Cook Top Not Working Quite Right


Old 11-04-05, 10:41 PM
Thread Starter
Join Date: Nov 2004
Posts: 17
Cook Top Not Working Quite Right

I have a electric cook top that has the glass top with coils beneth. When one element is turned on, it seems to run fairly well . But when turn on a second element , there is signifcant reduction inthe heat from the first.

What could be the cause of this.

It may not be related, but when my wife used the iron upstairs, all the lights upstairs dim.

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Old 11-05-05, 07:00 AM
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
Your issues may or may not be related, and may indicate a serious problem.

Whenever electricity flows through a circuit in your house, you get what is known as 'voltage drop'. The greater the current flow, the greater the voltage drop. This voltage drop is essentially the power lost in the components and wires feeding the load.

When your wife turns on the iron, it increase the amount of current flowing in the circuit which feeds the iron. This means more voltage drop on that circuit. _Everything_ that shares the circuit will be affected by this change in voltage drop, so you will expect any lights which share the circuit to get a bit dimmer.

Something that you should note is that your entire house is essentially supplied with a couple of large circuits. When you turn on anything (even a small clock radio), everything else on that circuit will see a slightly lower voltage. You just don't notice such small voltage drops.

So there will always be some voltage drop. However an unexpectedly large voltage drop, a _new_ voltage drop, or a voltage drop that affects multiple circuits may indicate a serious problem.

A loose connection is the concern here. A loose connection can impede the flow of electricity, causing excessive voltage drop while generating lots of heat in the process. This can get dangerous quite quickly. In particular, your cooktop should be wired so that voltage drop is not noticeable. I would be concerned that one of the connections to the cooktop is loose. It is also possible that one of the supply connections to your house is loose. Finally, if your electrical service is old, you may simply be seeing voltage drop caused by small service wires and a small transformer.

Do any lights in your house dim or get _brighter_ when you use your cooktop?
Do you have fuses or circuit breakers?
Are all of the lights in the 'upstairs' on the same circuit breaker or fuse?

Old 11-05-05, 09:13 PM
Thread Starter
Join Date: Nov 2004
Posts: 17
Thanks so much for the reply,

Your sense of urgency prompted me to go turn off the breaker and start looking at the connections.

It wasn't a pretty sight. This remodal which was done prior to our buying the house, was not down right. :
1. The cable was running into the junction box on the stove right over the metal edge of the hole.
2. There was a junction box clamp , but it was inside the junction box clamped to the cable. It was not the right size for the hole and there was not jam nut in sight.
3. I opened up each of the nuts.
The White had a red nut jammed with 3 large gauge wires (will replace with a larger one)
The black has the wire from the stove cut short so I could see nut thread impression all the way around the black from the house
4. There was a hole in the black wire from the junction box screw.

So off to the the hardware store in the morning to buy the right size parts so I reterminate the wires and put it back together right.

Regarding your quesitions:
Do any lights in your house dim or get _brighter_ when you use your cooktop?No. There is no dimming. That must mean the issue is isolated to the stove circuit.
Do you have fuses or circuit breakers? Breakers 200AMP service
Are all of the lights in the 'upstairs' on the same circuit breaker or fuse?
I am new to the house so I have not mapped the circuits yets. Does dimming indicate an overloaded circuit?
Old 11-06-05, 05:46 AM
Join Date: Jan 2004
Location: Oregon
Posts: 1,219
It sounds like you've located the problem with the cooktop. Given the problems that you've noted, I'd strongly suggest that you investigate the rest of the wiring quite closely.

I agree that the stove problem is isolated to the stove.

Dimming does not indicate an _over_loaded circuit. Dimming indicates a heavily loaded circuit with large voltage drop.

The dimming could simply be caused by a long run of #14 wire feeding this circuit, entirely possible because old wiring is like that.

The dimming could also be caused by a bad connection, similar to what you found feeding the stove.

The fact that 'all' of the lights in the upstairs would dim suggests that far too much is on a single circuit, and my guess is that the entire second floor was on a single circuit, and that the electrical main panel was updated but the old circuit simply connected.


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