I appreciate that this will of course vary from manufacturer to manufacturer, but in general terms can someone give the approximate voltage? I'm curious because I'm getting a "glow" from the outer metal casing of a SCART lead connector on several pieces of equipment.
**Depends on the screwdriver. One of mine starts at around 12 Volts. However, it is an LED, powered type. The usual, neon types start at around 65 Volts. It's not unusual to detect minute leakage currents from domestic equipment. Disconnect everything and test separately. You'll probably find it'll be the antenna. Some US equipment has a resistor from neutral to chassis. If this has been mis-wired or there is a fault elsewhere, you'll get leakage from that too.
Trevor Wilson
Add to that the fact that most switching PSUs contain Y capacitors for EMI suppression that also cause a leakage current to ground. If the equipment is ungrounded, such parts can rise in voltage to around half the supply voltage if measured into a high impedance. The leakage current is quite low however, typically under a hundred microamps..
Graham
I think you're right to be concerned. Can't tell where you are, whether you have safety grounds on the power plugs etc. I have zero experience with SCART, but pinouts.ru claims that the shield is chassis ground. The whole idea of a safety ground on the power system is to NOT have voltage on the shield/chassis.
I'd borrow an actual voltmeter and measure from the sheild to actual ground. Measuring to the power system safety ground may not help if that's the thing that's compromised. Unplug equipment until the voltage goes away. Then address the problem for a specific piece of equipment. Random remote conjecture from the web is no substitute for actual measurements.
I've had the pee, literally, shocked out of me when the safety ground in the house wiring went open. On a related note, I've also seen high leakage current when a cat decided to take a pee on the equipment.
I'm measuring about 150V AC, which in the UK is over half the supply voltage. And it doesn't appear to be just one piece of equipment. Graham (Eeyore) above has an explanation. The mains test screwdriver in question failed to light up when a car battery was being charged (about 20V DC, probably).
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