A cheap ANALOGUE meter will provide the most reliable readings with this sort of test.
shock from a light stand
- Thread starter Albert
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Yes, recall a university physics graduate measuring a capacitive induced voltage with an AVO 7 and then with a Fluke digital and insisting that someone was switching the power on when he used the Fluke and off when he was using the AVO. He got very confused when the Fluke was showing a voltage and some one then put the AVO leads onto the Fluke leads and the voltage dropped to zero.
He did ask the explanation and eventually become a very useful engineer.
The Fluke 1653 has an input impedance of 3.3 MOhms (on voltage measurement), whereas their voltage testers (T+ series) work out at around 20 kOhms. In fact they limit test time to 30 seconds because of this, and then require you to wait for the resistor to cool down.
Different tools for different jobs.
Different tools for different jobs.
The Fluk 1653 is protected.
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We've deviated from the OP a bit here.
The safe touch voltage for metalwork is 50V, so I find it highly unlikely a shock was received from the fitting body.
The two possibilities in my mind are either static, or one of the changing a lamp with the power on scenarios mentioned earlier.
The safe touch voltage for metalwork is 50V, so I find it highly unlikely a shock was received from the fitting body.
The two possibilities in my mind are either static, or one of the changing a lamp with the power on scenarios mentioned earlier.
I must be missing the point. That sounds like a non sequitur to me.
That would be one.
A test for polarity at the lampholder would be the other I would carry out.
A test for polarity at the lampholder would be the other I would carry out.
Polarity in the socket is ok, polarity in the lighting unit is ok. What level of voltage is considered acceptable? 11.4 V will not kill you but can some one continue using this unit?
If the voltage dis-appears with any load then it is capacitive and very un-likely to present any danger.
Just a thought, are these lamps of USA origin and have black and white wires in the flex ? If so then be aware that LIVE in USA is BLACK and neutral is white. If the plug is wired balck neutral, white live then the unit's switch if single pole will leave the lamp live when OFF,
I'm not sure you have been reading the replies in the thread to be honest. As bernardgreen explained, the 11.4V is only meaningful if backed by a low enough impedance. The air inside a house is full of voltage fields from the wiring in the house, and any large piece of metal will have a capacitance to wiring running close to it and exhibit a voltage itself.
So you don't measure such voltages with a high impedance meter like a Fluke 1653. If you have to prove safety, measure with a voltage tester which has a built-in load, or your Fluke with a parallel resistance.
But much better is to measure the insulation resistance from the L+N joined together, and the metal work of the lampstand. If this is sufficiently high, then it can't represent a hazard.
It would be worth making this measurement while flexing the stand to ensure there is not an intermittant connection, or if possible disassemble the lamp to ensure that the wiring and internal cables are sound.
So you don't measure such voltages with a high impedance meter like a Fluke 1653. If you have to prove safety, measure with a voltage tester which has a built-in load, or your Fluke with a parallel resistance.
But much better is to measure the insulation resistance from the L+N joined together, and the metal work of the lampstand. If this is sufficiently high, then it can't represent a hazard.
It would be worth making this measurement while flexing the stand to ensure there is not an intermittant connection, or if possible disassemble the lamp to ensure that the wiring and internal cables are sound.
The last thing that i wanted to add is that there are 3 metal lighting stands in this small room, and each one of them gives a different reading, two of them are identical type but different readings.
In any case I read all the replies and many thanks for them and thanks even for those who told me off.
In any case I read all the replies and many thanks for them and thanks even for those who told me off.
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