Lose wire

Status
Not open for further replies.
S

SAP

Senior Member
Location
Fresno Ca
This might be a no Brainer , but here it goes anyway, can a lose connection to a breaker, make that breaker trip thanks, I have a oven on a 30 Amp beaker it was tripping on the home owner connection was lose arching thanks
 
SAP said:
This might be a no Brainer , but here it goes anyway, can a lose connection to a breaker, make that breaker trip thanks, I have a oven on a 30 Amp beaker it was tripping on the home owner connection was lose arching thanks
Click to expand...

Breakers are thermal magnetic so anything that makes them get too hot will cause a trip.
 
SAP said:
This might be a no Brainer , but here it goes anyway, can a lose connection to a breaker, make that breaker trip thanks, I have a oven on a 30 Amp beaker it was tripping on the home owner connection was lose arching thanks
Click to expand...

Yes.

The loose connection, whether arcing or glowing, will create heat. That heat will get into the thermal trip mechanism of the breaker and have the same effect as too high a current, causing the breaker to trip at a much lower current than rated.

Putting the breaker panel is a very hot location will have a similar effect.
 
It is not especially likely, but it is possible.

The arcing does generate a small amount of heat but the copper wires are very efficient heat sinks.

I would not be counting on it as a safety measure though it could happen.

I would be more inclined to suspect that the arcing was causing surges of startup current that might be what is actually tripping the breaker, as opposed to the heat being generated by the arc itself.
 
petersonra said:
It is not especially likely, but it is possible.

The arcing does generate a small amount of heat but the copper wires are very efficient heat sinks.

I would not be counting on it as a safety measure though it could happen.

I would be more inclined to suspect that the arcing was causing surges of startup current that might be what is actually tripping the breaker, as opposed to the heat being generated by the arc itself.
Click to expand...

An oven is a purely resistive load. Where would the inrush be coming from?
 
gadfly56 said:
An oven is a purely resistive load. Where would the inrush be coming from?
Click to expand...
Well, the resistance of metal goes up with temperature. It seems to me that a resistive heating element will draw more current when you first turn it on (when it is cold) than it will when it comes up to working temperature.
 
ggunn said:
Well, the resistance of metal goes up with temperature. It seems to me that a resistive heating element will draw more current when you first turn it on (when it is cold) than it will when it comes up to working temperature.
Click to expand...

So a 200 watt light bulb pulls about 1.6 amps at it's operating temperature. When cold, the inrush is about 15X steady state so about 24 amps. Usually you don't trip a 15 amp breaker when you turn on a 200 watt lamp, because the inrush is only for a few cycles. I would think the same principal applies to the oven and therefore you shouldn't expect an issue under normal circumstances.
 
ggunn said:
Well, the resistance of metal goes up with temperature. It seems to me that a resistive heating element will draw more current when you first turn it on (when it is cold) than it will when it comes up to working temperature.
Click to expand...

Negligible for an oven.

Copper: 4E-3 deg C

NiChrome: 0.17E-3 deg C, not much change hot from cold.

Carbon: -0.5 E-3 deg C, lower R with temp.
 
gadfly56 said:
So a 200 watt light bulb pulls about 1.6 amps at it's operating temperature. When cold, the inrush is about 15X steady state so about 24 amps. Usually you don't trip a 15 amp breaker when you turn on a 200 watt lamp, because the inrush is only for a few cycles. I would think the same principal applies to the oven and therefore you shouldn't expect an issue under normal circumstances.
Click to expand...

You are correct, the cold inrush of the heating element should not trip the breaker, even so it would be in the first few hundred milliseconds.
 
petersonra said:
It is not especially likely, but it is possible.

The arcing does generate a small amount of heat but the copper wires are very efficient heat sinks.

I would not be counting on it as a safety measure though it could happen.

I would be more inclined to suspect that the arcing was causing surges of startup current that might be what is actually tripping the breaker, as opposed to the heat being generated by the arc itself.
Click to expand...

It's probably not the arcing that causes the breaker to trip. After it's been arcing for some time if you pull the wire from the terminal you will notice that it's no longer good clean copper but is charred and pitted and no longer a good connection and there is a heat build up at the connection (high resistance ).

On a problem like this I normally change the breaker (they are cheap) and cut back the wire a little to get clean copper.
 
ptonsparky said:
You are correct, the cold inrush of the heating element should not trip the breaker, even so it would be in the first few hundred milliseconds.
Click to expand...
FWIW, the heating element in an oven does not come up to working temperature nearly as quickly as does the filament of an incandescent light bulb, but I agree, it's not likely to trip a breaker.
 
ggunn said:
FWIW, the heating element in an oven does not come up to working temperature nearly as quickly as does the filament of an incandescent light bulb, but I agree, it's not likely to trip a breaker.
Click to expand...

Also, nichrome has a higher room temperature resistance and a very flat temperature/resistance curve and varies only by about 10-20% from room temperature to red-hot.
 
Status
Not open for further replies.
Top