Shocking key

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FULLBORE
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Shocking key

Post by FULLBORE » Sat Aug 13, 2022 7:19 am

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?

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A Whiteman
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Re: Shocking key

Post by A Whiteman » Sat Aug 13, 2022 7:34 am

No, there is a short in the switch I would think.
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Humblej
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Re: Shocking key

Post by Humblej » Sat Aug 13, 2022 10:08 am

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


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Re: Shocking key

Post by J1MGOLDEN » Sat Aug 13, 2022 5:06 pm

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.


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Re: Shocking key

Post by J1MGOLDEN » Sat Aug 13, 2022 5:07 pm

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

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Re: Shocking key

Post by A Whiteman » Sun Aug 14, 2022 2:19 am

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.
Last edited by A Whiteman on Sun Aug 14, 2022 5:32 pm, edited 1 time in total.

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Re: Shocking key

Post by TRDxB2 » Sun Aug 14, 2022 2:45 am

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
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Re: Shocking key

Post by Kaiser » Sun Aug 14, 2022 5:33 am

It's a free start :lol: :lol:
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Re: Shocking key

Post by Steve Jelf » Sun Aug 14, 2022 11:10 am

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

Not if you don't have them (1911). :)
The inevitable often happens.
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Re: Shocking key

Post by TXGOAT2 » Sun Aug 14, 2022 11:52 am

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.


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Re: Shocking key

Post by J1MGOLDEN » Sun Aug 14, 2022 12:40 pm

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.

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Re: Shocking key

Post by TRDxB2 » Sun Aug 14, 2022 12:52 pm

Not sure what coil box or switch but lots could happen in one like this - a broken contact piece
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The past is a great place and I don't want to erase it or to regret it, but I don't want to be its prisoner either.
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Re: Shocking key

Post by J1MGOLDEN » Tue Aug 16, 2022 3:31 pm

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.

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