Cell Phone Charger trips GFI

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Senior Member
Ann Arbor, Michigan
130508-10124 EDT

The GFCI unlatch coil is energized by a small SCR. For the GFCI to trip something has to trigger the SCR into conduction.

There are two ways.

1. A very high value of dv/dt to the anode can cause a trigger, very unlikely from a cellphone charger.

2. A relatively small short energy pulse to the gate, the normal and intended way to trigger an SCR.

If the circuit layout for the SCR gate is poorly designed, then capacitive coupling to the gate can exist that would effectively bypass any filtering in the trip control circuit.

Somewhat poor layout exists in the Leviton GFCI, but it is still very hard to trip the Leviton with line transients. Their gate lead is about 1" long. If a filter capacitor was adjacent to the gate, and a 1000 ohm resistor was tightly positioned relative to the gate and capacitor, then I do not believe that any of the high transient voltage signals I applied to the Leviton would trip it.

I suspect the problem relates to the gate circuit. Anode triggering is unlikely from a cellphone charger. Try a different brand of GFCI.

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