[andrewcocke]

Hello:

Isn't it true that everything electrical should be grounded by code?

I ran in to a 240 volt 50 AMP booster water heater today, that blew some wires in a junction box, I noted that there was no ground wire coming to the unit, just two hot legs.

I told the customer that he will need to get a licenced electrician in there to fix the grounding issue before I could repair the booster. Im just wondering if I made the right call.

Personally, I won't work on a piece of equipment if I find out its not grounded, the ground wire has saved me from getting some serious shocks a few times.

Also, the junction box that had the wires short circuit was a standard metal box located right behind the dishwasher. I theorize that the box probobly got wet and shorted out, I also recommended he get a water tight box.

[omzig]

Yes, it should definitely be grounded. The water heater doesn't need a neutral, but it should have an equipment ground. The box should be grounded with a pigtail to a screw, and there needs to be a grounding conductor from the junction box to the unit. If there is some type of flex conduit going from the box to the unit, it cannot act as a ground because the unit is more than 20A.

[tkrussell]

What type of raceway were the two hot legs in? You will not necessarily always see a green or bare wire ground , because all common metal raceways are listed to act as an equipment ground, such as BX cable, EMT, rigid metal conduit. IMC, and flexible metal conduit 6 foot and shorter with listed fittings.

Even thou the water caused the two hot wires to short out and burn between each other, and did not short out to ground, which is very possible.

If your not sure if there is a ground , test across a hot leg and the metal box or raceway, and if you read full voltage, then it is grounded.

Even thou a continuous green ground wire is preferred or typical, it is not the only method of equipment grounding allowed.

[andrewcocke]

Other than the junction box, which is standard galvanized steel, the conduit from the breaker box to the junction box is PVC, the conduit from the junction box to the booster is a pvc whip. There appears to be a grounded wire in the junction box, but Im really not sure, all of the insulation of ALL wires are melted off in the JB. But Im sure there is no ground wire going to the booster.

At this time, I can't check for voltae at the booster until I get the JB fixed, as it obviously blows the breaker every time I turn it on.
Once they get that fixed, it will most likley get grounded. I was thinking the shower this morning that the unit might ground though the water pipes. (although might not be legal, still might work) in a worst case scenario.

[omzig]

I thought flexible metal conduits (FMC, LFMC, FMT) couldn't be used as a ground if the overcurrent device is more than 20A.

250.118(5)(b), 250.118(6)(b), 250.118(7)(a)

[tkrussell]

Yes correct, just listing the raceways that are allowed without getting into all the exceptions, that may or may not apply to the question.

[andrewcocke]

Well, in any event, the flex conduit isn't metal. The health department forbids that, it has to be something that won't rust.

In any event, Im pretty sure this whole line will have to be redone, with a new junctionbox. This one here is just right under the dishwasher, by the pop off valve for the booster, and I just found out from an employee there that there is a shut off valve next to it that aparently started leaking water all over it a while back, which probobly contributed to this problem.

[tkrussell]

Unbeliveable some of the stuff out there. Non metallic flex without a ground wire! And on a commercial booster heater. Now if there is someone that should loose their license, if he had one.

Too bad health officials did not know how to look at electrical work, but I know they have enough to look for, I do understand the need for to eliminate rust. Nothing better to work on is rusty equipment all caked with grease.

I always use NEMA 4 enclosures in commercial kitchens, even if the valve did not leak, they should be swapping the floor often. Abd esp under a dishwasher.

[andrewcocke]

Well, the guy that runs it is a good ol'boy. He just has a restaurant in a very old building. Normally, when we bring these kind of things to his attention, he is quick to have the issues remedied.

And I didn't run into any slack the other day, but I do occasionally run into customers who don't like news like this. But I figured that this setup was a hazard plain and simple.
The call that came is was a rinal rinse to low, noticed that the booster breaker had tripped, went to reset it, then went over to the booster, contacter pulled in and it was pulling amps.

No sooner than I said "I beleive its fixed", we heard the loudest!! POP!! It was heard all the way in the dining area and made all the lights flicker. I had thought an element blew, but I couldn't find anything wrong with the elements, nothing was smoking on the booster. Finally, something told me to check the JB, and there is was, all wires smoked! The wire nuts were nothing but a melted gob of plastic on the bottom.

Anyway, boss said we can't fix that, anything past the cord or supply line to the machine, we have to call in an electrician.

What an exciting day.