400a service
- Thread starter jap2525
- Start date
- Status
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 400a service
What is the computed load?
What is the computed load?
- Location
- Illinois
- Occupation
- retired electrician
Re: 400a service
Take a look at 230.90(A).
Don
Take a look at 230.90(A).
Don
Re: 400a service
I don't have a computed load per say.This is a 200a existing service that is only used 5 days a year for a festival.The load is not known until everyone shows up and plugs in.It has a meter with a 200a mb 30 cir panel below it.Last year the panel was running at about 130 amps per leg and the main tripped mostly due to the load and august heat combined.I am going to uprage the service and
serve (2) 200a panels with a 320 amp meter can the mains in the panel will be the service disconnects (no 400a main under meter).
I don't have a computed load per say.This is a 200a existing service that is only used 5 days a year for a festival.The load is not known until everyone shows up and plugs in.It has a meter with a 200a mb 30 cir panel below it.Last year the panel was running at about 130 amps per leg and the main tripped mostly due to the load and august heat combined.I am going to uprage the service and
serve (2) 200a panels with a 320 amp meter can the mains in the panel will be the service disconnects (no 400a main under meter).
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 400a service
The only way to answer your question is to do the calculations in article 220, and prove compliance with 230.90, exception three.
The only way to answer your question is to do the calculations in article 220, and prove compliance with 230.90, exception three.
jimwalker
Senior Member
- Location
- TAMPA FLORIDA
Re: 400a service
I would be worried that in years to come more demands will be made and the load could reach 400 for several hours.
I would be worried that in years to come more demands will be made and the load could reach 400 for several hours.
- Location
- Massachusetts
Re: 400a service
I agree with Ryan but it sounds like you can never count on what the load will be.
That being the case I would use 3/0 from the meter to the panels and either parallel 3/0s or 600 kcmil from the service point to the meter.
I agree with Ryan but it sounds like you can never count on what the load will be.
That being the case I would use 3/0 from the meter to the panels and either parallel 3/0s or 600 kcmil from the service point to the meter.
I would say there is more to it than August heat, IMO a 200 amp breaker should carry 130 amps forever even at 100 F.
lady sparks lover
Senior Member
Re: 400a service
I would say only size by the main, not by the meter. Still I think 350Kcmil is too small, it's rated at 310A. For 400A, I would say go with a 500Kcmil.
Lady
I would say only size by the main, not by the meter. Still I think 350Kcmil is too small, it's rated at 310A. For 400A, I would say go with a 500Kcmil.
Lady
- Location
- Massachusetts
Re: 400a service
Lady Sparks, how can we use 500s rated at 380 Amps with a 400 amp OCP if we do not know what the load will be?
FWIW 600s are usually easer to bend than 500s, 600s have finer stranding.
Lady Sparks, how can we use 500s rated at 380 Amps with a 400 amp OCP if we do not know what the load will be?
FWIW 600s are usually easer to bend than 500s, 600s have finer stranding.
Re: 400a service
Keep in mind we do not have a 400 amp main breaker but (2) 200 amp main breakers rated 160 amps continuos each or 320 amps total.using 500mcm rated for 380 amps would be allowed to be protected by a 400 amp main breaker because 380 amps does not correspond to a breaker size and the next size higher is allowed but we do not have a 400amp main breaker which is the basis of my question.
Keep in mind we do not have a 400 amp main breaker but (2) 200 amp main breakers rated 160 amps continuos each or 320 amps total.using 500mcm rated for 380 amps would be allowed to be protected by a 400 amp main breaker because 380 amps does not correspond to a breaker size and the next size higher is allowed but we do not have a 400amp main breaker which is the basis of my question.
- Location
- Massachusetts
Re: 400a service
You can only move up the OCP size to 400 amps, you can not load the conductors above 380 amps.
You have no way of knowing the load here at this service, one day it may be loaded to 400 amps.
The load could be 400 amps up to 3 hours under NEC and UL rules. This would be compliant for the meter base and breakers, it is not compliant for the 500s.
JMO, Bob
You can only move up the OCP size to 400 amps, you can not load the conductors above 380 amps.
You have no way of knowing the load here at this service, one day it may be loaded to 400 amps.
The load could be 400 amps up to 3 hours under NEC and UL rules. This would be compliant for the meter base and breakers, it is not compliant for the 500s.
JMO, Bob
stew
Senior Member
- Location
- federal way,washington
Re: 400a service
Just to ad a bit to this hypothetical situation regarding the load. I wonder if you have say 130 or so amps being drawn fairly stedily when a large motor or 2 start up on top of that? That could sure cause the breaker to tri[p
Just to ad a bit to this hypothetical situation regarding the load. I wonder if you have say 130 or so amps being drawn fairly stedily when a large motor or 2 start up on top of that? That could sure cause the breaker to tri[p
lady sparks lover
Senior Member
Re: 400a service
Lady
But aren't breakers rated for 80%?
Lady
lady sparks lover
Senior Member
Re: 400a service
oh and iwire...
fwiw?
oh and iwire...
fwiw?
ryan_618
Senior Member
- Location
- Salt Lake City, Utah
Re: 400a service
BTW: FWIW=For what its worth.
80% continuos (3 hours or more), 100% non-continuos.Originally posted by lady sparks lover:
But aren't breakers rated for 80%?
Lady
BTW: FWIW=For what its worth.
Re: 400a service
It seems allowed and usual installations are not always code compliant if you get right down to it.On underground installations it is very common to have parallel feeders to a meter base,but,on overhead (pole mounted services),I would have to say a 400a 320a rated metercan with 600mcm up the mast,,,that is not even usually stocked is not common, or parallel 3/0's up a single mast where the derating factor comes into play and not enough holes in the weatherhead,,,,,or (2) 2" risers with 3/0's to to feed a 400a 320a rated metercan.Although the power company in our area allows 500mcm up the mast for this installation I do not believe this to be correct.By rights I feel like, IWIRE, is correct.Since there is no 400 amp main,although unlikely,there is the possibility that a 400amp noncontinous load could be imposed on this service,500mcm which is rated for 380 amps even though only 20 amps lower is not rated for this,parrallel 3/0's up the mast would be even if derated,,,,,,,Thank you all for your inputs.
It seems allowed and usual installations are not always code compliant if you get right down to it.On underground installations it is very common to have parallel feeders to a meter base,but,on overhead (pole mounted services),I would have to say a 400a 320a rated metercan with 600mcm up the mast,,,that is not even usually stocked is not common, or parallel 3/0's up a single mast where the derating factor comes into play and not enough holes in the weatherhead,,,,,or (2) 2" risers with 3/0's to to feed a 400a 320a rated metercan.Although the power company in our area allows 500mcm up the mast for this installation I do not believe this to be correct.By rights I feel like, IWIRE, is correct.Since there is no 400 amp main,although unlikely,there is the possibility that a 400amp noncontinous load could be imposed on this service,500mcm which is rated for 380 amps even though only 20 amps lower is not rated for this,parrallel 3/0's up the mast would be even if derated,,,,,,,Thank you all for your inputs.
- Status