400 amp service is only 320 amps ?

Stevenfyeager said:
Our POCOs around here have always said their 400 amp service is really only 320 amps. Is that true only in my area ?
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No, it's everywhere. 320A is for continuous use. There is a true 400A for continuous but for residential, they use 320A meter bases.
You still get 400A, but not for continuous use, which you should never need on a dwelling.
320A x 125% = 400A
 
The 320/400A meter base seems to be the only one that differentiates between continuous and non-continuous ratings. I believe the CL100 and CL200 meters are continuous ratings, so you could see a CL100 on a 125A service and a CL200 on a 225A service. But the power company will tell you their limits for meter class on a given service. A "400A residential" service typically uses a class 320 meter and I would expect you could use it up to a calculated load of 400A non-continuous.

I would expect when someone says they want a "400A service" that is a non-continuous rating because a 400A continuous service would need a 500A main breaker and 500A conductors unless the breaker was 100% rated.
 
Stevenfyeager said:
Our POCOs around here have always said their 400 amp service is really only 320 amps. Is that true only in my area ?
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A lever bypass meter socket for a residential service is rated for 320 amps continuous duty and is the largest single phase meter that our local PoCo will allow without a CT cabinet. I have installed larger residential services(400-600 Amp) but they all required large CT cabinets with the meter base mounted to the CT cabinet.
 
And if you think that a poco xfmr feeding 4 houses will provide even a single 320A continuous (......:mad:

Volunteer engineer at habitat project questioned that the poco had only a 20KVA xfmer (yes twenty) feeding 4 housing units with 200A services each..
POCO said they would upsize if there were ever a problem, all units have electric stoves but gas heat and gas water heaters. No electric cars (yet).
 
junkhound said:
Volunteer engineer at habitat project questioned that the poco had only a 20KVA xfmer (yes twenty) feeding 4 housing units with 200A services each..
POCO said they would upsize if there were ever a problem, all units have electric stoves but gas heat and gas water heaters. No electric cars (yet).
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Exactly.
Way oversizing things there (there's an NEC working group for that).

I regularly do apartment projects where there is 10A to 25A per unit total (e.g. 175 amp fuses, ten units plus laundry).
There's never a problem. Even adding EV charging is fine.
And with the advent of the Charlie Oven, and its eventual clones, there never will be a problem.
 
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