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Electrician help! [Archive] - StangBangerz Forums

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Kevin Doe
03-26-2007, 10:58 AM
About a year ago I installed a 100A subpannel in my garage. I'm having some issues. Here is what I did.

I ran a #2 Al SE-R. It has three #2 and one #4. My home has a 250A service. In my main pannel, the neutral bus bar, and ground bus bar is the same physical bar.

I talked to the county inspector, and he told me how to hook it up. I also bought the 2005 NEC code book and read it cover to cover. I had a permit and had it inspected and it passed just fine. He hooks are like this.

The ground and neutral are on the same bus bar in the main pannel. In the subpannel, the ground and neutral are on seperated bus bars. The inspector said it must be installed that way. I was unsure what why, since they're basically the same thing because in the main they are on the same bar. Oh well, I did it how he said.

I installed 6 seperate circuits. Two 20A outlets, one 20A hardline for a compressor, a 240V 30A welder outlet, and a 240V 30A to an electric heater hardwired. I used the appropiate sized wire to meet code for each circuit.

Now for the problem.
Everytime I use a 15A tool (chop saw, compressor), it pops my breaker the first time I try and use the tool. So I go and switch it back on, then start the tool again and its fine.

If I plug the same 15A tool into the existing house garage wiring, it never breaks the 20A breaker.

I'm using SquareD 20A breakers. I'm assuming that the initial spike of current in the tool is what pops the breakers. Are new breakers just so fast acting that they pop on the spike, whereas the older house breakers are slower to react and don't pop? Is there anyway to get around this?

I'm really stumped. I've double checked everything to make sure its to code.

Thanks,
Kevin

Black Horse
03-26-2007, 11:57 AM
Did you use ground fault breakers?

Kevin Doe
03-26-2007, 12:03 PM
No, I don't have ground fault breakers. I have GFCI outlets installed on every 120V garage outlet though. Those never have any issues, just the breaker poping every time I start up a tool for the first time or so.

PaulFiveOh
03-26-2007, 12:42 PM
It sounds to me like the initial current spike when turning tools like those on is the reason......but....something else is wrong when that situation occurs only on the sub panel.

Kevin Doe
03-26-2007, 12:44 PM
I'm thinking that maybe the newer breakers (2006 technology) are much faster reacting than a 1982ish breaker. I wonder if "slow blow" breakers are available. Shit, I wonder if thats even safe.

Kevin Doe
03-26-2007, 01:02 PM
I just got off the phone with a SquareD tech rep. I was right, he said tools such as an electric compressor, and chop saw have huge spikes of initial current for a fraction of a second. Upwards of 100A or more. He said that they offer a line of breakers that can accomidate 400-500A of initial spike and still have a 20A steady state breaking capability. He said they are the High Magnetics line (HM) of their breakers.

I'm gonna grab one of those, and see if it does the trick. Nothing pisses me off more than spending $500 to run my own 100A service to the garage and have the breakers trip all the time.

Timido
03-26-2007, 03:15 PM
Let me know if that works cause my 110 compressor does the same thing in my detacted garage.

Kevin Doe
03-26-2007, 03:58 PM
Will do, I probably won't fuck with it for a few days though. Ice and elevation are my best friends right now.

08 Vette
03-26-2007, 04:18 PM
Let me know too! Mine does the same thing. It a 150 A Square D also.

Tim