Jdb3

[JDB3]

I am having problem with a residential load calculation. Mother & daughter in a 2 story, total electric house, with each one living on different floors, hence 2 kitchens, 2 clothes washers, 2 clothes dryers, etc..
2529 square feet of living 2 8KW furnaces 2 4.8KW heat pumps
2 ranges 2 microwaves 2 dryers 2 clothes washers
2 bath heaters @ 1250 watts 4 small appliance circuits
1 28,000 watt (4 30 amp circuit) tankless water heater
2 1250 watt bath heaters AND 30 amp 120 volt / 50 amp 240 volt
receptacles @ 2 locations for motor homes.

I come up with a 400 amp service, but others are bidding using 320 amp. Is my 400 amp correct, or am I miss figuring? Help would be greatly appreciated! Thanks, Joe.

 

[Dennis Alwon]

I am having problem with a residential load calculation. Mother & daughter in a 2 story, total electric house, with each one living on different floors, hence 2 kitchens, 2 clothes washers, 2 clothes dryers, etc..
2529 square feet of living 2 8KW furnaces 2 4.8KW heat pumps
2 ranges 2 microwaves 2 dryers 2 clothes washers
2 bath heaters @ 1250 watts 4 small appliance circuits
1 28,000 watt (4 30 amp circuit) tankless water heater
2 1250 watt bath heaters AND 30 amp 120 volt / 50 amp 240 volt
receptacles @ 2 locations for motor homes.

I come up with a 400 amp service, but others are bidding using 320 amp. Is my 400 amp correct, or am I miss figuring? Help would be greatly appreciated! Thanks, Joe.

A 400 amp service uses a 320 amp meter base. Here is the problem. A 200 amp meter base is rated 200 amps for non continuous loads but is only rated 160 for continuous loads.

The 320 amp meter bases, for some odd reason, are backwards-- The 320 amps is the continuous rating of the meter but it is good for 400 amps non continuous.

Why they just don't call the meter base a 400 amp base is beyond me. It would simplify things.