5 replies to this topic

[jrbirdman]

Ok, a newbie here but hoping to get some good advice (can't seem to get it from the repair people who show up). We're talking about a GE wall oven JT915 series. The oven was relocated from the kitchen to the basement in preparation for the kitchen rennovation. 220 line was brought to the new location by the contractor, he hooked up the oven and ... nothing. Repairman came, said the wiring was done wrong and blew out the erc board (resistor had "burn"marks on it), rewired and ordered a new one. Came a week later, put it in and nothing. Ordered another one, another week and same thing. This time he tests the voltage (getting 120 from the red leg and 117 from the black leg) and calls up his "expert" who says the erc board needs 120 from the black leg to "turn on". Repairman won't come back until voltage is "fixed", but electrician says that his claim is garbage because in every 220 line, each leg will vary betwen 110-120. Seems I'm caught in the middle here.

Is there something else that could have blown that can be tested. Repairman said that power is going to the erc (tested the L1 connection) but its not turning on. Any advice, suggestion would be really appreciated as I'd hate to get rid of something that can be reasonably repaired.

Thanks in advance.

[Samurai Appliance Repair Man]

This time he tests the voltage (getting 120 from the red leg and 117 from the black leg) and calls up his "expert" who says the erc board needs 120 from the black leg to "turn on". Repairman won't come back until voltage is "fixed", but electrician says that his claim is garbage because in every 220 line, each leg will vary betwen 110-120. Seems I'm caught in the middle here.

These voltages are called nominal voltages because they are not given as exact specifications; there is an allowable +/- variance. 117vac is close enough to 120vac for the board to work properly.

Sounds like you have a coupla doofusses working for you. The appliance guy is a parts changing monkey who doesn't understand electricity and undoubtedly can't really troubleshoot a circuit with a diagram and meter-- basic skill Numero Uno in the appliance repair trade.

Do any of the lights come on in the range? How about the surface burners, which are independent of the ERC? If the surface burners don't work either, then I think you have an open neutral. You can have voltage all day long but without a neutral for the return leg, you don't have a circuit and nothing will work. I've seen many electricians forget to wire up the neutral for a circuit in the circuit breaker box. They get L1 and L2 tied into the breaker but seem to forget to tie the neutral into the neutral bus. Sounds like this may be what's going on here.

[Comstock_Services]

Do you have a voltage meter or multi meter? If you loose neutral, everything will be dead, including the cavity light. but if the neutral is good the cayity light should work. you did say that the repair man, had 110-120v to the black leg at the back of the control. but was he testing to ground or neutral? this matters because, you can test to ground and get voltage, even if the neutral is bad.

[jrbirdman]

Thanks for your reply. Couldn't agree more with your description of my "professionals".

We're dealing with a wall oven, so no range parts, etc to test. As far as the neutral is concerned, the multimeter votage readings were measured at the plug connecter (black-white and red-white). I don't think we would have gotten those measurments without the white being a good neutral.

What am I missing here?

[jrbirdman]

Resolved. Thanks all for your help. You were both right on target.

i traced the wiring back and all seemed in order until I got the the box where the romex and bx were joined together and discovered that the white neutral (coming all the way from the oven) was connected to ... nothing. The romex was a 3 wire cable and they hooked it up as 2 hots and a ground wire connected to the junction box. I unscrewed the ground wire and connected the neutral to the ground. The voltage jumped to 125 each leg and the oven powered right up.

what was throwing everyone off was that when the voltage was tested at the plug connector using red-white and black-white, it was displaying voltage. If that white neutral was never connected, then why was it acting as ground? Maybe because its bx cable?

Anyway, thanks again.

[Samurai Appliance Repair Man]

The voltage was still present but, without a neutral, there was not return path for current and hence no circuit. For electricity to do work, there has to be current flow and that means there has to be a return path. That's what the neutral does. Sometimes, a floating neutral will cause you to read "junk voltage" but not always.

In cases like this, I'll test the power supply with a clip-on lamp just to make sure I have a complete circuit.

Checking voltage is good but checking current is supreme.