Discussion in 'Electrical Forum discussion & Blog' started by molo, Aug 11, 2007.

1. ### moloMember

Joined:
Sep 23, 2006
Location:
Cold New York
1. There is 25 extra feet of it in the attic. IT supplys power to the water tank. Is this costing us more money in electriciity (\$10, \$50, \$100 per year)?

2. Can I the same single pole switch you use for 12/2 lighting switch to provide a disconnect for the water heater at the heater? IT WILL be 10-2 going into the switch.

3. Does a 240 volt heater have to be tied in to a 30 amp double pole breaker or can you use a 20 amp breaker?

TIA<
MoLo

2. ### CassPlumber

Joined:
Nov 12, 2005
Location:
Ohio
The extra wire in the attic is not causing your heater to consume more energy.

No you can't use a SP switch to kill power to the water heater.

Use a non fused, 2 pole, quick disconnect, if you want something to kill power to the water heater without shutting the breaker. It can be located near the heater.

The wire size determines the amperage of the breaker. 12/2 WG would use a 20A breaker 10/2 WG would take a 30A breaker 120V would use a SP breaker and 240V would use a DP breaker.

The watt draw of the heater, which is based on the wattage of the elements, would determine the wire size needed.

Last edited: Aug 11, 2007

4. ### moloMember

Joined:
Sep 23, 2006
Location:
Cold New York
Can the non-fused, 2-pole, quick disconnect be rated for 12 and 10 gauge wires?

5. ### Bob NHIn the Trades

Joined:
Oct 20, 2005
Location:
New Hampshire
A 4500 Watt water heater requires 4500 Watts /240 Volts = 18.75 Amps.

However, the National Electrical Code requires that continuous loads (A household water heater is defined as a continuous load.) may not exceed 80 percent of the capacity of the circuit. Therefore, you must have a circuit that has a capacity of at least 23.44 Amps.

Standard circuits in common use are 20 Amp and 30 Amp. Therefore, it should have a 30 Amp breaker and #10 wire.

That is not to say that it won't work with #12 wire and a 20 Amp breaker (It is drawing only 18.75 Amps.), but it will be in violation of the code.

It would be very dangerous to use a standard light switch with a 240 Volt circuit because someone might think the circuit is turned off by the switch and get zapped when working on it because the other side of the circuit is hot.

There are unfused 2-pole disconnects used with Air Conditioners that would work with a water heater.

6. ### CassPlumber

Joined:
Nov 12, 2005
Location:
Ohio
I don't remember their amp rating but I believe it is over 30A

7. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Disconnected are not rated in wire size, they are rated in amperage. The lugs will have a conductor size range, but this is not the rating of the disconnect.

Most small disconnected are either 30A or 60A.

Also, yes, a single pole switch can be used to turn off a water heater. It CANNOT however be used as the required service disconnect.

8. ### moloMember

Joined:
Sep 23, 2006
Location:
Cold New York
is this the dconnect?

is this it? this is for my well pump

TIA,
molo

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9. ### Bob NHIn the Trades

Joined:
Oct 20, 2005
Location:
New Hampshire
Yes........... .

10. ### hjModerator & Master PlumberStaff Member

Joined:
Aug 31, 2004
Occupation:
Plumber
Location:
Cave Creek, Arizona
disconnect

Only you can tell, because only you can see where the wires are connected.

11. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Is what it? What is the question?

12. ### moloMember

Joined:
Sep 23, 2006
Location:
Cold New York
THIS DCONNECT IS FOR MY WELL PUMP, i"m wONDERING IF THIS IS THE KIND i nEED FOR MY WATER TANK

tia,
MOLO

13. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
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NY State, USA
Yes?

I don't think you'll find one like that but that one will work. A simple little 60A "pull-out" disconnect would be the easiest.

14. ### CassPlumber

Joined:
Nov 12, 2005
Location:
Ohio
A single pole switch can not be used to turn off a 240v water heater.

If the heater was 120v a quick disconnect should still be used in place of a sp switch, in my NSHO.

15. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Cass, please re-read my post. I think I clearly stated it cannot be used as a disconnect.
For control purposes a SP switch most certainly can shut off a straight 240v load.
Have you ever looked at the way the thermostats inside a water heater work??? They are SP.

16. ### CassPlumber

Joined:
Nov 12, 2005
Location:
Ohio
Were talking about installing a sp switch outside of a W/H to cut 240v service to a W/H.

You tell me how a SP switch shuts off both sides of a 240v circuit.

17. ### jimboPlumber

Joined:
Aug 31, 2004
Location:
San Diego
The point about a "switch" meaning a toggle switch mounted in a single gang box....is that you probably wont find one rated for the amps.

I have seen some old 30 gallon heaters with 3500 watt elements, on 20 amp circuits. You could find a double pole switch rated at 20 amps, but I just wouldn't go there on a WH. Today, most 30's and all larger tanks are on at least 4500 watts, meaning 30 amp required. I don't think you will find a 30 amp rated toggle. This becomes a disconnect.

The picture you posted is a disconnect, rated at 30 amps, cant tell if it is fused or not, but fused disconnect not required for a WH, as long as it is coming from a breaker.

18. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
Cass, I don't know how I can be any clearer. I am talking about TWO different things.

First off, Molo is being quite ambiguous about this whole thing. Is he trying to shut off the water heater like a weekender would? Or does he want a service disconnect to work on the unit?

A switch that cuts one leg of a 240v circuit will shut off that circuit. This is a CONTROL, NOT a disconnect.

A two pole DISCONNECT will cut both legs and is required as a service disconnect. Many times the circuit breaker serves this purpose.

A disconnect is not necessarily a switch, and a switch is not necessarily a disconnect.

YES, there certainly are 30A single and double pole toggle switches that fit in standard device boxes, provided the box has enough room for the wiring.

19. ### Dunbar PlumbingMaster Plumber

Joined:
Apr 18, 2005
Occupation:
Service Plumber, Outdoor Temperature Relief Owner
Location:
Northern Kentucky/Greater Cincinnati Area
If you install a HD water heater which always has 4500 watt upper/lower elements on a 12/2 20 amp breaker, it will blow the breaker every single time.

I always tell the customer that if you are supplying me with a HD electric water heater, better have 30 amp breaker in the panel.

3 weeks ago,

"Yeah home depot said that you all would come out and fix the water heater, they pay you for the call but I just installed it a few days ago and the breaker keeps tripping."

"What size breaker?"

"20"

"Whelp, I'll tell you that you have too small of a wire running to your heater, you have to run 10-2 and 30 amp breaker and we collect from you the charges for our time....you take it up with home depot for reimbursement."

"I've put a few of these in with no problems, just this one."

"If you've been ignoring the fact you need a larger wire and circuit to operate these heaters, expect to have to go back to all of them and upsize the wire unless they catch on fire first. GOOD LUCK!!!"

Joined:
Aug 31, 2004
Location:
San Diego
21. ### Speedy PeteyLicensed Electrical Contractor

Joined:
Jun 16, 2007
Occupation:
Location:
NY State, USA
That switch is a welder starter switch. Very specialty.
A Leviton 3031-2 is a 30A single pole toggle. A 3031-2 is a double pole toggle.