Question about a high leg panel

[fisherelectric]

Remodeling a restaurant with a 600amp 3 phase service w/ high leg. I want to install a 3 phase 200 amp mlo panel with feed through lugs, tap from the feed thru lugs and install a single phase panel beside it for all the numerous 120 v loads, leaving out the hi-leg. Total connected load ~150 amp for both panels. Is there a problem with that install?

 

[Fulthrotl]

Remodeling a restaurant with a 600amp 3 phase service w/ high leg. I want to install a 3 phase 200 amp mlo panel with feed through lugs, tap from the feed thru lugs and install a single phase panel beside it for all the numerous 120 v loads, leaving out the hi-leg. Total connected load ~150 amp for both panels. Is there a problem with that install?

both panels are 200 amp bus, and you are daisy chaining 3/0 copper to tie them?

is the 3 phase panel 3ph. 4 w. so there is a neutral bus to land the second panel neutral on?

 

[augie47]

Will you have a 200 amp OCP ahead of the 200 amp MLO panel ?

 

[fisherelectric]

Sorry to reply so late.
Yes, the 3phase panel is 4 wire w/ a neutral and is fed from a 200 circuit breaker disconnect. I would be using 3/0 cu to feed from 3 phase feed thru panel to single phase panel, leaving out the hi-leg. Both panels are 200 amp rated. Total connected load will be less than 200 amp. I was worried there may be a problem with dropping the hi-leg and only using single phase for my second panel.

Thanks for your questions, and your answers.

 

[augie47]

I see no problem with the plan.

 

[fisherelectric]

Thanks Augie, I guess I was thinking of problems with balancing the load with so many 120 V loads on A and C and a pretty minimal load on the hi-leg B.

 

[Fulthrotl]

Sorry to reply so late.
Yes, the 3phase panel is 4 wire w/ a neutral and is fed from a 200 circuit breaker disconnect. I would be using 3/0 cu to feed from 3 phase feed thru panel to single phase panel, leaving out the hi-leg. Both panels are 200 amp rated. Total connected load will be less than 200 amp. I was worried there may be a problem with dropping the hi-leg and only using single phase for my second panel.

Thanks for your questions, and your answers.

should work fine.... feed a spoonful of it to iwire, and if he doesn't spit it out...... :happyyes:

 

[kwired]

Thanks Augie, I guess I was thinking of problems with balancing the load with so many 120 V loads on A and C and a pretty minimal load on the hi-leg B.

That could be problem in some cases. Your 200 amp three phase supply is (assuming big enough transformer) able to supply about 83 kVA. There is no way you can supply 83 kVA of 120 volt load without some kind of transformation to be able to use the 208 volt leg.

This system is generally used for one or two reasons.

1 there is a lot of single phase load and limited three phase load - in that case POCO may supply it with either open delta or even full delta but a larger transformer on the 120/240 single phase portion to compensate for the higher loading on that part of the bank. POCO is often also supplying other 120/240 single phase services from same transformer bank.

2 there is a lot of three phase load and limited single phase load - in that case POCO will supply it with full delta and all three transformers are same size. This gives you little higher voltage and lower current for the (presumably) motor loads or a little more bang for the buck in a way than using a 208 volt wye system.