# Hot Water Heater Wire Gauge



## bphilip (Sep 17, 2010)

I have just bought a cottage and am busy fixing the previous DIY maintenance. The hot water heater is a fairly new 60 gal electric that internally uses 14 gauge wire from the connection point. He has it wired to the the panel (about 50 ft) with only 12/2 wire and a 30 amp breaker. Should I replace this wire with 10/2 ?


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## Speedy Petey (Feb 1, 2004)

bphilip said:


> Should I replace this wire with 10/2 ?


Absolutely. The circuit to this unit should NOT be wired with #12.


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## a7ecorsair (Jun 1, 2010)

Speedy, I'm curious about this because I will be wiring up a heater this fall. 
What if this water heater is 3800 watts and not 4500 watts. Could it be wired with #12 and a 20 amp breaker?
bphilip, what is the wattage of this heater?


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## bobelectric (Mar 3, 2007)

Go by the nameplate specs. I've had to make 40 gal.waters into 120 volt,1500 watt because thats all there was. Just remark the spec tag.


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## Speedy Petey (Feb 1, 2004)

a7ecorsair said:


> What if this water heater is 3800 watts and not 4500 watts. Could it be wired with #12 and a 20 amp breaker?


Yes, but the OP stated a 60 gal heater. I would assume this would be a 4500 watt heater. 
Besides, he states it is on a 30A breaker.


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## hogdogs (Sep 8, 2010)

IIRC, a 30 amp requires 10 AWG or thicker...
20 amp, IIRC, is the largest that allows 12AWG.
This being 220v.
Brent


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## nap (Dec 4, 2007)

hogdogs said:


> I.
> This being 220v.
> Brent


voltage is irrelevant


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## hogdogs (Sep 8, 2010)

Nap, Yep... I wasn't sure if amps and wire size restrictions changed as voltage increased... my code book reading was usually for 220v and below, when over 220v, I went with the boss' calls as I was usually busy in the panel...

Brent


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## nap (Dec 4, 2007)

hogdogs said:


> Nap, Yep... I wasn't sure if amps and wire size restrictions changed as voltage increased... my code book reading was usually for 220v and below, when over 220v, I went with the boss' calls as I was usually busy in the panel...
> 
> Brent


 You need to quit posting about electrical work. The more you post, the more you prove your lack of knowledge in the field. The code separates low voltage into over and under 600 volts, not 220.


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## hogdogs (Sep 8, 2010)

There was no discussion or distinction mentioned regarding high or low voltage. I never made such a reference either...

But I think you are better at voltage drop and ampacity formula than me since you likely calculate these often...

Am I wrong that voltage drop and ampacity are going to require a larger AWG size with 110v than with 220v? or 440? NO I AM NOT!!!

But the fact that my last CURRENT code book was possibly 2003 (if that was a published year) and I don't claim to memorize the stuff...

I done told you it was many years ago... THUS THE "IIRC"...
You sound a lot like an IBEW type guy... 
brent

Just to clarify... it is a "Water Heater" if it was already heated it wouldn't require heating:jester::whistling2:
Brent


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## frenchelectrican (Apr 12, 2006)

Majorty of resdentail electric water heater useally required 30 amp circuit with 6.0mm² { #10 AWG } that will useally cover most of it unless you have oddball size then follow the manufacter details.

But the best answer is check the heater wattage it will stamped on the heater itself that useally give the correct info.

For commercal water heater the bet is out of the window due there are too many diffrent size and setting it need.

Merci.
Marc


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## Stubbie (Jan 7, 2007)

> But I think you are better at voltage drop and ampacity formula than me since you likely calculate these often...


I'll go along with that.....



> Am I wrong that voltage drop and ampacity are going to require a larger AWG size with 110v than with 220v? or 440? NO I AM NOT!!!


BTW its 120 and 240 and 480

Your statement is not true as written 

Over the same distance and the same load requirement the voltage drop is the same if the wire is the same size.

200 feet one way 120 volts using copper 12 awg 20 amp load = 14.9 volts of voltage drop

200 feet one way 240 volts copper 12 awg 20 amp load = 14.9 volts of voltage drop

And I calculated the actual conductor temperature at 30C ambient under the full 20 amps to be more accurate with the voltage drop.

What increases the wire size for 120 volts vs 240 volts is obtaining the same percent of voltage drop between the two voltages.....



> You sound a lot like an IBEW type guy..


As NAPs avatar says "You talking to me?"....


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## Speedy Petey (Feb 1, 2004)

hogdogs said:


> But the fact that my last CURRENT code book was possibly 2003 (if that was a published year) and I don't claim to memorize the stuff...
> 
> I done told you it was many years ago... THUS THE "IIRC"...
> You sound a lot like an IBEW type guy...
> brent


Sorry dude, Nap is absolutely correct here. 

You do not have to memorize the code book, but you have to have a good clue where stuff is and how to find it. _"IIRC"_ does NOT cut it when giving advice based on code. Either get a recent code book and learn how to use it, and not just _"220 and below"_ (which was a pretty scary statement in itself), or stop giving advice to others on electrical work. You are going to get someone hurt.


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## bphilip (Sep 17, 2010)

frenchelectrican said:


> Majorty of resdentail electric water heater useally required 30 amp circuit with 6.0mm² { #10 AWG } that will useally cover most of it unless you have oddball size then follow the manufacter details.
> 
> But the best answer is check the heater wattage it will stamped on the heater itself that useally give the correct info.
> 
> ...


I will check the heater wattage this weekend. I realize I can't leave the 12/2 on the 30 amp breaker, but I am changing the panel as well , since it is an old fuse panel, and I thought I could change the water heater circuit to a 20 amp.


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## rjniles (Feb 5, 2007)

When I bought my house 5 years ago, the home inspection showed the water heater was leaking. I negotiated with the seller to replace it. The WH was a 30 gallon model and I paid to upgrade to a 50 gallon. The seller hired a licensed plumber to do the work. After the closing (dumb me), I noticed that the plumber had reused the existing circuit on the new WH. It was 12-2 on a 20 amp breaker. It was my nickle to upgrade to 10-2, 30 amp.

I guess my point it that there are water heaters that can be used on a 12-2, 20 amp circuit, but you never know what it be changed to in the future. Best to use 10-2, 30 amp.


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## bphilip (Sep 17, 2010)

rjniles said:


> When I bought my house 5 years ago, the home inspection showed the water heater was leaking. I negotiated with the seller to replace it. The WH was a 30 gallon model and I paid to upgrade to a 50 gallon. The seller hired a licensed plumber to do the work. After the closing (dumb me), I noticed that the plumber had reused the existing circuit on the new WH. It was 12-2 on a 20 amp breaker. It was my nickle to upgrade to 10-2, 30 amp.
> 
> I guess my point it that there are water heaters that can be used on a 12-2, 20 amp circuit, but you never know what it be changed to in the future. Best to use 10-2, 30 amp.


That makes a lot of sense to me. I guess the best way to do any job is the right way. It's a lot less hassle in the long run.


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## frenchelectrican (Apr 12, 2006)

I know older electric water heaters used to be run on 20 amp 240 volts circuit as long the wattage is under 2500 watts and per NEC code the water heater and electric heaters are condsering a contiounus load which it mean it can stay on more than 3 hours.

I think the Canada codes are simauir so the best bet is go with 6.0mm² with 30 amp OCPD and be done with it due most of the newer water heaters are using 4500 somecase 5500 watts.

Merci.
Marc


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