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Stupid voltage leak question
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nctnico:

--- Quote from: ebastler on January 13, 2024, 02:40:30 pm ---
--- Quote from: nctnico on January 13, 2024, 02:20:26 pm ---On a grounded device, all metal parts should be connected to the ground pin.

--- End quote ---

I very much doubt that. As I said a few posts above, e.g. some decorative metal panels glued onto the plastic enclosure might well be unconnected to anything.

--- End quote ---
That is semantics. Ofcourse this is about metal parts which are a structural part of the appliance which are close to mains voltages and where double isolation can't be guaranteed. Should go without saying. Either way, if touching an appliance gives you a tingling sensation, it is time to unplug it and have it checked / replaced.
Zero999:

--- Quote from: soldar on January 13, 2024, 04:54:18 pm ---
--- Quote from: Zero999 on January 13, 2024, 02:30:03 pm ---The reason why I doubt it's parasitic capacitance is because I can touch one side of a toroidal 1kVA transformer with one hand and earth with another and don't feel a thing and such a transformer will have far greater parasitic capacitance than a coffee maker. Mechanical vibration is a possibility, but doubt it would have raised the same level of alarm, because it would be audible i.e. the pump running.

I prefer to err on the side of caution, especially given the wording of the original post indicates it was written by a beginner..
--- End quote ---
Many years ago the steel kitchen sink was giving me the tingling.  The sink was electrically isolated because it had PVC drain. After some confusion I determined the sink was touching some aluminum foil which, in turn, was touching a toaster oven. The all-metal toaster oven had two heating elements which were metal tubes with, I assume, resistive wires inside, isolated from the outside metal tube which was held in place and electrically connected to the metal structure of the oven. Measuring resistance between the internal heating element and the external metal tube the reading is infinite resistance. But there was enough capacitance to give that tingling. The oven was supposed to be connected to earth and that would solve the problem but my apartment at that time did not have protective earth wire in the supply. This was long time ago.  This was a 6th floor apartment and the building did not have earth wiring.

I bought some heat resistant flexible tubing and put it between the metal tube and the metal clamps which hold it in place and that resolved the problem.

I think it might be asbestos but at that time asbestos was not yet dangerous.  I still have and use this toaster oven but now it is grounded.

Just an example if capacitive leak. With the oven grounded there is no problem but with the metal housing floating it does give the tingles.

--- End quote ---
I doubt it had anything do to with the capacitance. There are other reasons why the toaster leaked whilst on the drainer, yet your meter measured open circuit, such as moisture ingress into the oven, or it not being purely resistive, i.e. the resistance of some materials drops, with increasing voltage and the meter uses a much lower test voltage than the mains.



--- Quote from: nctnico on January 13, 2024, 05:02:08 pm ---
--- Quote from: ebastler on January 13, 2024, 02:40:30 pm ---
--- Quote from: nctnico on January 13, 2024, 02:20:26 pm ---On a grounded device, all metal parts should be connected to the ground pin.

--- End quote ---

I very much doubt that. As I said a few posts above, e.g. some decorative metal panels glued onto the plastic enclosure might well be unconnected to anything.

--- End quote ---
That is semantics. Ofcourse this is about metal parts which are a structural part of the appliance which are close to mains voltages and where double isolation can't be guaranteed. Should go without saying. Either way, if touching an appliance gives you a tingling sensation, it is time to unplug it and have it checked / replaced.

--- End quote ---
I agree. The internal connections should not leak to external metalwork like that. It's a sign something is wrong.
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