I am in a bind. I have three panels that I want to serve from an underground service. There will be one transformer to serve all three panels. Here is my question... Can I serve three panels with three different conductors underground without going through a main breaker? The panels include a 400 A 208 V 3-phase panel for some rooftop units; a 600 A 220 V Single phase panel for various single phase loads in the building; and a 1000 A 208 3-phase/220 V Single phase panel to serve 12 welding stations. I really do not want to go to one 2000 A panel and then serve three sub-panels. Please let me know if this can be done. Thanks!
Multiple service off one secondary
- Thread starter energywiz
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- Location
- Massachusetts
Re: Multiple service off one secondary
As long as the panels are grouped together you are all set.
230.40 Exception No. 2.
As long as the panels are grouped together you are all set.
230.40 Exception No. 2.
Re: Multiple service off one secondary
I agree with Iwire, but why would you want to use a single phase panel for the single phase loads if you have a 120y/208 service?
BTW, you will either have 120y/208v system or a 120/240v delta, you will not have 208 and 240 v available with one transformer.
What input does your electrician offer?
Roger
I agree with Iwire, but why would you want to use a single phase panel for the single phase loads if you have a 120y/208 service?
BTW, you will either have 120y/208v system or a 120/240v delta, you will not have 208 and 240 v available with one transformer.
What input does your electrician offer?
Roger
Re: Multiple service off one secondary
The existing 120 V single phase panel is an existing switch gear. We added 208/3-phase rooftop units on a new 400 A panel and then had to add a 1,000 A panel for welders that were a mixture of single phase and three phase.
After reading 230.40, I am assuming that each disconnect would need to be fused or be a breaker. Is this the case? Does it need to be switch gear or can each service simply be a subpanel with a main disconnect?
The existing 120 V single phase panel is an existing switch gear. We added 208/3-phase rooftop units on a new 400 A panel and then had to add a 1,000 A panel for welders that were a mixture of single phase and three phase.
After reading 230.40, I am assuming that each disconnect would need to be fused or be a breaker. Is this the case? Does it need to be switch gear or can each service simply be a subpanel with a main disconnect?
- Location
- Massachusetts
Re: Multiple service off one secondary
Each of these will be service disconnects and all grounding and bonding will need to be repeated in each enclosure.
Roger brings up a very good point in that it will be next to imposable to balance the load decently.
It can be any combination of the above as long as there is OCP and no more than six throws of the hand to kill the service.
Each of these will be service disconnects and all grounding and bonding will need to be repeated in each enclosure.
Roger brings up a very good point in that it will be next to imposable to balance the load decently.
Re: Multiple service off one secondary
I do understand about the load balancing. At first I was going to re-wire the single phase panel as a three phase panel so that I could balance the single phase loads evenly on A-B-C. However, the 600 A panel is actuall drawing about 50 to 100 A while the other three phase loads will draw close to their rated loads. The large loads of welders and rooftop units are all three phase loads and should be balanced. I thought that this would not be too bad on balancing.
I do understand about the load balancing. At first I was going to re-wire the single phase panel as a three phase panel so that I could balance the single phase loads evenly on A-B-C. However, the 600 A panel is actuall drawing about 50 to 100 A while the other three phase loads will draw close to their rated loads. The large loads of welders and rooftop units are all three phase loads and should be balanced. I thought that this would not be too bad on balancing.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Re: Multiple service off one secondary
I'm with iwire, forget the single phase panel and go with a three phase instead. You would get a 50% increase in potential power at that panel with having to add only one conductor?
I'm with iwire, forget the single phase panel and go with a three phase instead. You would get a 50% increase in potential power at that panel with having to add only one conductor?
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