1000 amp 120/240 single phase service

[KushElectric]

I am trying to help restore a old hotel in my hometown. The power company only has 120/240 single phase to that area so I will be using that for a 1000 amp service. From a CT cabinet to a 1000 amp fusible disconnect. From there we will have a trough to tap into fused feeders to feed several 200 amp main breaker panels above trough. My question is can I use a set parallel of 350 mcm conductors for this or will I need to go up to 500 mcm. Thanks for the help it’s been years since I needed to size wire for a service this big.

 

[infinity]

Are the 350's or 500's on the load side of the 1000 amp OCPD? Are these the conductors that you want to tap?

 

[KushElectric]

Yes sorry that is a important detail. This is on load side and will be the ones being tapped to feed a few 200a main breaker panels, and room for an additional one down the road.

 

[Strathead]

Yes sorry that is a important detail. This is on load side and will be the ones being tapped to feed a few 200a main breaker panels, and room for an additional one down the road.

You can tap either, or. I would actually use 4-250 copper at 1020 ampacity or 4-350 aluminum at 1000 ampacity, if I were you. You just need to buy polaris lugs with the correct size and number of holes to feed all the panels and al the feeders for each phase and the neutrals.

 

[infinity]

I agree with Strat you'll need conductors rated for at lest 1000 amps and then a method to connect to them. Given the current supply chain issues you might start with the Polaris taps and then size the wire and number of sets from there.

 

[KushElectric]

yeah it’s the Polaris taps I’m worried about finding. Good idea to see what I can find then work sizing from there.

 

[jaggedben]

You could bring all your separate 200A taps right into the disconnect, if that makes it eaiser. That is if you can get lugs for the disco for the number of taps you need, distances are all less than 10ft, etc. Devil in the details but there's no rule against it.

 

[tom baker]

I have used Ilsco parallel taps and liked them. Parallel wires lay in the lugs, then ss lugs go or taps. They look nice when done.
Don’t skimp on the wireway size.
I would look at a premade trough, the Hoffman NEMA 1 wireways have a lot of fussy screws to assemble them

 

[electrofelon]

One idea might be to skip the 1000 amp disconnect and come out of the CT cabinet right into the panels using 230.40 exception #2. Seems like that would save a lot of equipment.

 

[kwired]

One idea might be to skip the 1000 amp disconnect and come out of the CT cabinet right into the panels using 230.40 exception #2. Seems like that would save a lot of equipment.

That's what I would usually do myself. 1000 amp disconnect is just wasted $$$ most cases, you still have same four 200 amp main breaker panels either way.

 

[electrofelon]

That's what I would usually do myself. 1000 amp disconnect is just wasted $$$ most cases, you still have same four 200 amp main breaker panels either way.

And it depends on the CT mounting base, but you can probably get an arrangement with enough lugs, either from the factory or by adding them in the field so you don't need to buy any additional connectors.

 

[KushElectric]

Yeah I though of that the electric co-op here is the one wanting it but maybe I can talk them out of it.

 

[kwired]

And it depends on the CT mounting base, but you can probably get an arrangement with enough lugs, either from the factory or by adding them in the field so you don't need to buy any additional connectors.

Around here CT cabinets are just empty cabinets and they put in whatever is needed for the application. Connections often are not mounted blocks but "floating" terminal bars with slip on insulating covers. Same thing they use for open pole top connections in some instances.

 

[electrofelon]

Just be careful about your available fault current, could be up there for a setup like this, especially considering the line to neutral fall current for single phase is likely higher and you should figure that at 1.5 times the line to line. If you are using load centers, the main breakers are probably 22 to 25 kaic. That is one potential advantage of the thousand amp fused disconnect is you could likely get a series rating between that and the 200 and mains...... But then you would need a triple series rating to get the branches covered, and that can be problematic because some manufacturers don't have many triple ratings.
Regular 10K branches will series rate with a 200 amp main all the way up to 100K, so you may need to get equipment with higher than 22k 200 amp breakers.

 

[electrofelon]

Around here CT cabinets are just empty cabinets and they put in whatever is needed for the application. Connections often are not mounted blocks but "floating" terminal bars with slip on insulating covers. Same thing they use for open pole top connections in some instances.

Yeah certainly going to depend on the utility. Where I have done them, both on the east coast and the West coast, they always spec a mounting base for bar type CTS

 

[KushElectric]

Just be careful about your available fault current, could be up there for a setup like this, especially considering the line to neutral fall current for single phase is likely higher and you should figure that at 1.5 times the line to line. If you are using load centers, the main breakers are probably 22 to 25 kaic. That is one potential advantage of the thousand amp fused disconnect is you could likely get a series rating between that and the 200 and mains...... But then you would need a triple series rating to get the branches covered, and that can be problematic because some manufacturers don't have many triple ratings.
Regular 10K branches will series rate with a 200 amp main all the way up to 100K, so you may need to get equipment with higher than 22k 200 amp breakers.

Ok haven’t thought about that!!!! I think I follow what you are saying. I’ll look into that as well.

 

[KushElectric]

So power company now says 1000amp single phase is to hard to get a transformer for. Has anyone had any work with 120/240 3 phase? I am from the industrial world of 120/208 and and 480, I have heard stories of issues with the high leg. Has anyone had dealings with this voltage? Any ideas for a 1000 amp service?

 

[augie47]

For your application 208/120 would be far better. A lot more diversity and a lot less headache than a high-leg system.
(We have had occasion where POCO could not provide single phase in high amps so we got multiple 600 amp services..actually worked better,,more service locations, shorter feeders, less fault current.. food for thought... a 600 at each end ??)

 

[tom baker]

120/208 is preferable over 120/240 wild leg, as the 120/240 required full rated breakers $$$, but the 120/240 can use the common 120 volt breaker
If you are not reusing any line to line gear, then the 120/208 is fine. If you have a 240 motor it won’t be happy on 208.
I had a building with 800 amp wild leg service,it was 700, 700 amps and 300 on the wild leg.

 

[tom baker]

And with the wild leg you can’t use it for lighting and receptacles, if some one does that will let the smoke out