240V instantaneous hot water heater wiring. The cord has three wires not four? Need wiring guidance.

[John Galt]

I bought a 6.5kW instantaneous hot water heater for my cabin. Requires 240V 30 amps service. I ran 10 gauge solid copper to the install site (black, red, white and bare copper) through conduit. I bought a junction box plug receptacle for the four wires, expecting the black and red as hot, white as the neutral and the bare copper as the ground. I was expecting to plug the heater in to the junction box with a four prong plug. The cabin is not heated so I need to be able to unplug the heater and remove it so I can store it at home in a heated space in winter.

What has me perplexed is the heater arrived and it comes with a cord that only has three wires (black, red and green) with no white wire or bare wire it also calls for using a ELCB (earth leakage circuit breaker) which I am unfamiliar with, I was planning on installing a GFI breaker in the Squard D box.

The instructions are also confusing since it says the neutral wire is blue or black !?

Any guidance would be greatly appreciated.

 

[wwillson]

Most water heaters are purely resistive loads and do not need a neutral. My electric water heater is does not have a neutral. Only having three wires for a 240v application threw me off, until I asked an electrician why...

 

[Aredeeem]

Let’s see…water, 240 volts. Fabricado en China. I think I would stop at installation step #1.

 

[dnewton3]

It appears to me that the instructions are written improperly, assuming this is a 240v based unit. To only have one "live" wire, and a neutral and a ground would indicate it's a 120v system. You need to check you have the right unit and perhaps they put the wrong instructions in the box.


Presuming it's actually a 240v unit:
Here is how I would do it, based on the actual label on the wire (which seems much more believable) ...

 

[Urshurak776]

The instructions seem to be European color code? Where did you buy this? What model is it?

 

[John Galt]

Dnewton 3,

I think you are right, the instructions are wrong or poorly written or the interpretation from the Chinese is wrong. The unit is 240V. Your reply made me look for the label on the unit and it seems to clarify what the wires are. See attached. And thanks for the which wire goes where feedback, very helpful!

Do you have any advice on the ELCB requirement? Will a GFI breaker at the Square D box provide equal or better shock protection?

 

[John Galt]

The instructions seem to be European color code? Where did you buy this? What model is it?

Amazon.

 

[eljefino]

Step 3 is written for a foreign country where 240V is power (hot), neutral, and ground. US is wired Power Hot +120, power hot -120, and ground.

Step 3 also seems to be an instruction for wiring the breaker, not the unit.

Red and black go to your breaker screws, green goes to ground. Your outlet will have a neutral, which you can ignore. Should be at 3 o'clock in your picture-- directly opposite the L-shaped ground. Edit: What dnewton diagrammed looks good.

Off topic, what are you doing for water disconnects?

 

[Mazomopar]

looks like NEMA L14 30R spec'd plug so I would think a diagram should be available for that.

 

[John Galt]

Step 3 is written for a foreign country where 240V is power (hot), neutral, and ground. US is wired Power Hot +120, power hot -120, and ground.

Step 3 also seems to be an instruction for wiring the breaker, not the unit.

Red and black go to your breaker screws, green goes to ground. Your outlet will have a neutral, which you can ignore. Should be at 3 o'clock in your picture-- directly opposite the L-shaped ground. Edit: What dnewton diagrammed looks good.

Off topic, what are you doing for water disconnects?

Very helpful. So if I remove the plug/junction box from the diagram I end up connecting it like this picture to a 30 amp breaker in my box with the free green wire connected to the bare copper ground wire (or to where the white wire terminates)

 

[John Galt]

looks like NEMA L14 30R spec'd plug so I would think a diagram should be available for that.

Yea that’s part of the confusion. It is UL listed so I expect it conforms to U.S.A. electrical code norms. (?).

The plug terminals are marked G, W and X and Y, the plug instructions say X and Y are for the hot wires. See picture.

Per post # 4 of this thread, the green goes to the terminal marked G and the red and black wires go to terminals X and Y on the plug and I leave the W terminal empty on the male plug.

I will be attaching the white wire to the female receptacle at the appropriate terminal and to the appropriate termination strip in the breaker box.

 

[Hall]

I don't remember specifics, but you often run into a similar situation with clothes dryer hook-ups between 3-wire and 4-wire options. You can still hook things up, you just connect things a certain way. Sorry that is so vague....

 

[mrnkc130]

240v doesnt need a neutral it has two legs of 120 using the opposite leg as a return to ground, if you have something with 120/240 then you need the neutral so one leg of the 240v had a way to get back ground as a 120v circuit. More common now with things like hot tubs etc because they have 120v lights and controls now etc

 

[2005jettatdi]

240v doesnt need a neutral it has two legs of 120 using the opposite leg as a return to ground, if you have something with 120/240 then you need the neutral so one leg of the 240v had a way to get back ground as a 120v circuit. More common now with things like hot tubs etc because they have 120v lights and controls now etc

This! You explained it very well. No one should attempt wiring without at least reading Wiring Simplified. Make that reading and understanding. In this case, since there is no 120v use in the water heater, there is no need for a neutral.

 

[wwillson]

240v doesnt need a neutral it has two legs of 120 using the opposite leg as a return to ground

When there is no neutral, each hot 120v wire is 180° out of phase, hence the 240v potential. There is no ground in the 240v circuit, only a return path to the ends of the secondary winding in the transformer. The neutral is the return path to the center tap, which provides 120v. There is a ground, but it's not in the transformer.

 

[Aredeeem]

Yikes, why is BITOG allowing itself exposure to this kind of possible litigation? Call a licensed electrician. Get the install done. Let us know how it turns out. A first year accident attorney can trace its way back to bad advice if something goes haywire.

 

[Astro14]

Yikes, why is BITOG allowing itself exposure to this kind of possible litigation? Call a licensed electrician. Get the install done. Let us know how it turns out. A first year accident attorney can trace its way back to bad advice if something goes haywire.

Isn’t that true for nearly every single topic on this forum? People give bad advice all the time, whether it’s about oil, tires, suspension work, brakes (installing used brake parts, for example) and safety equipment.

I’ve seen people recommend storing tires in their bathtub, or fixing transmissions on the kitchen table. No regard for fire safety in those posts. Same with storing 50 jugs of oil in your apartment, which, I’m quite sure, exceeds the lease and/or insurance limit.

We’ve all seen advice about just putting tape over an airbag light, for example, or the guy who argued that driving without an airbag for three years was perfectly fine.

What is it about electrical work that would expose the site to litigation, any more than any one of those foolish, ridiculous, ill-advised practices and recommendations?

If we were to moderate content on the basis of common sense, or best safety practices, I suspect that about half the posts on this site would have to disappear.

 

[eljefino]

I will be attaching the white wire to the female receptacle at the appropriate terminal and to the appropriate termination strip in the breaker box.

Cool. This wire will do nothing for your current setup but future-proof it.

Edit, b/c I misunderstood.

 

[Pablo]

Yikes, why is BITOG allowing itself exposure to this kind of possible litigation? Call a licensed electrician. Get the install done. Let us know how it turns out. A first year accident attorney can trace its way back to bad advice if something goes haywire.

I'm a bit curious about this?

How is it that cheaparse accident attorneys are not doing this on just about anything you can groogle or yerboob about? Because there is some REAL sheetpoop advice all ober dee net

 

[Nukeman7]

Dnewton 3,

I think you are right, the instructions are wrong or poorly written or the interpretation from the Chinese is wrong...

Do you have any advice on the ELCB requirement? Will a GFI breaker at the Square D box provide equal or better shock protection?

An Earth Leakage Circuit Breaker (ELCB) is generic/international verbiage for what the USA calls a Ground Fault Circuit Interrupter (GFCI).