On-demand water heater wiring

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Old 07-03-17, 01:37 PM
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On-demand water heater wiring

I am replacing an existing gas fired tank type water heater with an electric on-demand 220v 50Amp unit. It has a 3 wire flex, red + black + yellow/green. Box states that 6AWG wire is required.

The 60 year old house has a service panel with Connecticut Electric style breakers. The neutral and ground busbars are bonded. I have purchased a CE slimline 2 pole 50Amp breaker.

I have already run cable that I bought some time ago and am now having difficulty determining whether the cable is suitable. It is Type NM-B 600V black plastic sheathed AWG6CU 2 Conductor (one black, one white plastic insulation) with AWG10 Ground (paper wrap).

I plan to connect the heater via a receptacle and NEMA 10-50P plug, but I just got those items and find that it states that the Leviton 5206 receptacle is 3 wire non-grounding.

I have read some threads regarding Article 250.140 Exceptions, but I find the answers quite confusing.

Is it safe for me to consider the two AWG6 conductors in my supply cable as "hot" (I will wrap the ends of the white wire with red tape to make that clear) and use the paper wrapped AWG10 as Neutral (and therefore connect it to the "white" neutral blade in the plug/receptacle)?

Likewise, can I connect the "ground" wire in the flex from the water heater to the Neutral blade in the plug?
 
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Old 07-03-17, 02:25 PM
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You need a NEMA 6-50R there is no neutral in that flex, the green/yellow should be the ground conductor, post the model of the water heater so we can see what you have.That receptacle you have is 125/250 volt.
Geo
 

Last edited by Geochurchi; 07-03-17 at 02:29 PM. Reason: add another comment
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Old 07-03-17, 07:27 PM
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Ah, OK. I have just ordered a NEMA 6-50R receptacle and plug. I will return the other model - thank goodness for Amazon!

I have not yet hooked anything up - only put the receptacle box in position and pulled the cable - whew! I was worried that the cable might be wrong - that would have been a real drama.

Thanks for the instant clarification - much appreciated.

I find all of the different NEMA plug styles very confusing - and the rules are full of exceptions that are quite hard to interpret. But, learning as I go along.

Cheers,
 
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Old 07-03-17, 07:37 PM
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It has a 3 wire flex, red + black + yellow/green.
If that is a whip not service cord you may by code not be able to use a plug.

Example of a whip:

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Example of service cord:
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Last edited by ray2047; 07-03-17 at 09:06 PM.
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Old 07-03-17, 08:59 PM
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Just curious..... why are you switching from gas to electric ?
Is the gas.... propane and it has gotten too expensive ?

Natural gas gives you more bang for the buck with water heating.
 
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Old 07-03-17, 11:39 PM
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1. It is not a "whip", just an old service box with a bonded neutral/ground.

2. There is a really, really ugly old Amerigas tank that is resting directly on the ground at a peculiar angle and rusting badly, located directly outside the living room and in the middle of the yard - no idea why it is located where it is - and Amerigas seem to have lost all record of the tank. I view it as a bomb awaiting detonation! This is kind of a holiday home and I do not intend to be here during the coldest months. I only use the gas for heating water - it is definitely cheaper than electricity - but I am not comfortable with a gas water heater, and it takes up a lot of space in my precious garage/workshop.

Gotta go!
 
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Old 07-04-17, 12:26 AM
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But you wrote:
It has a 3 wire flex, red + black + yellow/green.
Aren't you referring to the wires from the on demand water heater? Most on demand water heaters I have seen have a whip not a terminal block for a cord.
 
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Old 07-04-17, 11:07 AM
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The water heater has a plastic sheathed cable with three insulated wires - I assume that is a "service cord" and looks quite suitable to have a NEMA 6-50R plug attached. It is very similar to the cable from service panel to receptacle.
 
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Old 07-04-17, 04:21 PM
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The water heater has a plastic sheathed cable with three insulated wires
On the ones I've seen that is NM-b type cable not service cord. If the wires are solid not stranded it is likely not service cord.
It is very similar to the cable from service panel to receptacle.
Which makes it cable not service cord. Please post a picture: http://www.doityourself.com/forum/li...rt-images.html

Edit: Cheaper than buying a receptacle and plug would be to just hard wire the cables to a non fused 60 amp air conditioner pullout disconnect. (Costs less than $10.) That would meet code and save you money. Plugs are not supposed to be used on cable if that is what is coming from the water heater.

This is just probably me nitpicking and your way may be correct.
 
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Old 07-06-17, 08:05 AM
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It is definitely a service cord - wires are stranded conductor.

I probably would have been better/cheaper with the disconnector box you suggested, but already got the correct plug/receptacle on the way and it will look neater that way. So decision made.

Thanks for all of your help and advice.
 
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Old 07-06-17, 08:39 AM
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Post back if you need any more help.
 
 

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