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-   -   Don't understand this breaker tripping problem (http://www.diychatroom.com/f18/dont-understand-breaker-tripping-problem-65929/)

majesticjess 03-03-2010 10:32 PM

Don't understand this breaker tripping problem
 
Brand New Circuit: 20A AFCI breaker, 5 outlets, switch controlling a ceiling light with a 100w bulb in it.

Breaker does not trip:
A. Ceiling light on. OK.

B. Ceiling light on and 500w work light plugged in and on. OK.

C. Ceiling light on and 2 500w work lights plugged in and on. OK.

D. Ceiling light on, 2 500w work lights plugged in and on and vacuum plugged in and running. OK

E. Ceiling light on, 2 500w work lights plugged in and on, vacuum plugged in and running, and circular saw running. OK.

F. Ceiling light on, 2 500w work lights plugged in and on, belt sander running. OK.

G. Ceiling light on, 2 500w work lights plugged in and on, hand grinder running. OK.

H. Ceiling light on, 2 500w work lights plugged in and on, right angle drill running. OK.

Breaker trips:

I. Ceiling light on or not on and nothing plugged in and running except DW235G drill. Breaker trips.

J. Ceiling light on or not on and nothing plugged in and running except the miter saw. Breaker trips.

When I say "running" it means tool is rotating but I'm not cutting, drilling, or grinding anything.

I have performed the experiment with the DW235G drill plugged in each differnt outlet, break still trips. Tried a couple differert outlets with the miter saw.

I have used the miter saw and DW235G drill for years on other original circuits in this house with no problems.

Porter Cable circular saw: 15A, 2 prong plug.
Porter Cable belt sander: 7A, 3 prong plug.
Milwaukee hand grinder: 12A, 2 prong plug.
Dewalt DW123 right angle drill: 11.5A, 3 prong plug.
Vacuum cleaner: No tag so not sure how many amps, 2 prong plug.
Dewalt DW235G drill: 7.8A, 3 prong plug.
Dewalt miter saw: 13A, 2 prong plug.

It seems like there are two possibilites:
1. Something weird with the miter saw and DW235G drill.
2. There is some type of problem with the circuit.

It is difficult for me to imagine a problem with the circuit as it is a simple circuit and I was meticulous when wiring it, but who knows, something could have happened. But it seems that if there was some type of circuit problem that some of my A to H experiments would have failed too.

What is your guess as to what is "probably" going on?

If you think it is a circuit problem, what troubleshooting steps would you recommend to narrow down where the problem is?

Thanks.

Scuba_Dave 03-03-2010 10:37 PM

Some tools will cause AFCI's to trip
Some vacuums will too
Anything that seems like an arc fault basically
Ever seen sparks inside of a drill while using it ?

secutanudu 03-03-2010 11:25 PM

What rooms does this breaker control?

majesticjess 03-04-2010 01:32 PM

Quote:

Originally Posted by secutanudu (Post 409236)
What rooms does this breaker control?

A bedroom I'm building.

secutanudu 03-04-2010 02:10 PM

So the devices that are causing the breaker to trip won't be in there routinely, right, once the rooms are done? Why not just replace it with a normal breaker until you're finished?

Affordable7 03-05-2010 08:30 AM

If I'm understanding the issue correct...you have 3100 watts of energy in the form of lights off a 20 amp breaker to begin with? Watts divided by Volts = Amps. 3100 divided by 120 equals around 25 amps? And this circuit never popped before? You are blessed my child...or maybe not...it may have melted your buss bar on the circuit panel. However, throw in the mix of a 15 amp motor with another 12 amp motor and 2500 watts at same time? You're extremely lucky your house hasn't burned down. That breaker should have popped with just the lights on...let alone another 27 amps load.

Scuba_Dave 03-05-2010 09:41 AM

Quote:

Originally Posted by Affordable7 (Post 409899)
If I'm understanding the issue correct...you have 3100 watts of energy in the form of lights off a 20 amp breaker to begin with? Watts divided by Volts = Amps. 3100 divided by 120 equals around 25 amps? And this circuit never popped before? You are blessed my child...or maybe not...it may have melted your buss bar on the circuit panel. However, throw in the mix of a 15 amp motor with another 12 amp motor and 2500 watts at same time? You're extremely lucky your house hasn't burned down. That breaker should have popped with just the lights on...let alone another 27 amps load.

Read it again...he's testing the circuit each time, he has (2) 500w lights that he plugs in as a Test....(A-J) each one is seperate a Test
I'm not sure where you are getting 3100w from (2) 500w lights & a ceiling fixture :no:

and if you are really adding up the 7 tests = it's over 6700w all together in lights :whistling2:

majesticjess 03-05-2010 11:54 AM

Quote:

Originally Posted by secutanudu (Post 409479)
So the devices that are causing the breaker to trip won't be in there routinely, right, once the rooms are done? Why not just replace it with a normal breaker until you're finished?

Yea, I'll just run those tools off of an extension cord from another circuit for now. I just wanted to make sure there wasn't a problem with the circuit that I didn't understand. Thanks.

This seems like this might be a annoying problem for folks in the construction trade. They are inside working on building a new house (drywall, finish, whatever) and many/most of the circuits in the house (nec 2008) are AFCI and one or more of their tools trips the breaker in the room they are working on...

kbsparky 03-05-2010 06:32 PM

Does the chop saw trip when you switch it on, or off?

I've seen the models with the electric brake trip out AFCI breakers. Seems that the electric "brake" is nothing more than slamming it into reverse for a split-second to slow down the rotating blade.

That can wreck havoc on the brushes and an AFCI senses problems so it trips. :mad:

Leah Frances 03-05-2010 07:30 PM

Jess- I can't use either my table saw or my miter saw on an AFCI protected circuit. Turned the switch on and circuit went 'POP'. Funny part was I had to post here to figure it out. So, you are in good company. :thumbup:

Scuba_Dave 03-05-2010 07:42 PM

Quote:

Originally Posted by majesticjess (Post 410006)
This seems like this might be a annoying problem for folks in the construction trade. They are inside working on building a new house (drywall, finish, whatever) and many/most of the circuits in the house (nec 2008) are AFCI and one or more of their tools trips the breaker in the room they are working on...

I'd bet if they have problems they use reg breakers until its time for Inspection
A lot use cordless now, or run tools from a Gen
If there is a Temp power pole for new construction it would (should) be GFCI


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