After removing the old light from my kitchen in preparation for fittiing a new light I find an embarassingly large number of wires. To be on the safe side, I check the two wires which seem to be switched live and neutral.
However although they measure 240 volts when the switch is 'ON' they measure 165 volts when the switch is at 'OFF' !!!!!!!!!!!!!!!!!!!!!!!
Does this 165 volts suggest any particular fault to anyone ?
Thanks
On Thu, 15 Jul 2004 20:14:02 +0000 (UTC), snipped-for-privacy@spamfree.co strung together this:
Depends, it's probably not actually 165V but EMF. If it were 165V the bulb would be on at halfish brightness. I'm guessing you're using a cheap DMM to measure this with.
With a 100M input impedance a very expensive DMM would give exactly the same result. What you really want is a very cheap analogue meter with 1000ohm/volt or less (or even better a 15W bulb and two lengths of wire) as a test set.
Eh? The higher the input impedance the better on a general purpose DVM. You should use an external load to stop this effect.
That's a pain in the arse, though. For the majority of work, a 100kOhm impedence on voltage ranges would be far more useful than 10Mohm. I'm surprised more DVMs don't have this as a selectable feature.
Christian.
A nice high impedance is indeed good if you are working on high impedance circuits. It's a pain in the proverbial if you are using it as a general purpose meter on low impedance circuits such as cars and mains electricity. I agree you can use an external load - but that's messy and most users don't understand it.
If all your electrical work is car/mains you will never need a high input impedance meter, it will simply give misleading readings.
More and more you'll need a DVM to check engine and ABS sensors etc on a car, and a high impedance one is *essential* for this. For normal fault finding round the lights etc a test lamp is more use.
HP ones always used to have a 'load' button.
SNIP
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