MTFCA Forum

Good day everyone
I got my first model T running two days ago. It’s a 1911 with an original coil box. When I turn the key from battery to mag I get a spark plug type shock. Is that normal?

No, there is a short in the switch I would think.
(congratulations on the T and welcome to the 'disease' )

No, it is not normal. You should never get an electrical shock touching a switch, not on a model T, not on anything.

A coil with an internal short from the high voltage to the spark plug to the 6 Volt input voltage with cause this to happen.

Then too, it will soon ruin your cutout and generator.

To start analysing somewhere,
Check that the wiring connecting to the switch for any broken down insulation or shorts.
Next step pull the switch apart and check all connections, contacts and insulation.
check nothing is touching the coils and earthing to the coil box (a stray wire or something)
If still shocking you, then check each coil by removing one at a time (this will show if one has the internal short Jim mentions)

Hope that gives you a starting point at least.

If I understand you correctly, you get a spark plug like shock when inserting the key in the box and turning it to mag. To get that shock the voltage from a coil would pass to the switch to the key to you . What coil box do you have - a picture of the switch would help. Is there an insulated knob on a handle as well

It's a free start

...it will soon ruin your cutout and generator.

Not if you don't have them (1911).

It is possible to get a shock from the primary side of the coils. It would occur when the circuit was switched on or broken. I don't think the handle of the switch should be "hot" at any time. With a wooden coil box, I suppose it could be and the engine would still run.

A good point Steve!

I missed that detail.

In that situation a wet coil box with the engine running can send some of that high voltage to the battery strip and develop a carbon track that will provide a path for the high voltage that is only supposed to go to the spark plug.

Not sure what coil box or switch but lots could happen in one like this - a broken contact piece

Mike Coats, are you any closer to discovering the source of the extra electricity.

The spark voltage from the coil is the only voltage that is high enough to provide you a shock.

That high secondary voltage comes out the bottom button of the coil and it is a very short trip from there to either one of your coil primary voltage sources.