smoke at connection to extension????

A cable too small for the distance the juice is being carried. Trying to run 12 amps on a 60 foot 12 gauge cord is... How to word this politely... Hmmm... There is no way, so I'll be blunt: STUPID. Resistive losses in the cord at that length and amperage should, by all rights, cause your cord (and/or mower) to practically burst into flames on you within minutes, if not seconds, of turning it on. That you've managed this long is a small miracle in and of itself.

Get a heftier cable. Personally, for what you're doing, I wouldn't try to use anything with conductors smaller than about 8-10 gauge, and wouldn't hesitate to go even larger if the option were available.

You just got the best advice you're likely to find.

--
Don Bruder - dakidd@sonic.net - New Email policy in effect as of Feb. 21, 2004.
Short form: I'm trashing EVERY E-mail that doesn't contain a password in the
subject unless it comes from a "whitelisted" (pre-approved by me) address.
See  for full details.

I have used a 16 gauge cable on my older mower. It was recommended to use a 14 gauge cable with this amp mower. It works fine for my electric snow blower. My neighbor uses the smaller 16 gauge cable too.

This sounds like overkill according to the recommendations in the mower's manual. The bigger cables would be like hauling a garden hose around.

Thanks for your rsponse, I'm just confused now. It worked fine for six years. And it seemed to be what was apprpriate. Thanks

--Paul

Wow... what a crock!!! The first answer to the question was uneducated, and not what the OP needs to hear. The NEC says that the maximum voltage drop from the source to the last load on the circuit be 3% or less. A 60 ft, 16 AWG extension cord will drop 7 volts when passing 12 Amps, or a 5.8% voltage drop at 120V. A heavier guage extension cord is definitely in order, but 8-10 AWG is overkill, and the last poster suggested. A 60 ft, 14 AWG extension will drop 4.4V at 12 Amps, or a 3.7% drop. A 60 ft, 12 AWG extension will drop 2.8V at 12 Amps, or a 2.3% drop, which is within the NEC guidelines. The larger the wire, the less voltage will be dropped in the wire, and more will be available to run the load (the mower). If the voltage at your receptacle is 120V or more, and if the mower can run well at 115V, then a 14 AWG extension will work, provided you don't use it for extended periods and allow it to get very hot. Mowing a lawn might be pushing it a bit too much for safety. I would recommend buying a 12 AWG extension cord for the mower, and avoid the dangers. Back to the OP original question, it's quite possible that the receptacle on the end of the extension wasn't tight, and caused a high-resistance connection, which overheated the receptacle, causing its demise.

Cheers!!!

--
Dave M
MasonDG44 at comcast dot net  (Just subsitute the appropriate characters in 
the address)

Never take a laxative and a sleeping pill at the same time!!

Replace the Male connector from the Mower. The connection between the mower cable and the male pins (most likely a crimped connection ) has cooked and now presents a significant IxR drop, plain English, gets Damned Hot, Less likely it could be the Female Connector on the Extension Cord. Its' warm and greasy because its cooler than the Male pin which was hot enough to char the melting plastic break-down products.

Is it overheating and triggering the internal Circuit Breaker because of low line voltage ? Brown-out ! motor spinning to slowly because of excessive voltage drop somewhere in the Power Cord/Extension Cord.

12 Gage is fine for the Lenght and Load described, 14 gage is marginal.

Yukio YANO

--
That's ridiculous. 

#12AWG has a resistance of about 1.6 ohms per thousand feet, so 120
feet of it has a resistance of about 0.2 ohms.  That means that with
12 amps running through it it'll be dissipating about 30 watts, or
about half a watt per foot of cord.  That's hardly likely to do much
more than than make it barely perceptibly warm.

--- If the breaker keeps blowing it sounds to me like youve got either a faulty breaker, a motor problem, or you're mowing too aggressively and overloading the motor! I suggest that the first thing you do is check the motor current while you're mowing in order to rule out the aggressive mowing, and then if you still have too much current being drawn, it may be time for a new motor.

I suspect that what happened at the connection between the cords is that a high resistance developed there, for some reason, and it overheated, making the condition worse, causing it to heat up even more...

What I'd do there would be to cut off the plug and socket and replace them with a new heavy-duty 20 or 30 amp set. you could even get Twist-Locks so you wouldn't have to worry about the lines unplugging or having to tie the cords in a knot to keep that from happening.

-- John Fields Professional Circuit Designer

Top posting for OP. John Fields gave you the correct info. The twist lock male and female are the way to go. Warren

Top posting for OP. John Fields gave to the correct solution. The twist lock is the way to go. I use a 16 gauge 50 foot on my mower, no problem. Warren

Great info and advice. The connection had always been loose. I had to tie the ends together so the motion would not shake them apart. I have cleaned the prongs and will try the following:

-test it again as is with the connection as tight as i can make it.

-replace connectors with new, tighter, heavy-duty ones.

-replace extension with 12ga Thanks for all your contributions (ain't this 'net thing great?)

--Paul (OP)

Yes I agree and have had this exact situation happen with a resistive connection on my electric mower except it was a little more obvious because the male end just melted into a gooey blob. BTW do you use a GFCI to feed your extension cord? I have a little pigtail that I rigged to a GFCI in a box that I use to power my mower from all the antique circuits in this building. It has popped a few times over the years due to little nicks in the cord.

It sure is. Richard

Richard The outside power boxes on my home are on a GFCI circuit. So that is not a problem. And my mower has a circuit breaker built in.

To all contributors: The problem was solved by using a short extension of 12ga wire with a connector that fits in the mowers plug tightly. The other end fits to my 60' extension also tightly. Now the mower works without smoke! (I also sharpened the blades, a good thing for any mower but especially an electric) Again thanks to all.

--Paul

Paul, As Yukio pointed out that internal breaker in the motor was probably cutting out because the motor was getting too hot due to to the lowered voltage. Note that this is a thermal breaker and has been required in motors for some time I think for fire protection. I've seen them all the time even in induction types. Richard

Hey Paul,

2 things come to mind: 1) Bad connection...like a loose connection. This may cause overheating at the connection itself usually possibly melt the wire or terminal. 2) A motor winding has burnt.

Hope this helps