[AT] Check the grounds, check the grounds, check the grounds

Dean Vinson dean at vinsonfarm.net
Sun Aug 1 19:01:47 PDT 2010


Mike, you're right about that good rule.  My problem was just bone-headed
lack of awareness... it didn't seem like I was working on anything serious,
just unscrewing a nut and replacing some tape for Pete's sake, didn't even
occur to me to disconnect the battery.  Sure got my attention when that
wrench closed the circuit, though.

Dean


-----Original Message-----
From: at-bounces at lists.antique-tractor.com
[mailto:at-bounces at lists.antique-tractor.com] On Behalf Of Mike Sloane
Sent: Sunday, August 01, 2010 1:13 PM
To: Antique tractor email discussion group
Subject: Re: [AT] Check the grounds, check the grounds, check the grounds

As a general rule of thumb, any time you are doing on "hot" electrical 
equipment - ammeter, light switch, generator/regulator, solenoid, etc., 
you should disconnect the ground strap/cable from the battery and push 
it off to one side. Most folks, like you and I, learn to do this the 
hard way.

It is a LOT more important to remove any jewelry, such as rings, metal 
watch bands, ID bracelets, and neck chains. I knew a couple of mechanics 
who had only 4 fingers on their left hand because they refused to remove 
their wedding rings at work. Nowadays, a lot of mechanics wear gloves, 
but I wouldn't depend on something like that - better to remove the 
metal stuff and be safe.

Mike

On 8/1/2010 11:10 AM, Dean Vinson wrote:
> Well, I wasn't actually worried about this, but I've confirmed that the
> cotter pin that holds the painted starter control rod onto the painted
> starter switch lever on top of the starter motor on my Super M has a good
> ground.  Seemingly all 12 volts and 1000 amps worth.
>
> One of the ammeter leads is connected to the electrical post on the
starter
> motor, right where the main battery cable is connected.  I noticed that
> there was some black electrical tape on the ammeter lead that was coming
> loose where the wire is crimped into the ring terminal, so I decided to
take
> the wire off and replace the tape.  (This new Super M doesn't need much,
so
> I have to look hard for something to fix on it).  While loosening the 5/8"
> nut that holds the ammeter lead and the main battery cable onto that
> electrical post, I turned the wrench far enough to bring it into contact
> with the end of that cotter pin, which hangs there about an inch away.
> *BIG* spark.  Plus my wrench now has a little arc-welded divot on one
edge.
> Definitely made that simple task a little more exciting than I'd expected.
> And if I ever need a known good ground with which to test something else
on
> the tractor, I'll know I can trust that cotter pin.
>
> Dean Vinson
> Dayton, Ohio
> www.vinsonfarm.net




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