Electronic – Why are capacitors usually marked on the negative terminal, not positive

capacitormarkings

Does anyone know the reason (historical, practical, etc) that polarized capacitors usually have the negative lead marked instead of the positive lead?

I would expect markings to indicate a positive potential. Since we commonly ground the negative lead and refer to "ground" as "zero" volts in reference to the rest of a circuit, the positive side would be the "hot" or "dangerous" side, so you would think that would be the marked side, especially on high voltage caps… We color positive wires red, we indicate the "hot" side of AC circuits, etc. Emphasizing the negative lead seems backward to me.

Best Answer

Why are capacitors usually marked on the negative terminal, not positive?

Here some polarized capacitors: -

enter image description here

Now you tell me which is the dominant polarity marker?

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