When I touch the probes together, everything lights up and the unit beeps. This includes the voltage display and the red lights across the side indicating the voltage detected. I was advised to rely on the lit up voltage display as opposed to the screen display.
2 Pole Tester Usage
- Thread starter Jupiter01
- Start date
When I touch the probes together, everything lights up and the unit beeps. This includes the voltage display and the red lights across the side indicating the voltage detected. I was advised to rely on the lit up voltage display as opposed to the screen display.
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What does the display show when you touch the probes together?
Switch off power for continuity tests on circuits.
Switch off power for continuity tests on circuits.
Double pole switches - Main Switch, RCCB, RCBO etc will separate the N and E.
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A correction to what I stated earlier: if I briefly touch the probes together I get a beep and the following (circled in red) lights up:
If I leave the probes in contact for around 5 seconds, everything lights up and beeps. I get a reading of 1.8888.
That looks like a lamp test feature that proves all the indicator lamps and all the segments in the numerical display are working.
.
RCBOs are usually single-pole, aren't they?
However, your suggestion was ...
... and I'm finding that hard to understand. With the N 'isolated' (by a DP switch), one would (in the absence of an N-E fault) surely not see 'continuity' (low resistance) between the N and anything, would one?
Or am I missing something?
Kind Regards, John
Some aren't, but yes.
I should have added another qualifier but can't explain everything.
Yes, but I added
"Double pole switches - Main Switch, RCCB, RCBO etc will separate the N and E."
intending to mean don't do that.
Just switch off the MCB or pull the fuse.
Sometimes it is difficult to explain everything about the obvious.
Ah - I took it to mean "do do that" - my apologies
That's fair enough with TN-C-S.
However, with TN-S it's very likely that there would be at least a very small (AC) potential difference between N and E, which presumably would/could completely mess up (in an unpredictable fashion) attempts to measure resistance with a meter - and with TT it wouldn't surprise me if a resistance meter (using very low voltage DC) failed to find much in the way of continuity at all (and certainly not the "ohm or so" you suggested).
We don't know what earthing system the OP says, but it sounds as if the measurement would only be helpful if it were TN-C-S (and that no DP devices had been 'switched off').
Kind Regards, John
The danger is always in assumptions- (the other danger lurks when you believe what people say they have done or what has happened without any knowledge of their level of competence or experience).
Thus it is unwise to assume that just because you can see an earth in a backbox it will always be correctly connected at the other end of the cable.
The much maligned voltsticks and neon testers must not be relied on to prove dead but can be handy for first line fault finding (if a known good light isn't working but voltstick lights up its good odds you have a neutral fault).
Thus it is unwise to assume that just because you can see an earth in a backbox it will always be correctly connected at the other end of the cable.
The much maligned voltsticks and neon testers must not be relied on to prove dead but can be handy for first line fault finding (if a known good light isn't working but voltstick lights up its good odds you have a neutral fault).
Very true, and I suspect that many/most of those who do the maligning (certainly including myself) actually do use them (for appropriate purposes) more than they would probably want to admit! However, that requires a user who fully understands the potential limitations, hence 'risks' - and that probably is not the case for anyone who 'needs to ask questions'.
Safety-wise, there isn't really an issue if the neon does light up - the only 'risk' then is that one is being mislead by some 'stray pick up'. The true dangers all arise when it does not light, and no-one who 'understands' would read very much into that.
Kind Regards, John
I always use my red probe on live and black on N/E as part of the two tests. Additionally, I also test across N and E now, as per suggestion above.
In any of these tests, does it matter which coloured probe I use on which terminal?
In any of these tests, does it matter which coloured probe I use on which terminal?
No - with AC it makes no difference.
However, it's probably best that you stick to the convention you mention since it might serve to remind your brain that when measuring DC voltages it does matter (red=positive and black=negative, assuming they are plugged into the correct sockets!).
Kind Regards, John
aha...I think that's what my Fluke T130 does. If I see -ve volts with DC, I will use that as a prompt to reverse the probes.
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