a smaller wire on the high leg-- 200 amps is 200 amps and the wire must be sized accordingly.


That's what I thought, thank you .


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## Shockdoc (Mar 4, 2010)

That's an old school rule. 

My question is :

If you were doing a 400 amp service w/ one 200 amp single phase panel and one 200 amp three phase panel, can you indeed run a 3/0 cu delta leg ?


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## McClary’s Electrical (Feb 21, 2009)

I disagree Dennis. 


Service conductors shall have sufficient
ampacity to carry the current for the load as calculated​in accordance with Article 220


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## Cletis (Aug 20, 2010)

Does this take into account balancing of the loads in panel or based on worst case scenario unbalanced?


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## jmsmith (Sep 10, 2011)

When I was coming-up, I was always taught that the wild leg only come to play in single-phase use.... You just didn't use it for a line to neutral load. To me if you need three-phase 240V available from the panel, then all your service conductors need to be sized the same. Wouldn't that be right here?
- Jim


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## frenchelectrican (Mar 15, 2007)

mcclary's electrical said:


> I disagree Dennis.
> 
> 
> Service conductors shall have sufficient
> ...


Don't quote me wrong but if my memory serve me right that there were a seperated calculated loads for both single phase et triphase loads.

Merci,
Marc


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## erics37 (May 7, 2009)

I see downsized high legs all the time, I believe Mcclary posted the reference and frenchelectrician backed it up.

For example, we did a school's 800 amp service a few years back, it was 3-phase delta 240 high leg but the only 3-phase loads were a couple of air handlers or something like that. The vast majority of everything else was 120V lighting and receptacles. There were 3 or 4 parallel sets of conductors, (300s or some such) but the high leg wires were just 1/0. Even that was overkill.


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## don_resqcapt19 (Jul 18, 2010)

The service conductors have to be protected per 230.90(A). The only way you can use a reduced size wild leg with a single service disconnect is if the disconnect is fused. 
With a fused switch, it is not uncommon to find 3 sizes of conductors used for a wild leg service. The wild leg is normally the smallest, then the grounded conductor, and the largest would be the other two phase conductors.


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## micromind (Aug 11, 2007)

Shockdoc said:


> That's an old school rule.
> 
> My question is :
> 
> If you were doing a 400 amp service w/ one 200 amp single phase panel and one 200 amp three phase panel, can you indeed run a 3/0 cu delta leg ?


Provided the 3ø panel has overcurrent protection of not more than 200 amps, you'd be legal.

I see these once in a while; usually small markets/convenience stores.


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## frenchelectrican (Mar 15, 2007)

don_resqcapt19 said:


> The service conductors have to be protected per 230.90(A). The only way you can use a reduced size wild leg with a single service disconnect is if the disconnect is fused.
> With a fused switch, it is not uncommon to find 3 sizes of conductors used for a wild leg service. The wild leg is normally the smallest, then the grounded conductor, and the largest would be the other two phase conductors.


That is true Don., however once you go with breaker the bet is throwen out of the window no question asked unless you get a special conferation main breaker which I know it can be order but IMO it don't really justifed the cost to order a oddball one.

Merci,
Marc


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