outside elec. outlet exploded

[Barry]

I was using a circular saw to cut some 4x8 sheets of 5/8" fiberboard (not MDF, the less dense stuff). Halfway through my first cut of the day, the blade wound to a stop and the saw appeared dead. Checking the outside outlet I was plugged in to I found a huge black scorch above it and half of the plug was melted. One of the prongs melted off and is stuck in the socket. This outlet is located outside the house but underneath a protected entryway. The house is 10 years old and in good repair.

The saw is a 2hp 10amp. The cord is a heavy gauge (was) in good condition,

40 feet long. Not sure the exact gauge of the cord but it's thicker than the average outside extension cord.

After this incident I plugged the saw into a different outlet (GFCI protected in the garage) with a shorter but lighter gauge cord and proceeded without incedent to rip my five 4x8 sheets. The GFCI never tripped.

Is a 40 foot extension cord too long to run a 10amp saw with? If that's not it, does anyone have any thoughts on what the problem might be? Thanks for any help.

[m Ransley]

Just a defective extension cord, probably the wire was loose in the plug, but running a small gauge cord can ruin a saw, not enough current flows to the motor

[John Grabowski]

Four thoughts come to mind as to what may have caused this:

1. Loose connections inside of the plug of the extension cord.
2. Loose connections on the receptacle.
3. Water on or inside of the outlet.
4. Worn out receptacle was not making good contact with plug.

It could also have been any combination of the four. I think it is odd that it happened so quickly on your first cut.

John Grabowski

[Bill]

I install commercial grade 20 amp outlets in my house (also have 20 amp circuits). These cost $3 each as compared with 69 cents, but I never have such problems with them.

Also for construction work; saws, compressors, etc. I get the largest gauge extension cords I can buy. 12 or 10 ga. (Home deplete your bank account has these [Home Depot])

And if replacing plugs on an extension cord or appliance, I get commercial grade heavy duty plugs which also have a screw down wire clamp.

And I *never* pull a plug out of the socket by pulling on the wire. This can damage the connection between the wire and the plug.

Basically I don't have any trouble.

Note: If the outlet which got fried is a 15 amp circuit, replace it with a

15 amp commercial grade outlet, not a 20 amp outlet. Commercial grade outlets have much better contact with the prongs on the plug. So the plug will not be warm to the touch after use.

[Beachcomber]

Most likely you had the right equipment. Probably what happened was that your outlet had a high resistance connection on it. If it was wired as a poke and stab, this would be a likely cause, although a loose wire on a loose screw could also give you high resistance.

The outlet sat there for years with no problem, but then you plugged in your saw and started drawing high current. The high resistance connection is going to heat up more and more and you saw the result.

Replacing with a high quality outlet and turning those screws tight (with the power off) should solve the problem. Also, heed what the previous poster said. Buy good, heavy duty extension cords. 10 ga is best, minimum should be 12 ga.

Beachcomber

[Bill]

Good point!

I also *do not* wire my outlets by sticking the wires in the holes in the back. I use needle nose plyers to make a round curve in the stripped wire, then screw the wire down tight on the outlet.

[George E. Cawthon]

Just a bad connection--probably the plug in the socket or a short at the plug end of the cord.

For 40 feet you probably want to use at least #14 cord on that saw and you really don't want any cord less than #16 for any distance. Course it isn't 2 hp since it is only 10 amps (probably closer to 1 hp, maybe even 1.25 hp).

I prefer to use a 12 gauge extension cord for anything drawing that many amps, but sometimes use a smaller gauge. You can buy a 50 foot 12 gauge extension cord for $16 when Harbor Freight has them on sale. (or if you hate Harbor Freight enough, go to Lowes or Home Depot and buy the same cord (same color same manufacturer) for $50 or more.

[TKM]

Electricity seems so gentle until something like this happens. You had a short (likely) or an arc on one side of the line (less likely); but both make things hot enough to melt metal instantly.

Once while remodeling an old carriage house, one of the electrical guys wiring outlets inside the building dropped his screwdriver across one side of the line and the neutral in the CB box. I happened to be outside working on the 3-wire feed lines. The current surge and resulting magnetic field caused the lines to jump pulling them away from the building supports. Fortunately, the inside guy was wearing safety glasses. There was molten metal flying everywhere and the screwdriver disappeared. Scary.

TKM

[ameijers]

(snip)

Ran into a similar problem daisy-chaining the 5-buck orange cords to use a leaf blower out back. Didn't blow up, but the connectors were getting warmer than I like. Went to Sams Club, and paid 30 bucks for their 100-foot 'contractor grade' (whatever that means) 12-3, with a triple tap (clear, with an LED) on the downstream end. Gawd-awful yellow with a blue stripe, and it only wants to roll up one way, but what do you expect from cheap China junk? If I was still making a living with power tools, I'd pay the money for a quality cord, or make one, but for occasional household use, this will do. Are there any made-in-US cords any more? All I see in the civilian stores any more is the China stuff.

aem sends....

[CJT]

Is ANYTHING made in the US any more?

[Barry]

Thanks to all for the tips. I'm going to install a new plug and secure the wires underneath the screws, not the push in connectors.