I have tried to explain to my customer why it is not a good ideal to have a 3 phase high leg panel with 120v and 3 phase circuits in it. They are looking for a better explaination on why they need to have an single phase panel with the 3 phase equipment in another panel. Anybody got a good way to explain this? I was always taught it is not a good ideal to have this because you only get 2/3 of usuable panel spaces for 120v. There only is 2 peices of equipment that need the 3 phase so what I did was set 2 disconects for those and put in a single phase panel for all of the 120 stuff.
3 phase high leg panel
- Thread starter chrsb
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- Location
- Bremerton, Washington
Re: 3 phase high leg panel
I have seen a lot of panels with single and three phase together. But you normally have a two breakers and a space, etc. I like your approach, as someone unknowledgeable may try to use the space for a 120V load.
Just make sure you use a delta rated breaker for the three phase loads/
I have seen a lot of panels with single and three phase together. But you normally have a two breakers and a space, etc. I like your approach, as someone unknowledgeable may try to use the space for a 120V load.
Just make sure you use a delta rated breaker for the three phase loads/
Re: 3 phase high leg panel
It was for a national mobile phone store, the prints called for 32 120V circuits, with an 42 space panel you would only get 28. I tried to explain that they only had 2 3 phase circuits and it was wasting 14 spaces in the panel. Now they are giving my GC a hard time for the extra cost to rework the service.
It was for a national mobile phone store, the prints called for 32 120V circuits, with an 42 space panel you would only get 28. I tried to explain that they only had 2 3 phase circuits and it was wasting 14 spaces in the panel. Now they are giving my GC a hard time for the extra cost to rework the service.
- Location
- Illinois
- Occupation
- retired electrician
Re: 3 phase high leg panel
I installed a panel with a custom bus layout for this type of application a number of years ago. This panel was laid out so that 3 phase breakers would only work in part of the panel and the rest of the panel was laid out so just the buses with 120V to ground were available. This was accomplished by adjusting the layout of how the horizontal breaker connection bars were connected to the main bus bars. I have no idea how much extra that it cost, but it lets you use all of the panel space if you are sure of how many three phase breakers are needed. This was not a field modification, but a factory assembly.
Don
I installed a panel with a custom bus layout for this type of application a number of years ago. This panel was laid out so that 3 phase breakers would only work in part of the panel and the rest of the panel was laid out so just the buses with 120V to ground were available. This was accomplished by adjusting the layout of how the horizontal breaker connection bars were connected to the main bus bars. I have no idea how much extra that it cost, but it lets you use all of the panel space if you are sure of how many three phase breakers are needed. This was not a field modification, but a factory assembly.
Don
Re: 3 phase high leg panel
Why dont you install a trough with 2 3phase disconnect and one panel coming from a main feeder? The only extra cost would be the tough and the disconnects.
Or install a trough with a main feeder and install a small 3 phase panel and the single phase panel?
There is more than one way to skin this cat without much additional cost and meet code.
Why dont you install a trough with 2 3phase disconnect and one panel coming from a main feeder? The only extra cost would be the tough and the disconnects.
Or install a trough with a main feeder and install a small 3 phase panel and the single phase panel?
There is more than one way to skin this cat without much additional cost and meet code.
Re: 3 phase high leg panel
Thats basicly what we did, we set 2 3 phase disconects and one single phase panel. The extra costs was only 400 bucks, 250 for the disconects and 2 hours additional labor. For some reason the people at the mobile phone place didn't understand what a high leg was, I sent a long explaination this weekend so hopfully they will understand now what we had to make the change.
Thats basicly what we did, we set 2 3 phase disconects and one single phase panel. The extra costs was only 400 bucks, 250 for the disconects and 2 hours additional labor. For some reason the people at the mobile phone place didn't understand what a high leg was, I sent a long explaination this weekend so hopfully they will understand now what we had to make the change.
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