400 amp service

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Greg1707

Senior Member
Location
Alexandria, VA
Occupation
Business owner Electrical contractor
I have a customer that is increasing the size of their 1500 sq ft house to 3000 sq ft. Heat, cooking, water heater are all gas. There will be no pool or spas.

The customer has requested a 400 amp service and standby generator.

Will the POCO actually provide 400 amps? With all the upgrades I have done I have never witnessed the POCO change the cable from the pole to the house.
 

Dennis Alwon

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Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
That really depends on the power company. Why does the owner want 400 amps. If he thinks that will stop brown outs etc he is probably wrong. All gas you would not need but 200 amps.

Here iif I upgrade from 200 to 400 amps I let the power company worry about their side. I do however meet with the engineer first
 

stickboy1375

Senior Member
Location
Litchfield, CT
Our power company offers 320 amp services, very typical in the residential world.... I doubt your scenario requires this, but do a load calculation if in doubt, but if a customer wanted me to bill them for a new service, I wouldn't care less if it required it or not.... also, a 400 amp transfer switch is a lot more than a 200 amp transfer switch, just things to keep in mind.
 
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GoldDigger

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Location
Placerville, CA, USA
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Retired PV System Designer
Our ... also, a 400 amp transfer switch is a lot more than a 200 amp transfer switch, just things to keep in mind.
Since he is unlikely to get a generator which can supply 400A, it may make more sense to put a 200A non-service transfer switch on a 200A critical loads sub-panel.


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stickboy1375

Senior Member
Location
Litchfield, CT
Since he is unlikely to get a generator which can supply 400A, it may make more sense to put a 200A non-service transfer switch on a 200A critical loads sub-panel.


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Depends on how many sub panels are already existing, sometimes its just easier to do load shedding. And most people hate having selective loads during a power outage.
 

Dennis Alwon

Moderator
Staff member
Location
Chapel Hill, NC
Occupation
Retired Electrical Contractor
Our power company offers 320 amp services, very typical in the residential world.... I doubt your scenario requires this, but do a load calculation if in doubt, but if a customer wanted me to bill them for a new service, I wouldn't care less if it required it or not.... also, a 400 amp transfer switch is a lot more than a 200 amp transfer switch, just things to keep in mind.


Our 320 meter bases are used for 400 amp services as they are rated 400 amps for non continuous load and 320 for continuous load. A 400 amp load in a home will never see 320 amps continuous
 

stickboy1375

Senior Member
Location
Litchfield, CT
Our 320 meter bases are used for 400 amp services as they are rated 400 amps for non continuous load and 320 for continuous load. A 400 amp load in a home will never see 320 amps continuous

Same here.... Most people couldn't afford a 100 amp continuous load... so the whole point is a joke within itself.
 

ActionDave

Chief Moderator
Staff member
Location
Durango, CO, 10 h 20 min from the winged horses.
Occupation
Licensed Electrician
Our power company offers 320 amp services, very typical in the residential world.... I doubt your scenario requires this, but do a load calculation if in doubt, but if a customer wanted me to bill them for a new service, I wouldn't care less if it required it or not....
I have seen it more than once where customer wants a 400A service so he can tell everybody that he has one. Both the calculated load and the actual load, which is always less, don't come close to 400A.
also, a 400 amp transfer switch is a lot more than a 200 amp transfer switch, just things to keep in mind.
And harder to get in single phase in my little town.
 
I have a customer that is increasing the size of their 1500 sq ft house to 3000 sq ft. Heat, cooking, water heater are all gas. There will be no pool or spas.

The customer has requested a 400 amp service and standby generator.

Will the POCO actually provide 400 amps? With all the upgrades I have done I have never witnessed the POCO change the cable from the pole to the house.


you have a choice to run to 1 400 amp panel or 2 200 amps panels .... with the second option you could use the 200 amp transfer switch on one ...
 
Location
MA
Utility may charge if upgrades are needed. You might want to factor in the possibility of them charging to upgrade a transformer and cable. They will certainly change the service if it's overhead, although I've seen some upgrades slip through the cracks.

I have seen a service running at 380 amps continuous. It damaged a transformer and burned some wire down. Obviously that was partly the utilities fault. It was an empty house under construction. There was never anybody there, but they always had at least 350 amps on it. There was definitely something weird going on there as we had to call the inspector twice to contact the builder to turn the load down. They always knew when their power went out, but there was never anybody there when we showed up. Very strange... Other than that strange house, I've never seen a 400 amp service come anywhere close to 320 continuous.
 

kwired

Electron manager
Location
NE Nebraska
My guess, the POCO will not stop you from putting in the 400 amp service, but they will still only supply it with whatever they feel is necessary for the actual load. Don't be surprised to see it fed from a 15 or 25 kVA transformer max if there is not significant load to justify anything more. I bet with no electric heat, water heat, etc. the peak demand never goes above 100 amps. If it does it is probably because of cooling load, take away the cooling load and it probably will never reach 100.
 

qcroanoke

Sometimes I don't know if I'm the boxer or the bag
Location
Roanoke, VA.
Occupation
Sorta retired........
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