H2-O 30 amp

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1793

1793

Senior Member
Location
Louisville, Kentucky
Occupation
Inspector
I have a customer with a 65 gal electric water heater, upper 4500, lower 4500, total 4500 watt at 240V installed in 2004.

About every 4 ? 6 months it trips the breaker. Currently this heater is on a 20 amp FPE Double Pole with #12. At the panel I get 18.3 amps per leg and at the heater I have 235v line to line.

I am looking at moving this to a 30 amp circuit with #10.

Any other ideas? What am I missing?
 
George Stolz

George Stolz

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Staff member
Location
Windsor, CO NEC: 2017
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Service Manager
What are you missing? Just a blessing, I guess. Go for it. :)

They probably upgraded the water heater without looking at the wiring. The old tank was probably smaller. My 30-gallon originally had a 15A 240V circuit supplying it. When it went out, I got a 40-gallon and had to upgrade to a 30A circuit.

Edit: Talk them into swapping out their old FPE for something less pyrotechnically inclined. :)
 
1793

1793

Senior Member
Location
Louisville, Kentucky
Occupation
Inspector
Those FPE around here are VERY expensive. I bought a 15 amp single pole and I had to take out a small business loan, $41.00 +tax at supply house.
 
1793

1793

Senior Member
Location
Louisville, Kentucky
Occupation
Inspector
I was looking to see if I was thinking correctly, that even though the water heater is pulling 18.3 amps and the breaker is a 20 amp, it should hold. My thought to move to the 30 amp was due to Article 422.13.:eek:
 
J

jeff43222

Senior Member
Location
Minneapolis, Minnesota
1793 said:
I have a customer with a 65 gal electric water heater, upper 4500, lower 4500, total 4500 watt at 240V installed in 2004.

About every 4 – 6 months it trips the breaker. Currently this heater is on a 20 amp FPE Double Pole ...
Click to expand...

All bets are off when FPE is involved. I'd go with George's suggestion for an upgrade to a better panel.

Either way, #10 30A 2-pole is how I'd wire it. I don't know if the load would be continuous, but if it is, Tom's right about the 80% limit.

And you can get single-pole 15A FPEs at Big Orange for $30 + tax. The supply houses I use don't carry FPEs. They probably don't want to be sued. :D
 
J

jeff43222

Senior Member
Location
Minneapolis, Minnesota
georgestolz said:
Originally Posted by jeff43222:
I don't know if the load would be continuous...

Yes, it is.
Click to expand...
Around these parts, water heaters tend to be gas-powered, and they work intermittently. I didn't realize electric-powered ones stayed on for more than three hours.
 
C

coulter

Senior Member
LarryFine

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
jeff43222 said:
Around these parts, water heaters tend to be gas-powered, and they work intermittently. I didn't realize electric-powered ones stayed on for more than three hours.
Click to expand...
They do if you leave the hot water on. Laundry day, for example.
 
don_resqcapt19

don_resqcapt19

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Staff member
Location
Illinois
Occupation
retired electrician
Yesterday, I was right with you, but I recently looked at the trip curve for a SQD QO CB. It doesn't look like it would ever trip at 100%.
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The UL standard for circuit breakers and fuses says that they can run at 135% of rating for an hour without tripping. UL also requires that the breaker or fuse carry the rated current forever when tested in open air by itself. If you have number of breakers next to each other operating close to full load they may trip near the 80% level.
Don
 
H

hillbilly

Senior Member
Speaking of FPE breakers, has anyone seen the "Federal Pioneer" Stab-Lok GFCI breakers? They're for sale on E-Bay.
steve
 
C

coulter

Senior Member
don_resqcapt19 said:
...If you have number of breakers next to each other operating close to full load they may trip near the 80% level....
Click to expand...

Don -
How did you pick out that 80% number?

I went over the SQD QO trip curve and notes, and also reviewed a CH similar style CB trip curve. I couldn't find anything that would give any indication other than "indeterminate" - which would mean that 30% or 99% are equally valid as 80% for a "may trip near" number.

Did you have another source that pins this down a little closer?

carl
 
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