Garage power question

shoothebunnies

Went out to the garage this morning and had no lights. Checked the panel and neither breaker was tripped. Nothing plugged in. It's an old garage with one pull chain single bulb light and one outlet.

Went in the house to the main panel (runs from there to the garage) and the breaker was tripped. It occupies two slots and is 30 amp on each slot. It says internal common trip. Switched it back on and it buzzed and tripped immediately. Went back out to the garage and shut off the two breakers in the panel out there, came back in and same thing.

Can these breakers go bad?

If so are they hard to change?

Thanks in advance for your help.

joecaption

That sounds more like a dead short.
Been doing any electrical work? Any digging or planting been going on?
Been using any space heaters?

k_buz

Turn all the breakers off in the panel in the garage. Turn the breaker that has tripped back on. If it trips, its most likely a bad underground. If it holds, turn the breakers in the garage on one by one to see which circuit is giving you problems.

I am assuming its a bad underground.

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shoothebunnies

Joe - None of the above. I was in the garage last weekend and changed the oil in the car and had power. When I am out there I run an extension cord with a light so I can see under the car etc. But everything was unplugged and put away when finished.

There would have been power to the light and the outlet but nothing plugged in or drawing current.

shoothebunnies

Did what you instructed, tripped immediately. Saw small sparking when it tripped to I took the panel cover off and switched it again. Sparking seems to be coming from in between the two sections of the breaker. The lights dimmed when it tripped as well.

Might be stupid question here but what is a bad underground? Just what it sounds like? How does that just happen?

k_buz

I am assuming that the wires for your garage are buried underground...either in conduit or rated to be direct buried. These things happen. Being from WI, my customers usually notice problems in real early Spring when the ground is the most saturated.

As for why? There are a multitude of reasons. The metal conduit corroded away and now there is damage to the wires. Shifting of the conduit/wires underground due to freezing/thawing. Something hit the underground like a shovel. I can usually show homeowners the problem when I dig it up, assuming I take the same path as the old underground.

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shoothebunnies

If the breaker is off then I shouldn't have to worry about any other problems with that circuit correct? Or should I turn off the main and unhook the garage circuit from the panel to insure safety?

I am leaving for 2 weeks today and don't want to have to worry about it while I am gone.

k_buz

Just turn off the breaker that is tripping in the main panel.

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shoothebunnies

Is there a way of disconnecting the wire from the panel inside and the panel out in the garage to test it short of just trenching everything up and tearing out the floor in 3 rooms of my house to get to the wiring as it passes underneath?

k_buz

You could try to follow the wiring to see if there are any splices, but you have pretty much just proved the wiring between the house and garage is bad. Where it went bad would be difficult to find. There are toners available that can help find a break, but if the wires are not completely broken, even those won't be of much use.

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dmxtothemax

YES !
start by dissconnectting the wires from the load side of the
relevent breakers in the main panel.
Turn off the breakers in the sub board in the garage.
Now put a volt meter between the neutral wire and one of the hots,
Check for sure its dead !
Check the other hot the same way.
If both are dead,
then test with an ohm meter between each hot and neutral.
it should be very high or infinate.
If its low then the cable is shorted or damaged.

Be super carefull when working around panels.
Take all the usual precautions and more if you can.

report your findings please !

Stubbie

By doing what K BUZ suggested he has proven he has a phase fault in the feeder. You can test all you want it will only prove the same thing you already know. You can investigate the wiring where it is accessible indoors and out but any thing underground is pointless. If it is in conduit try to use the old wire to pull in the new replacement wire and a bonus occurs ... you get to see where the wire failed .. If it is direct burial get the shovel or trencher and you know the rest ...

shoothebunnies

Problem is it runs under 3 rooms in the house without access so either the floor comes up or I will have to re route. No luck on conduit as far as I can see either direction.

JuzRick

If your uncertain about what to do with correcting the problem, I would suggest you consult with a qualified electrician to assisting you where you will be on the right track, resolving the problem. For it could as well be the subpanel in the garage is bad to which could cause all the above by triggering the problem. Dealt with that to many times here in my city.

Call a qualified electrician....

Stubbie

I think you need to re-read the thread ...