insulating ammeter

Mon Nov 25, 2013 8:02 pm

I have a new wiring harness that I am connecting to the dash instruments. The ammeter is held to the dash by a 3-sided metal bracket. I suppose I need tape or thick paper to insulate the two screws with their nuts and wires from the bracket. Else I'll get a short, right? But won't the two screws short out by touching the edges of the holes through the bracket? And...is the screw behind the left side of the ammeter (viewed from the driver's seat) the negative?
Charles

Re: insulating ammeter

Mon Nov 25, 2013 10:27 pm

The bracket should have grommets in the two holes so the lugs from the meter slide through them and don't touch the bracket. A washer against the grommet and a nut to tighten the bracket and then add your wire and another nut. I have also seen a nylon washer with a lip that fit the hole so the lugs wouldn't touch the bracket. Do a search on ebay for ammeter and look at the brackets.

Which side is which? I just hook them up and see which way the meter moves. It's a 50/50 chance and I ALWAYS get it wrong.

Re: insulating ammeter

Tue Nov 26, 2013 9:46 pm

Thanks, Scrivet. I will look for those parts tomorrow!
Charles

Re: insulating ammeter

Tue Dec 03, 2013 9:52 am

I have cut a slit in a piece of vacuum hose to slide on the end of the bracket just in case.

Re: insulating ammeter

Tue Dec 03, 2013 10:17 am

oronc wrote:I have cut a slit in a piece of vacuum hose to slide on the end of the bracket just in case.

That will prevent it from shorting out. However, it will not prevent the bracket from shorting the 2 ammeter lugs together. If that happens, your ammeter will perpetually show zero. For the ammeter to work, the bracket must be insulated from the lugs.

Re: insulating ammeter

Tue Dec 03, 2013 10:45 am

Jim Becker wrote:However, it will not prevent the bracket from shorting the 2 ammeter lugs together. If that happens, your ammeter will perpetually show zero. For the ammeter to work, the bracket must be insulated from the lugs.
Heat shrink on the amp meter posts/lugs and plastic washers from hardware store.

Re: insulating ammeter

Tue Dec 03, 2013 5:16 pm

To test the ammeter and the way I insulated it, would it work (or harm the meter) by connecting a battery charger set on 2 amp charge, or by using a dc model train power pack?
Charles

Re: insulating ammeter

Tue Dec 03, 2013 7:25 pm

charlesellis wrote:To test the ammeter and the way I insulated it, would it work (or harm the meter) by connecting a battery charger set on 2 amp charge, or by using a dc model train power pack?
Don't know if it would work and probably not. All the model train power sources I owned were AC in, DC out.

You could test the amp meter by wiring it in series with a light bulb, such as a head lamp, or any other type of resistor.

Re: insulating ammeter

Wed Dec 04, 2013 5:24 pm

Wire it in series ---with what? tractor battery? 2 amp setting on batt charger?
Charles

Re: insulating ammeter

Wed Dec 04, 2013 6:51 pm

charlesellis wrote:Wire it in series ---with what? tractor battery? 2 amp setting on batt charger?
Charles

http://www.google.com/imgres?imgurl=htt ... CC8Q9QEwAg

Pay no attention to the title in the post, read the small lettering. So, battery charger positive lead going to amp meter, out amp meter to load (resistor - head lamp - or something to apply a load). Negative lead from battery charger to opposite terminal on load - the other head lamp terminal.