Most economical 1200 amp service

paulengr

Senior Member
Doesn’t it make more sense assuming this is 208/120 or240/120 to run some larger equipment like HVAC at 480 then run to smaller transformers and ILines in each building? Then the 1000 A service is only like 200 A or less. It could all be fed from a 600 V ILine. Each individual building will only need maybe a small roughly 75 kva dry transformer.
 

infinity

Moderator
Staff member
Location
New Jersey
Occupation
Journeyman Electrician
Doesn’t it make more sense assuming this is 208/120 or240/120 to run some larger equipment like HVAC at 480 then run to smaller transformers and ILines in each building? Then the 1000 A service is only like 200 A or less. It could all be fed from a 600 V ILine. Each individual building will only need maybe a small roughly 75 kva dry transformer.
I'm thinking that given the small feeder sizes that it would be more expensive to have a transformer for each of the panel locations.
 

kwired

Electron manager
Location
NE Nebraska
I'm thinking that given the small feeder sizes that it would be more expensive to have a transformer for each of the panel locations.
Might depend on what the loads are to some extent as well. Lots of motor or HVAC loads, maybe still best to go with 480/277, can probably always go 277 on lighting in application like OP is describing, in fact his lighting probably is mostly able to be used on 120-277 anyway.

This may leave you with limited capacity needed for transformers needed to supply general 120, 120/240 receptacles or smaller fixed appliances. Might only need a 5 or 10 KVA single phase transformer for some these loads in each section of the complex.

And if OP was sizing things for 208/120 volts originally, those 200 amp feeders now maybe only need to be 100 amp feeders. Maybe even less if originally was single phase feeders.
 

too many amp

Member
Location
Alabama, USA
Occupation
Agriculture
Thanks for all the input guys. It has been helpful!

I would like to clarify, that the service recommended by the power company is a 120/208/240v 3 phase high-leg delta configuration.

The bulk of the loads are lighting and HVAC. The lighting is rated for 120-277v single phase (switch mode powered LEDs), and the HVAC is rated for 208-240v single phase (inverter powered compressors).

The big question for me now: Will my equipment designed for 240v single phase power operate correctly on this 240v 3 phase system? The voltages will all be in spec, but the guy from the power company did mention that the phase angle between L1 and L2 supplied to the devices being at 120 degrees instead of 180 degrees like they were designed for could potentially cause issues, but he did not know for sure. I have read many topics on the issue and it seems most people say it will work fine, but some say it will cause problems. The manufacturers (or their support at least) seem to have no idea what I am talking about when I say 240v 3 phase high-leg delta..

Sure theoretically I could just run everything from 208v, but I would rather not as it seems less efficient, and also I already have TONS of 120/240 double pole breakers (208v to ground requires a specially rated breaker I think), as well as regular 120/240 panels. If possible I would prefer to ignore the 208v entirely and only go with 120/240. Barely any loads at all will be 120v, such as some small fans and backup lighting.



So nothing would prevent OP's setup from having six sets of underground service conductors feeding six 200 amp service disconnects, or one main underground feed, splice box or gutter and then six service disconnecting means using 2020 NEC.
Yes, that is what I originally intended to get installed.
The guy that said the service would require a single disconnect is the boss of the engineers for my local area, so if he is incorrect about that I don't know what to do about that :oops:


How big is the agricultural warehouse? What are the loads? Is this a large grow room?
The dimensions of the warehouse are 43x60. Yes, it is a large grow room. I listed the types of load above in this post.


Might depend on what the loads are to some extent as well. Lots of motor or HVAC loads, maybe still best to go with 480/277, can probably always go 277 on lighting in application like OP is describing, in fact his lighting probably is mostly able to be used on 120-277 anyway.
My lighting does support 277v, but we are going with smaller AC units because the building is segregated into sealed rooms to prevent cross contamination.

Thanks for the suggestions!!
 
Last edited:

oldsparky52

Senior Member
Did you consider a 480/277 3-phase service? A small transformer for any 120V loads, but the lighting and HVAC could all be ordered to work on the 480/277 service. Smaller panel, less % VD to deal with.
 
Thanks for all the input guys. It has been helpful!

I would like to clarify, that the service recommended by the power company is a 120/208/240v 3 phase high-leg delta configuration.

The bulk of the loads are lighting and HVAC. The lighting is rated for 120-277v single phase (switch mode powered LEDs), and the HVAC is rated for 208-240v single phase (inverter powered compressors).

The big question for me now: Will my equipment designed for 240v single phase power operate correctly on this 240v 3 phase system? The voltages will all be in spec, but the guy from the power company did mention that the phase angle between L1 and L2 supplied to the devices being at 120 degrees instead of 180 degrees like they were designed for could potentially cause issues, but he did not know for sure. I have read many topics on the issue and it seems most people say it will work fine, but some say it will cause problems. The manufacturers (or their support at least) seem to have no idea what I am talking about when I say 240v 3 phase high-leg delta..

Sure theoretically I could just run everything from 208v, but I would rather not as it seems less efficient, and also I already have TONS of 120/240 double pole breakers (208v to ground requires a specially rated breaker I think), as well as regular 120/240 panels. If possible I would prefer to ignore the 208v entirely and only go with 120/240. Barely any loads at all will be 120v, such as some small fans and backup lighting.





Yes, that is what I originally intended to get installed.
The guy that said the service would require a single disconnect is the boss of the engineers for my local area, so if he is incorrect about that I don't know what to do about that :oops:




The dimensions of the warehouse are 43x60. Yes, it is a large grow room. I listed the types of load above in this post.




My lighting does support 277v, but we are going with smaller AC units because the building is segregated into sealed rooms to prevent cross contamination.

Thanks for the suggestions!!
Your equipment will run fine on the two 240 legs of 120/240 three phase. You will however need fully rated breakers for breakers that connect to the high leg. Some manufacturs make such a breaker, other do not and will tell you to use a three pole breaker as they are aways fully rated.

This isnt that big at 43x60, but I would think hard about avoided the 240V trap with this and putting on your big boy pants and going with 277/480. The grow I did I talked tham into going 480 and it is the gift that keeps on giving. Just found out they are adding another room and its such a joy running a circuit for a 20 ton AC at 480 vs 240. I understand these places always seem to want to use min splits, but I dont think that ever pays off either. This place is nixing all their splits as they just arent doing the job and keep failing.
 
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