Using a 2 Pole Tester - Fluke T130

[Jupiter01]

As per advice on this forum, I have placed my order for the Fluke T130 which I eagerly await. In anticipation of this, I've been doing some reading and watching videos. I also intend to read the manual when it arrives (no RTFM comments just yet please!).

I'm also approaching this after using a non-contact fluke tester for many years and without any failures. Given their propensity to fail and the stern advice to not rely on this when working on mains, I opted to purchase the Fluke T130.

A few questions please:
- when poking just the red probe on live (without the other), I understand that this provides an indication on when Live has been detected. Out of interest, when used in this manner, is this suffering from the same limitations as the non-contact tester?
- ordinarily, I think I need to place the red probe on live and black on neutral. Correct? If yes, what happens if the neutral is disconnected upstream?
- When if ever should I test with the red on live and black on earth?

Thanks in advance.

 

[blup]

The manual is downloadable and is a basic instruction/safety sheet that assumes basic electrical knowledge.

I believe the single pole test is to identify if conductors are live not to measure voltage.

Fluke recalled my first T130 and replaced it free of charge, that aside it's reassuring to know you're using a quality product as a DIYER.

Blup

 

[securespark]

Red to line and black to earth should give a similar voltage to that across line-neutral. Unless you have a bad earth. Red to line and black to an OC neutral should give the same indication as Red to line on its own.

 

[JohnW2]

- when poking just the red probe on live (without the other), I understand that this provides an indication on when Live has been detected. Out of interest, when used in this manner, is this suffering from the same limitations as the non-contact tester?

Yes, conceptually very similar - voltage can only be detected/measured as a 'potential difference' between two points and, in both the cases you mention, one is relying on (uncertain, hence not totally reliable) capacitive coupling to earth for one of those potentials. Testing involving only one 'pole' of a tester is never safe enough to be used as a means confirming that a circuit is not live (e.g. prior to working on it). Even if the Fluke is designed so that it can be used in that mode (essentially just an up-market 'neon screwdriver'), I would personally suggest that you forget about that functionality, and only use it as a '2-pole tester'.

- ordinarily, I think I need to place the red probe on live and black on neutral. Correct? If yes, what happens if the neutral is disconnected upstream? - When if ever should I test with the red on live and black on earth?

You've more-or-less answered your own question. In order to be sure/safe, one should (at least in my opinion) always test both (L-N and L-E) - since, as you say, it's possible that there is an upstream break in the neutral, in which case we would be back to a 'one-pole test' (if the meter supported that function), not reliable enough for safety.

Kind Regards, John

 

[Jupiter01]

Thanks @JohnW2. Does Earth not suffer from the potential of an upstream break too?
Finally, in the event that L-N doesn't detect voltage but L-E does, is there a secondary test that should be performed?

I am trying to establish some best practice principles.

 

[JohnW2]

Thanks @JohnW2. Does Earth not suffer from the potential of an upstream break too?

Sure, that's possible - which is why one should (IMO) test both L-N and L-E. If there is a break in the earth, L-N should still show voltage (if the circuit is live) and if there is a break in the neutral, then L-E should show voltage.

Anticipating the next question, if one had the extremely unlikley scenario of breaks in both L and N, then neither L-E or L-N would show voltage (even if the L were 'live'). That's very unlikely to happen but, if you want to minimise the risk of failing to detect that, I suppose you should also use a 'one pole tester' on the L (albeit accepting that that is far from foolproof!).

Don't forget that if the neutral were broken, the circuit would not be 'working', so you would presumably be aware of a problem even before you started doing any testing.

Finally, in the event that L-N doesn't detect voltage but L-E does, is there a secondary test that should be performed?

If you had that situation, one would look into the reason for (and location of) the apparent break in the neutral.

Kind Regards, John

 

[flameport]

I suppose you should also use a 'one pole tester' on the L

The Flkue T130 and most similar test devices are also one pole voltage detectors.

 

[JohnW2]

The Flkue T130 and most similar test devices are also one pole voltage detectors.

Yes, that's true - not the least so that they can detect voltage even with flat batteries. However, it remains the case that in it's 'one pole' mode it is "not foolproof".

Mind you, particularly in terms of 'testing for dead', I think we're probably scraping the barrel more than a bit ... it is surely incredibly unlikely that a circuit that was supposed to be 'dead' (because one had operated some isolator/whatever) would somehow end up with a live L and broken N and E conductors

Kind Regards, John

 

[Jupiter01]

Just one further question for now please: I am aware that the Fluke T130 also does continuity testing. Are there any good examples of when you guys tend to use this in domestic situations (I can appreciate its use on circuit boards, motors, etc.)?
I thought it might help with detecting the switch wire at the ceiling but in most instances the other end of this wire (at switch) will be much further away then the length of the Fluke cable.

Interested to hear of potential uses.

 

[bernardgreen]

detecting the switch wire at the ceiling

With the power turned OFF ... At the ceiling rose ( or lamp fitting ) with the meter set for AC volts 250 connect one test lead to the one wire in the cable you believe is the switch cable, connect the other test lead to the other wire in that cable. If no voltage (*) then set meter to continuity with bleep. Go to the switch and operate it, if you can hear continuity bleep with the switch ON and not hear continuity bleep when the switch is OFF then you have found the switch cable.

(*) proof that the cable is not connected to a power source. Checking for safety is essential at all times when working on electrical installations.

 

[Jupiter01]

Thanks @bernardgreen but I have a two pole tester (Fluke T130) and not a multimeter. I think the process is different for me as I don't have the option to switch between voltage and continuity, I think...
Looking forward to your guidance as detecting the switch wire with this device would be an added bonus.

 

[bernardgreen]

The Fluke T130 Indicates a voltage any time without being "Set" to voltage ( I didn't realise that ) and also measures continuity. The instruction manual will provide information on how to measure continuity.

 

[SFK]

Jupiter,
Manual is here: http://www.free-instruction-manuals.com/pdf/pa_1424110.pdf
And Bernards method is correct, if there is no voltage it automatically goes into continuity/beep test mode. If there is a voltage then it shows the voltage.

Regarding other uses of continuity:
- Testing fuses
- Testing switches to show if working
- Testing Relays to determine which is NO or NC

FROM MANUAL:
To do a continuity test of cables, switches, relays, bulbs, or fuses:
1. Do a Voltage test to make sure the UUT is not live.
2. Connect the two test probes with the UUT. You will hear the beeper if it is on (T110/T130/T150 only) for continuity and f is on.
Note: The Tester automatically goes into the voltage measurement mode if voltage is sensed.

SFK