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Why does my MOT have a wire from the HV coil connected to the casing? Answered


I'm busy with making a spot welder from a MOT (microwave oven transformer), but I'm not really sure why and how to ground the MOT.
In the picture you can see that a wire from the high voltage coil is connected to the casing which I find to be Really odd.

That wire is not really a problem since I'm going to remove the secondary windings, but I'm just interested in an answer to that.

Another question is, is it necessary (for performance) to have the MOT grounded?
or is it Only for safety that the casing needs to be grounded?

(no matter what the answer is, I'm still going to ground it, so it's not necessary to have safety discussions here)

thanks in advance,




Best Answer 6 years ago

As you can see the frame core ground is connected to the magnetron tube
anode which is also grounded.
Ground is positive for the magnetron. . . . . . . .  A


As per Conker-X comments.

"Shall I post?" always is.

I meant on the existing core. I'm not sure its a ground shield.

How many secondary wires have you got ?

(Have a search for Kiteman's Law)

That will be a ground connection - should something go wrong and the coil shorts out, the other end of that wire is probably uninsulated and wrapped around the insulated wires.

Come the short, the highlighted wire grounds the current to the casing, which is (was) connected to the metal casing of the microwave, which is, in turn, also grounded.

Basically, if the coil goes pop, you don't.

(I hope you're taking photos of your Make, ready to post a step-by-step instructable?)