Water heater mistake

[2CRUZ]

Hey guys I need some advice. When I built my garage I was running Romex 12/2 with ground for my lights and when I ran the wire for my hot water heater I just ran romex for it also. I wasn't thinking. Now I am ready to wire it up and I see a black and a red wire comming out of the top of the heater with a ground screw so I figure that it is 240 volt? Looking in the book I see it says use 10 guage wire. I guess you know what my question is. Will the 12/2 be big enough because I don't know how in the hell I could run a bigger wire back up through that wall and down to the panel. Tell me what you think.

 

[mygarageone]

I have seen 12/2 used before but very short run. If that water heater is for your shop only and your not in need of real fast recovery , you can install new 120volt elements and your wiring problem goes away.
I did that for my home w htr and used it that way for a few yrs,

But if you really need the 240 , you could run some conduit to the panel and go that route.

 

[G_P]

How big is the heater? Whats the amperage? I dont think 12ga for a water heater is going to work.

 

[ishiboo]

I have seen 12/2 used before but very short run. If that water heater is for your shop only and your not in need of real fast recovery , you can install new 120volt elements and your wiring problem goes away.
I did that for my home w htr and used it that way for a few yrs,

But if you really need the 240 , you could run some conduit to the panel and go that route.

Not sure why you'd go with a lower voltage water heater... you want the highest voltage you can so you can get the most power over there.

A typical 4500W unit would need #10 wiring. You could remove the element(s) and replace it/them with smaller elements, i.e. two 1500W, one 1500 and one 1650, etc. to get the maximum power with what you ran.

It all depends on the heater you need - recovery, how much water you'll use, etc.

 

[abnorm]

You can find a 20 amp 240 volt water heater......

Mine is a 30 gal with a single heating element and was purchased from a box store......no problems in 12 years of operation (serving 2 adults in an old house.......)

 

[Mustang51js]

If you want to keep same unit you have you will need a new wire ran. Use it for something else and run pipe over for a new outlet. But they do make small water heaters that use 20 amp 240v.

 

[jhelrey]

Bigger wire!

 

[Stuart in MN]

Tell us what the specs are for the water heater. There's no way to provide an answer without that information.

 

[Falcon67]

If this is a standard house 50 gal unit, I'll say you are going to have to re-pull 10 gauge.

 

[Zeke]

Well, if it's a 'hot' water heater, it doesn't have much work to do.

Is this water heater just for the garage? If so, I think you could downsize and be just fine. If the one you currently have is going to draw more than 16 amps continuously, that won't hunt. OK, so you say it won't ever run continuously by the definition of 180 minutes or longer to heat up the water. But, it could if there was a high demand.

80% of the maximum draw is the rule. In another example think of an air compressor. They never take more than a couple of minutes to fill. That is until you ask it to do more than it was designed for like sandblasting or painting a car. I hate to admit it but I've had compressors run for a long time. Maybe not more than 180 minutes, but I'm not going to push that rule.

 

[pattenp]

The OP said the instruction book says to use #10. So what else needs to be known?

 

[southalabama]

Use the 12/2 to pull 10...

 

[mygarageone]

Not sure why you'd go with a lower voltage water heater... you want the highest voltage you can so you can get the most power over there.

A typical 4500W unit would need #10 wiring. You could remove the element(s) and replace it/them with smaller elements, i.e. two 1500W, one 1500 and one 1650, etc. to get the maximum power with what you ran.

It all depends on the heater you need - recovery, how much water you'll use, etc.

Read my response again , what I suggested was because he doesn't have the #10 wire , so this would get him hot water. He would then be able to at least have hot water. You can still get 4500 watt / 120 volt elements and they will work just fine with 12/2

 

[mygarageone]

Use the 12/2 to pull 10...

Great idea except , it's most likely stapled some where in the wall.

 

[2CRUZ]

I guess there is no way around it. I guess I'll have to figure out a way to run a bigger wire. I was kinda hopeing yuou guys would say the 12/2 would be OK.
Thanks Guys

 

[mygarageone]

I guess there is no way around it. I guess I'll have to figure out a way to run a bigger wire. I was kinda hopeing yuou guys would say the 12/2 would be OK.
Thanks Guys

Yes there is , convert the elements to 120 volt and your good to go.

 

[MixManSC]

Unfortunately no, it will not be ok as it is. Either new wire needs to be pulled, the water heater needs to be modified to use 120v elements, or the water heater needs to be replaced with one that has much smaller capacity/electrical requirements. It needs its own dedicated double pole breaker and as mentioned, when you run the new wire, mark the white wire as red, black, or blue so it is permanently indicated as a hot wire.

Hopefully, if you are lucky.... the existing wire is not stapled in the wall and does not have any sharp turns and you could use it to pull the new wire. That would be ideal....

 

[joel63]

Yes there is , convert the elements to 120 volt and your good to go.

^^^^ This will work well for you with no problems.

 

[sberry]

Read my response again , what I suggested was because he doesn't have the #10 wire , so this would get him hot water. He would then be able to at least have hot water. You can still get 4500 watt / 120 volt elements and they will work just fine with 12/2

There are no 4500 watt 120V elements and lowering the voltage doubles the problem. Short run, long run, doesnt matter, the instructions call for 10 wire. As someone said, they do make a size smaller unit, usually used as replacement where hi recharge isn't needed and existing wire may be too small.

 

[nehog]

Use the 12/2 to pull 10...

Just a guess, but the staples might, just might, prove to be a problem!

^^^^ This will work well for you with no problems.

No it won't. Half the voltage requires twice the current for the same power. Twice the current requires heavier wire, not lighter.

Only two viable choices:

1. Find low wattage (say 3500 watt) elements. They exist. This will require two additional things: you must properly mark the heater to indicated that only 3500 watt elements can be used (and make sure your breaker is 20 amps maximum) and you will have to reduce your expectations of how much hot water you'll be getting!

2. Pull 10 AWG wires, which has been discussed above.

 

[Aceman]

Only two viable choices:

1. Find low wattage (say 3500 watt) elements. They exist. This will require two additional things: you must properly mark the heater to indicated that only 3500 watt elements can be used (and make sure your breaker is 20 amps maximum) and you will have to reduce your expectations of how much hot water you'll be getting!

2. Pull 10 AWG wires, which has been discussed above.

I agree with Nehog. These are your only options.

 

[teamextreme]

Read my response again , what I suggested was because he doesn't have the #10 wire , so this would get him hot water. He would then be able to at least have hot water. You can still get 4500 watt / 120 volt elements and they will work just fine with 12/2

You keep harping on lowering the voltage, but you apparently don't understand the relationship between current and voltage. The problem with using #12 is the current is too high for it. Replacing the element with a 120v unit does not help at all (assuming the wattage remains the same), in fact it makes the problem twice as bad because you have increased the current by 2x. The only way to reduce the current is to replace the element with a lower wattage unit and keep the voltage at 240v, as the current will be lower for a given wattage.
1200w heater @ 120v = 10amps
1200w heater @ 240v = 5amps
Unless you can retrofit with a lower wattage 240v element (to get you below 20amps), which you then run the risk of having a heater that doesn't keep up well enough, the proper solution is to run #10.

BTW, a 4500w heater on 120v will draw 37.5 amps! Hardly suitable for a 20amp circuit.

 

[Tbirdtc]

All the people who said use a 110 element duh
A 110 water heater uses 1 220 uses 2 same elements
Does no one understand electricity running at 110 would double the load on the wire 220 more volts requires less amps

How many feet are u running
Consider drop wattage elements
The truth is you are probably fine electrical codes double or triple what u could get away with but if it's a long run I'd say no under 50 ft I'd run it n check temp on wire for a while

This double the volts u half the amps thing is also y u can convert a 6 volt car to 12 and use same wires
If it was reversed u would double the wires

 

[2CRUZ]

It a real short run. The water heater is right next to the panel but I ran the wire up throung the ceiling and down to the top of the panel. Wir is about
10 ft. long.

 

[hidollartoys]

It a real short run. The water heater is right next to the panel but I ran the wire up throung the ceiling and down to the top of the panel. Wir is about
10 ft. long.

Really????? Just run new wire.

 

[kossuth]

It is code in most areas to pull 10/2 for water heaters and 10/3 for electric driers etc amperage of the unit be damned, just size the breaker accordingly. Anyways, you need 10/2 wire. Could the 12/2 work? Sure, and it could be fine for 30-40 years that way, but I caution this. What if your garage catches fire because of the heater and the inspector spots 12/2 in an area where 10/2 normally is? Don't give anybody any reason to Monday-morning quarterback your decisions. Do it once an do it right.

 

[joel63]

Just a guess, but the staples might, just might, prove to be a problem!



No it won't. Half the voltage requires twice the current for the same power. Twice the current requires heavier wire, not lighter.

Only two viable choices:

1. Find low wattage (say 3500 watt) elements. They exist. This will require two additional things: you must properly mark the heater to indicated that only 3500 watt elements can be used (and make sure your breaker is 20 amps maximum) and you will have to reduce your expectations of how much hot water you'll be getting!

2. Pull 10 AWG wires, which has been discussed above.

Yes, I agree with this. Recovery time will be longer.

Sorry for my mistake; I was thinking of lower wattage elements and got fangled up in my thinking.

If It were my situation, I would pull #10.

Thanks for the correction.

 

[gball]

if it's that close, why not just run the new #10 wire in some conduit to the the heater? Use the water tight stuff... it looks cool in (my opinion). Is the panel dry walled in? if so how about coming out of the panel into a recessed box next to panel with a cover that the conduit end can attach to, then to heater...?

 

[Tim F150]

#12 wire is rated for 20 amps. #10 wire is rated for 30 Amps. The 2 heating elements would need to be replaced with a smaller wattage heating element. Never use a bigger amperage rated fuse for a wire size it will cause a fire.

 

[RVDan]

Just bust open the drywall and run the new wire if it's only ten feet.

 

[southalabama]

Try pulling new wire. As others have said staples may present a problem but my experience is that in enclosed walls seldom encounter staples. I'm in the rural south where inspectors aren't by the book NEC followers.

If encounter staples open the wall.

 

[2CRUZ]

I know, I know, It's just that the walls are all finished and painted. I'm going to get up in the attic and see if I can pull that wire up. If so I'll try to tape the 10ga. to it and mabey I can pull it up too.
Thanks guys

 

[ishiboo]

Read my response again , what I suggested was because he doesn't have the #10 wire , so this would get him hot water. He would then be able to at least have hot water. You can still get 4500 watt / 120 volt elements and they will work just fine with 12/2

No, you're quite wrong. The higher the voltage, the lower the amperage at the same wattage.

4500w / 240v = 18.75A. Would work "safely"

4500w / 120v = 37.5A. BAD for #12.

Hence the reason high-power appliances are 240v - you can use a smaller wire.

 

[mygarageone]

No, you're quite wrong. The higher the voltage, the lower the amperage at the same wattage.

4500w / 240v = 18.75A. Would work "safely"

4500w / 120v = 37.5A. BAD for #12.

Hence the reason high-power appliances are 240v - you can use a smaller wire.

Ok , that's probably why I'm not an electrition

 

[1grnlwn]

All the people who said use a 110 element duh
A 110 water heater uses 1 220 uses 2 same elements
Does no one understand electricity running at 110 would double the load on the wire 220 more volts requires less amps

How many feet are u running
Consider drop wattage elements
The truth is you are probably fine electrical codes double or triple what u could get away with but if it's a long run I'd say no under 50 ft I'd run it n check temp on wire for a while

This double the volts u half the amps thing is also y u can convert a 6 volt car to 12 and use same wires
If it was reversed u would double the wires

Not a code monkey but the above advise could get you killed. 20A. on #12 wire max period. No exceptions.

No way in hell you are going to pull a #10 romex thru the wall with that 12-2!

If you can't figure how to run a 10-2 wire, HIRE IT DONE!. Do the job right now and you can forget about it for the rest of time. This is one of those things that you can pay me now or pay me a buttload later.