water heater
- Thread starter domnic
- Start date
- Status
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
simple No. #10 is required with either a 25 amp or 30 amp breaker.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
A water heater such as that is considered continuous-- art. 422.13.
4500 watts/240 volts = 18.75 amps
18.75 * 1.25= 23.5 amps.
OCP cannot exceed 150% 422.11(E)(3)
18.75 * 1.5 = 28 amps-- you may go to the next higher breaker size 422.11(E)(3)
4500 watts/240 volts = 18.75 amps
18.75 * 1.25= 23.5 amps.
OCP cannot exceed 150% 422.11(E)(3)
18.75 * 1.5 = 28 amps-- you may go to the next higher breaker size 422.11(E)(3)
- Location
- Lockport, IL
- Occupation
- Retired Electrical Engineer
The question cannot be answered without knowing the voltage. Dennis used the most probable value of 240. But if the heater were three phase, 480 volts (do they make such things?), the current would be under 7 amps, and a #12 would be acceptable.
mivey
Senior Member
They do, at least 6kW for sure (208, 240, or 480 three phase)
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
4500 watt is a standard size resi. water heater so I used that as the basis. You are correct if it is 3 phase the situation would be different.
mivey
Senior Member
Here are specs for a light-duty commercial Rheem having 3, 4, 4.5, 5, & 6 kW elements:
http://globalimageserver.com/fetchDocument.aspx?id=903e08f3-297c-43a0-a587-e0fae55a8801
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
On the other hand, a 4500w 240v water heater used on 208v would pass 16.25a and use 3380w.
mtfallsmikey
Senior Member
I have Lochinvar 40 gal. htrs. in my buildings, 4500 wt. 277v.
yankj
Senior Member
- Location
- Carrollton, Texas
Do you know how difficult it is to get 277volt heaters?
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
No, but, if you hum a few bars . . .
Sierrasparky
Senior Member
- Location
- USA
- Occupation
- Electrician ,contractor
I have seen many a condo or apartments wired with # 10 Al. serving water heaters. How did that pass?
One-eyed Jack
Senior Member
- Location
- Scotland Neck, NC
Don't know which code cycle that was in. Today #10 Al has a 30 amp rating. This is code compliant for a the 24 amp load of a 4.5 kw water heater. I would not do it. There was a time when the max ocp for a 4.5 kw water heater was 25 amp. Sometime in the 80's.
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