replaced receptacle now pops breaker under saw load

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Old 01-15-08, 08:51 PM
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replaced receptacle now pops breaker under saw load

I replaced two 15-amp receptacles in my garage with two new ones (long story- so they would all look new and match). They, like the originals, are in a double box, and they are "end of the line" on the circuit. The first is wired to the line in side and the second is wired to the first's line out side with a little black wire and a little white wire. The breaker is a 20 amp breaker, but like most houses' I have seen, the 20 amp circuits still have 15 amp rated receptacles (i.e nobody in residential seems to use the 20 amp receptacles with the T-slot.)
Anyways- my primary use had been my newer model 10" miter chop saw. Used it fine for months and never had a problem. Now it pops the breaker the second I touch the saw's power trigger. Meanwhile my shop vacumn in the same outlets (I tried all four) works fine, as do the other things on the circuit (light loads like a single light and a unit heater's transformer), that is until the saw trips the breaker. I did not change anything except the actual receptacles.
Please help, as I lost their main function with my little aesthetic fix.
 
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Old 01-15-08, 09:08 PM
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The first is wired to the line in side and the second is wired to the first's line out side with a little black wire and a little white wire. The breaker is a 20 amp breaker
,Line in, line out? Are these GFCI receps? If not, there is no line in and no line out.

You connect the colored wire to the bras screws and the white wires to the silver screws. and the green wire (or bare) to the green scrrews.

but like most houses' I have seen, the 20 amp circuits still have 15 amp rated receptacles (i.e nobody in residential seems to use the 20 amp receptacles with the T-slot.)
this is acceptable as long as there is more than one recep on that breaker.
QUOTE] Now it pops the breaker the second I touch the saw's power trigger.[/QUOTE]I would go back and re-check the connections. Make sure none are loose.
 
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Old 01-15-08, 09:33 PM
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I looked at some outlets at a "home center" the other day, and on the inside of the neutral slot on the 15a receptacles, you could see a "T" connection. It looks like they just made one base for the receptacles, then the manufacturer could put a 15a or 20a face on it.

Are you using the shop vac at the same time as the saw? If so, you are probably overloading the circuit.

Does the saw work on another circuit? If not, the saw may have a fault.

Are there multiple circuits? Did the old outlets have the tabs broken?
 
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Old 01-16-08, 05:26 AM
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The saw, like all motorized equipment, draw a high current at startup. Over time this current will increase as the motor gets older and needs more current to get it started.

If the saw does not trip the breaker on another circuit then your circuit breaker is getting weak.

You might also want to verify that all your connections are tight.
 
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Old 01-16-08, 06:27 AM
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Everything else works fine in the new receptacles? Does the saw work in other receptacles? Sounds like the saw is defective. It is the breaker that is tripping and not the GFCI correct?
 
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Old 01-16-08, 09:46 PM
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my bad:
this 20 amp circuit goes from circuit breaker to a single bulb light to the furnace transformer to this two duplex receptacle box (so four "outlets"). The black and white wires go to the first receptacle and then a short black and a short white wire goes from that recpetacle to the last one in the circuit right next to it. ALL FOUR OUTLETS TESTED "CORRECTLY WIRED" with my little three prong outlet tester. These are NOT GFCI outlets (so ignore my line-in/line-out from my first post.) The saw is 9 months old and works great on another circuit. The saw and vacumn were not on simultaneosly, I was just showing that in addition to the tester, the outlets also powered the vacumm fine. No idea about the tabs (?) on the old receptacles. They are long gone, but I never had a problem with tabs when re-wiring before. I think I covered all the replies here.. it sounds like it is either the breaker or the connections, but neither seems likely when you consider that the vacumm works fine.
If you have any other ideas please reply.
Thanks
 
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Old 01-16-08, 10:31 PM
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You mentioned furnace transformer?

Is it possible the heat was on when you used the saw?

Have you tried the saw in a different outlet?(on a different breaker of course) is the saw 's cord two or three prongs?

I just got a 10 inch mitrre chop saw for X-mas, and was shocked(surprised, Not ZAPPED) when it "pulled down' all the lights in my garage.Hefty little piece of current draw there!
I must agree with Racraft here...Your breaker is wearing out.

But also as Nap mentioned, double check the connections, for accuracy and tightness. If this is indeed a "Two Pronged" cord, its double insulated and grounded internally, In which case a reversed or loose connection could wreak havoc. Hot (black) to Brass Screws, Neutral (White) to silver screws. Ground to Green screw throughout the loop.


ooops, Just realized something......Double check the connections.......If you wired the recepts in series accidentally, the vacuum would work , but the high current draw from the saw definitely would not. Also, if you mixed up and had a black and a white on the same "SIDE" of the second outlet, pulling the trigger on the saw would , In reality , Complete a 'Short circuit" thru the motor windings and trip the breaker.
 
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Old 01-22-08, 11:40 PM
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Thanks for help

I checked it out (which I should have done first, except I was SURE I had wired it the same as I had found it). On the 2nd receptacle in the box (last in the series?) I had wired the white wire from the first receptacle to the lower silver terminal and the black wire to the upper gold terminal. I switched the black to the lower gold terminal and it tests "correct' and works fine with the chop saw.
 
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Old 01-23-08, 05:26 AM
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Originally Posted by AKRBT View Post
On the 2nd receptacle in the box (last in the series?) I had wired the white wire from the first receptacle to the lower silver terminal and the black wire to the upper gold terminal. I switched the black to the lower gold terminal and it tests "correct' and works fine with the chop saw.
This fixed nothing. You have some other problem.
 
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Old 01-23-08, 11:16 AM
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I agree with ^^^^^^^^.
 
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