Tankless electric Water heater

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Sierrasparky

Sierrasparky

Senior Member
Location
USA
Occupation
Electrician ,contractor
Anyone care to elaborate as to how a Tanless water heater in a single fam res that has only a 125 amp service , electric heat, electric cooking , does not trip the main. The unit is a 24kw tankless.
 
I would assume if you looked at the trip curve on the breaker and the cycle time on the heater it would make some sense.
 
With 25 amps to play with, not really far fetched to work, the loads are probably cycling enough that at any one time the total load runs around 130-140 amps for short periods of time, then too, it maybe a Federal Pacific breaker too!:lol:
 
Sierrasparky said:
Anyone care to elaborate as to how a Tanless water heater in a single fam res that has only a 125 amp service , electric heat, electric cooking , does not trip the main. The unit is a 24kw tankless.
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Based on testing criteria from NEMA and UL, I would expect both breakers and fuses to be able to carry 125%-135% of nominal rating for at least 2hours. There are several things to consider, not the least of which is ambient temperature.
 
Sierrasparky said:
Anyone care to elaborate as to how a Tanless water heater in a single fam res that has only a 125 amp service , electric heat, electric cooking , does not trip the main. The unit is a 24kw tankless.
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Are ALL of the branch circuits hooked up to the heater? The electric ones I have installed need 3-4 separate branch circuit's.
 
ceb58 said:
Are ALL of the branch circuits hooked up to the heater? The electric ones I have installed need 3-4 separate branch circuit's.
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yup!

I wonder what happens during the holidays and a turkey in the oven , the heat going and someone takes a shower.
 
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