snipped-for-privacy@gmail.com was thinking very hard :
Camels and straws?
I qualified my statement with - "Normally no, a digital meter has quite a high input resistance so they draw much less than the 30mA needed to trip an RCD - but if there are other leaks to ground bring it close to
30mA, a meter might then cause a trip."Depends on the meter really, Does it have high voltage AC ranges and decent leads? Brian
Which is why its often a good idea to wire up a small wattage bulb on a cable and see if it lights blows the trip or some other strange effect like light another bulb a bit somewhere else in the house. Don't mock it has happened. Brian
It may be perfectly safe, though. One of the many problems with neon screwdrivers is that they don't put enough load on the cable to establish if the current causing the bulb to light is there in sufficient quantity; as someone else said it may be just coupled from an adjacent live and completely harmless.
Wow! More suspense than a Hitchcock film! I'd always thought of Elf & Safe Tea as a very recent phenomenon and would have expected these power engineers to be a bit sloppy about such procedures but overall that was very tight, I thought. Nice to see the old Tek 555 scopes of the day. Had one once myself. Beautifully engineered they were.
exactly, it was bullshit.
of course. FWIW the OP asked about a digital meter, not analogue, and they have way higher input impedance, so that advantage does not apply.
Let's be clear. The light fitting has been miswired but the OP doesn't know what's going on. You can place complete faith in the OP's decision of whic h wires to connect it to, and the odds are it won't go badly, but I persona lly don't share that faith. The OP does not demonstrate enough expertise to know how it could electrocute someone and how to avoid it doing so. Yes, i t most likely won't, but it can. I would thus suggest the meter rather than the lamp.
Some, and I don't mean you, just need to stop wasting other people's time.
NT
I see you've not used your brain.
Or you might be coupled to something live and the thing under test actually live. The screwdriver will tell you its safe!
snipped-for-privacy@gmail.com has brought this to us :
I see you are being offensive and for no good reason.
And it's trivially easy to be capacitively coupled to something live.
NT
Probably because of a good reason ... (that a left brainer couldn't believe). ;-)
Typical Brexiteer, making s*1t up. He said no such thing ... he actually said "Can I use my cheap digital meter" and that might mean that he is aware that some DMMs can cost hundreds and his cost £29.99 (that wouldn't make it 'cheap' by most DIY peoples standards). It may also mean that it was a £100 DMM that he bought 'cheap' from a friend or on a special (but that would be less likely from the usage and context).
Most DMM's come from China and a £3.99 job could equate to a £19.99 job bought in a UK retail outlet.
But I have done so (many times) and yet somehow I'm still here (except the DMM actually cost 99p but I did have to supply my own PP9 battery).
That said, 'of course' there is a minimum design / build spec that most who know what they are doing would consider ideal / acceptable (and ironically makes them potentially safer for novice use).
To be *formally* rated for such voltages.
Cheers, T i m
Avo Model 8 is typically 1mA on AC.
And my 1920s meter takes far more. Of course there are meters that aren't typical. Are you trolling?
Just trying to point out to you that a mechanical analogue meter takes more current measuring AC than DC. So typically not 50uA on a 250v AC range.
But if you think that trolling, carry on.
I am sure you are well aware of the spectacular holes in that bit of logic. So far I have never been hit by a car while I am crossing a road. It does not mean that it can't happen or is necessarily that rare an event.
One of the difficulties with many cheap chinesium meters is that they may claim Cat II or Cat III certification, and yet even a cursory glance inside[1] shows that to be wishful thinking.
Now chances are you will be able to measure voltages inside your CU with one of those many times and get away with it. The problem comes when you don't because there was a 1kV transient at just the wrong moment.
he further you move from a CU - out to the far reaches of a circuit or in fact into an appliance, then generally the lower the risk.
[1] Inadequate conductive path separation, lack of low to high voltage isolation, no HRC fusing, no spark gaps, no input protection MOVs etc.
it's trolling because it has no relevance to the OP's situation, who has a DMM, and no significance to a typical analogue multimeter that takes more than 50uA but way less than 1mA on ac.
So it looks like you trolled successfully.
NT
More's the pity. Why don't you stick your tongue in a 13A outlet and do us all a favour?
Had a Fluke DMM that showed 238V but circuit not working. AVO 8 showed about 215V; lowered the range and each time the voltage dropped more. Cause was RS Octel relay just touching but not making.
I've an old, bodged [1] analogue meter that meets zero standards but is good for checking where the DMM is no good.
[1]. Casually thrown together from spare parts in the electronics lab at Plessey Microsystems by, Dog help me, and electronics 'engineer'
Ages ago I bought a Maplin Gold DVM. When such things were pricey. Normally only used for electronics, so all fairly low voltage stuff. When it was a few years old, I measured mains with it. Large bang and clouds of smoke. On stripping down it had arced over on the switch tracks. My guess was copper etc dust just from wear and tear on the switch.
I now have one of those 'stick' meters sold specifically for mains testing.
Well it was you who (unfairly in my view) criticised Harry's comment suggesting that measurements on circuits can be more reliable if made with a meter / device that is capable of sinking a small amount of current in preference to a very high impedance meter.
So I see no requirement that every post in a thread need address only the OP.
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