Faulty main breaker?

I have a westinghouse 125A serice panel. Over the past week or so, the main breaker has suddenly started tripping. At first it seemed to be only when the clothes dryer and a number of kitchen appliances were running, but as of yesterday just the dryer alone is now tripping it. There is no additional load on the system and all connections in the panel appear to be tight with no sign of excessive heat. When I searched the forum for "main breaker" topics there appear to be a number of different possibilities that could be causing this, but none precisely like mine. Given my scenario described above, any thoughts or suggestions on the the most likely culprit(s)?

Thanks in advance!

Bret

 

Bret,

You say that there appears to be no loose connections. The only way to make sure is to turn the power off and physically check all of the connections.

Your problem sounds like it could very well be a loose connection since it is getting worse over time. When a connection is loose and starts to fail it will begin arcing, when this happens it will get worse each time any kind of load is applied. The loose connection may not be in the service panel itself, it could be in the meter socket as well. This is something that can't be inspected with a simple visual inspection. The connections to the main breaker or main buss will need to be checked against the torque value suggested by the maufacturer. This information can be found on the label located either inside of the cover or inside of the panel itself.

Yes, your main breaker may be bad or going bad but my money would go to a loose connection first. The only correct way to check is to make sure that these connections are physically tight and torqued to specification. Don't rule out the fact that it might be a neutral or grounding connection that is loose but, I would figure that you have an ungrounded conductor that is loose.
Hope this helps.

 

I agree with sparkone42, I suspect also a loose connection again most likely on the hot conductor but also may be on the neutral conductor. Most likely the loose connection may be inside the main breaker where the main breaker connects to the buss bar or where the main service conductors are connected to the line side of that main breaker. Next choice as sparkone42 mentioned inside the meter base. One choice that sparksone42 mentioned is also if you have an overhead service it may be a loose connection at the point of connection at the weatherhead.

Sometimes you can quickly center on the loose connection by looking for discoloration of metal connections due to heating caused by the loose connection or bubbling of the insulation near the point of connection of a conductor.

As sparkone42 mentioned the only true method of confirming good connections is to de-energize and tighten the connections looking for a connection that is not tightened enough.

Also if you find a loose connection that has bubbling of insulation or discoloration be sure to cut off the damaged part back to a part of the conductor that is in good condition and undamaged. A damaged lug or conductor will have you back doing it again soon if you don't correct the damage found making a good connection.

Let us know what you find

Wg

 

Thanks for the suggestions. I have underground service. When I get home tonight, I'll shut off the power at the meter and check all the connections in the service panel. I'll let you know how things shake out.

Cheers,

Bret

 

Well, it must have been my last home that had the switch between the meter and the service panel. I would have sworn there was a switch in the service panel supply line! Now that I have no way of shutting down the power to the service panel myself, it looks like I'm going to have to get the power company out to do that for me. If that's the case I'll probaby be required to also enlist the services of a certified professional. In any event, I'll keep you posted on what the problem turns out to be.

Cheers,

Bret

 

Success! Yesterday someone decided to fly their hang glider into the power lines and knocked out the power for about three hours. Being the opportunistic guy I am, I went ahead and checked for loose connections and sure enough, both main breaker supply connections as well as a number of individual circuits were loose. All tightened up now and everything is back to normal. Yes, I did confirm with the line crew how long the power would be out, since they first had to get the guy in the hang glider down. Thanks again for all your guidance and suggestions.

Cheers,

Bret

 

Glad you were successful.

Would have liked to see you ask the power company to cut your power for minor repair and diagnosis and had your meter base connections checked by them at the same time. This would have given you time to have cut back the damaged wire that was heated by the loose connections and made new connections with new part of the conductor that was not exposed to that heat. Better safe than sorry.

Good Luck

Wg

 

How did the hang glider person come out ? good learning info there. (never fly near power lines)

 

Thanks WG, I did carefully inspect the leads for excessive heat and there was absolutely no sign whatsoever that any of the lines had overheated. Don't get me wrong, I completely understand and appreciate your suggestions and guidance, unfortunately, co-ordinating myself, an electrician and the power company with my schedule is almost impossible so I thought I'd take advantage of the situation as best I could. If I encounter similar problems in the future, then I'll definitely have to have the meter base connections inspected.

As far as the guy who hit the powerlines is concerned, amazingly he came out completely unscathed. It was definitely his lucky day.

Cheers,

Bret