Water heater wired incorrectly

[nizak]

I ran across a 4500W 240V water heater that has been connected to a 120V receptacle. It is drawing 1100 watts .

The cord is 16-3 SJO and I’m told has been operating this way for several years.

The demand on the heater is so low that they never experience a loss of hot water because it has ample time to recover.


I told the owner that it needed to be corrected and he said it’s worked fine and not to do anything with it.

I know that it is wrong to leave it, but is there any chance that it could ever draw enough current to compromise the cord before the breaker tripped?

It’s protected by a 15A breaker.

Thanks

 

[Dennis Alwon]

It draws 1100 watt @ 120v which is 9 amps. I can't see how it can draw more than that.

 

[qcroanoke]

I ran across a 4500W 240V water heater that has been connected to a 120V receptacle. It is drawing 1100 watts .

The cord is 16-3 SJO and I’m told has been operating this way for several years.

The demand on the heater is so low that they never experience a loss of hot water because it has ample time to recover.


I told the owner that it needed to be corrected and he said it’s worked fine and not to do anything with it.

I know that it is wrong to leave it, but is there any chance that it could ever draw enough current to compromise the cord before the breaker tripped?

It’s protected by a 15A breaker.

Thanks

I would disavow any knowledge of ever being in the building.

 

[nizak]

I would disavow any knowledge of ever being in the building.

My work is requiring a permit.
I will let the inspector deal with the homeowner.

 

[hbiss]

I will let the inspector deal with the homeowner.

It's cord and plug connected and operates well within the ampacity of the circuit. I can't see how he would care and you shouldn't either.

-Hal

 

[winnie]

You've pointed out the issue to the homeowner. I think you can cover your liability by notifying them in writing that it is a non-standard installation.

As installed neither the circuit nor the power cord will be overloaded, though as a non-standard installation I'm sure someone could find actual code violations (flexible cord used as permanent wiring perhaps)?

I wouldn't lose sleep leaving the installation as is.

-Jonathan

 

[Barbqranch]

I ran my water heater on 120 volts for a couple of months during a remodel. Always had enough hot water. I considered wiring it that way permanently when I got a generator, but I ended up with a generator large enough to handle it on 240.

It might even make the elements last longer.

 

[electrofelon]

You've pointed out

though as a non-standard installation I'm sure someone could find actual code violations (flexible cord used as permanent wiring perhaps)?

Here is uses permitted:

400.10 Uses Permitted.
(A) Uses. Flexible cords and flexible cables shall be used only
for the following:
(1) Pendants.
(2) Wiring of luminaires.
(3) Connection of portable luminaires, portable and mobile
signs, or appliances.
(4) Elevator cables.
(5) Wiring of cranes and hoists.
(6) Connection of utilization equipment to facilitate
frequent interchange.
(7) Prevention of the transmission of noise or vibration.
(8) Appliances where the fastening means and mechanical
connections are specifically designed to permit ready
removal for maintenance and repair, and the appliance
is intended or identified for flexible cord connection.
(9) Connection of moving parts.
(10) Where specifically permitted elsewhere in this Code.
(11) Between an existing receptacle outlet and an inlet,
where the inlet provides power to an additional single
receptacle outlet. The wiring interconnecting the inlet
to the single receptacle outlet shall be a Chapter 3
wiring method. The inlet, receptacle outlet, and Chap‐
ter 3 wiring method, including the flexible cord and
fittings, shall be a listed assembly specific for this

I think 6 or 8 are the only routes, but may be a stretch. "Intended or identified" might be tough to show. I think one could just argue 6, say you like to change your water heater every month because you are paranoid about it leaking and it's a free country and you're free to do so

 

[Hv&Lv]

Here is uses permitted:



I think 6 or 8 are the only routes, but may be a stretch. "Intended or identified" might be tough to show. I think one could just argue 6, say you like to change your water heater every month because you are paranoid about it leaking and it's a free country and you're free to do so

Mike Holt may argue otherwise..

Code Q&A: Using Flexible Cords to Connect Appliances

Test your NEC knowledge.

www.ecmweb.com

 

[electrofelon]

Mike Holt may argue otherwise..

Code Q&A: Using Flexible Cords to Connect Appliances

Test your NEC knowledge.

www.ecmweb.com

The ambiguity with (6) is the code does not say what is, nor who gets to determine, what frequent interchange is.

 

[kwired]

I have one

The ambiguity with (6) is the code does not say what is, nor who gets to determine, what frequent interchange is.

True, would end up being AHJ judgment call and could be different decision in different situations. Most would likely lean toward not allowed to use the cord unless there is some rather obvious situation of frequent interchange though. I doubt most typical domestic WH installations would be seen that way though.

 

[winnie]

I'd note that there are lots of appliances which are plugged in once, and left plugged in until they are being replaced.

A dishwasher or a clothes washing machine get plugged in using a flexible cord, get connected to plumbing, and stay plugged in until they are being repaired or replaced.

-Jonathan

 

[kwired]

I'd note that there are lots of appliances which are plugged in once, and left plugged in until they are being replaced.

A dishwasher or a clothes washing machine get plugged in using a flexible cord, get connected to plumbing, and stay plugged in until they are being repaired or replaced.

-Jonathan

Those are listed for this kind of installation and some even come with the cord installed from the factory.

Most storage type electric water heaters are not this way.

Smaller capacity instant water heaters can be this way.

Many gas water heaters with combustion blower and controls do come with cord and plug that is factory installed as well.

 

[winnie]

Those are listed for this kind of installation and some even come with the cord installed from the factory.

Most storage type electric water heaters are not this way.

I agree. The installation being discussed is not standard, and raised flags with the OP. It might also raise flags with the inspector.

I'm just saying that I wouldn't lose sleep over this installation.

If it were my job, I might want to get a closer look to make sure that there weren't dangerous errors in the installation, such as improper strain relief for the flexible cord, or incorrect splices from flexible cord to tank wiring, but I don't believe this is an inherently unsafe setup.

-Jonathan

 

[Hv&Lv]

I was always nervous when I had to get an inspection and there were obvious issues.
Not that I did the original installs, but that the inspector would look and say something about the old work.

I was adding a circuit only for a customer once. When it was time for the inspection, the inspector went crazy over two ground rods at the meterbase. My work was nowhere near the meterbase. He would not pass the work until the rods were installed. I argued because it wasn't in my scope in the permit, and I hadn't priced that additional work. Customer wasn't thrilled either, and told me he was priced for the circuit being installed only, the rest was on me. Wanting my money and to get out of there, I ended up driving the rods.

And people wonder why the price goes up if they want an inspection on the work..

Before I got out, I did more work without an inspection than I did with an inspection just to avoid things like that.

 

[kwired]

I agree. The installation being discussed is not standard, and raised flags with the OP. It might also raise flags with the inspector.

I'm just saying that I wouldn't lose sleep over this installation.

If it were my job, I might want to get a closer look to make sure that there weren't dangerous errors in the installation, such as improper strain relief for the flexible cord, or incorrect splices from flexible cord to tank wiring, but I don't believe this is an inherently unsafe setup.

-Jonathan

cord connected or not there isn't a problem with connecting a 240 volt heating element to 120 volts, you just get less heat out of it.

I have one coming up where they are using a 277 volt rated WH, but will be connected to 240 volts. I don't know the cost difference or other reasons why, this one is designed to have upper and lower elements run separately but can run at same time. I think the decision was based on increased recovery time but at same time just all in one tank instead of using two conventional 4500 watt units. Can't recall exact nameplate data but do remember it would need a 50 amp circuit. Watt input overall is still in similar range as what would have been with two regular 4500 watt units, just now with single but larger supply circuit instead or two smaller supply circuits.

 

[ptonsparky]

I'll bet they don't have much of an issue with lime buildup on the element or in the tank.

 

[kwired]

I'll bet they don't have much of an issue with lime buildup on the element or in the tank.

They just get more buildup on shower walls, in the dishwasher, in sinks toilets, etc. instead.

 

[PaulMmn]

I'll bet they don't have much of an issue with lime buildup on the element or in the tank.

If the thermostat is set for 100* water, you're still going to get 100* water, and all the lime that goes with it!

 

[Jraef]

If the thermostat is set for 100* water, you're still going to get 100* water, and all the lime that goes with it!

In theory, yes, the main thing that changes is how long it will take to get to 100 degrees. But the other thing that changes is the "watt density" of the heating element, relating to the surface temperature that it reaches. You have the same amount of surface area of the heater element, but at a lower voltage, you have lower watts, so the watts-per-square-inch of that surface is lower. That can help prevent scale buildup on the element itself.