Wiring Water Heater

[oldcpecdr]

Hi All

Replacing a 20 year old electric water heater and plumbed and wired it today. The 220 wiring is 10-2 pre-existing ....two hot leads and uses the ground for the neutral return.

Is there any benefit to rewiring this circuit to the new 4 wire style with a dedicated ground ? It's been working fine since 1972 but I guess I could upgrade it if was warranted....

Just asking..thanks ... Mike B

 

[ForceFed70]

I doubt the ground is acting as the neutral. Does your new HWT need a neutral conductor? Most don't...

 

[oldcpecdr]

Thanks for the quick reply.....so no neutral needed for a water heater ? Well that makes it easy....and I guess safe....

Mike B

 

[ForceFed70]

Thanks for the quick reply.....so no neutral needed for a water heater ? Well that makes it easy....and I guess safe....

Mike B

Check the tank (it will be easy to look at the wiring or read installation manual) or ask your supplier, but in my experience residential HWT's don't use a neutral conductor. So you should be fine.

 

[cowboyjosh]

no need to rewire, don't waste your time or money.

 

[oldcpecdr]

OK it's working fine as it was wired in 1970....BUT ...can someone explain the circuit to me..don't the 2 hots require a neutral to return to the panel ?

Mike B

 

[oleguy]

don't forget the ground to the green screw in wire compartment!!!

 

[OccupantRJ]

OK it's working fine as it was wired in 1970....BUT ...can someone explain the circuit to me..don't the 2 hots require a neutral to return to the panel ?

Mike B

Think of it as the power going down one of the wires to the heater, then down the other wire doing the same, in alternating fashion, rapidly, each acting as each others "return". Therefore, no neutral is needed for strictly 240 operation. Each phase is 120 volts to ground or to a neutral, but 240 relative to each other. Same for a 240 volt motor. Some appliances will have a neutral when 120 is needed for a clock, or certain controls.

 

[sdowney717]

I have a 240 volt welder wired with only 2 hots and neutral
I have a 240 volt table saw wired same.
As long as the device is only 240 no neutral is used.

I have a drier and a stove which when I bought the house was 2 hots and a neutral.
The drier uses 120 for a light bulb as does the stove.
I moved the drier upstairs and rewired the drier to 8/3
I left the stove wire alone. on its aluminum 6/2 wire

 

[nate379]

Welder should be 2 hots and a ground, not neutral.

I guess neutral... ground... ends in the same place, but still.

 

[sdowney717]

(yeah, I meant a ground)
the wire I used is actually just 3 solid conductors, a black, red, white insulated wires. I seem to recall (not totally sure)sending the white back to the neutral bus bar in the box which is bonded to ground, just to be consistent with the colors

 

[mhm993]

sdowney: did you wire the ground (the third prong on 220) to your neutral bar?

 

[sdowney717]

I might have, not sure.
I assume It should go on the ground bar.

 

[sberry]

In a main entrance service panel the ground could go to the neutral bar. That might be why some confuse N and G.

 

[galute]

I'm not an electrician, far from it actually but I have often wondered what is the reason for running two wires, a neutral and a ground, back to the box when they are essentially hooked together in the box? Just trying to understand.

 

[sdowney717]

neutral carries current returning to the breaker box.
ground carries no current unless the live hot circuit somehow touches conductive metal parts of the case of what is plugged into the outlet. Then the ground path takes the current back to the breaker box keeping you from a potential shock

 

[sdowney717]

The reason something like an electric drill has no gound wire is called double insulated.
The plastic parts are not conductive to current, so the ground is a waste of copper resources.
In the very old days, a drill would have a metal case and still was not grounded. If the live wires inside touched the metal outer case, you could get a shock if you were holding the drill and somehow part of your body was grounded, perhaps in contact with water in a bathtub etc... You then become a part of the circuit returning power to ground or neutral.

If you were part of the neutral return circuit, you are still part of the return to ground so that is also a shock hazard.

 

[galute]

Ok, I can understand that but my next question would be, what stops the current that is being carried by the neutral back to the box from back feeding up the ground back to the case and shocking you any way since they are hooked together in the box? That's the part I don't understand.

 

[sdowney717]

Today, you can have a GFCI circuit. This detects an 'imbalance' in current flowing comparing outgoing hot to incoming neutral. If there is a 'leak' where current is not balanced, then the thing will turn off the power. It does thios before your heart can beat, very fast, so you wont die.
In a GFCI circuit, the ground wire is not needed.

 

[sdowney717]

back feeding up the ground back to the case and shocking you

I suppose because current is seeking out the path back to where it came from, the generating station. So it wont want to do anything but that.
Lightning might go anywhere but it is a different type of thing.

 

[galute]

I suppose because current is seeking out the path back to where it came from, the generating station. So it wont want to do anything but that.
Lightning might go anywhere but it is a different type of thing.

DOOAAAHHH!!! The path of least resistance. Now I get it, makes perfect sense. Thank you.