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Discuss Using a proving unit to check for dead before removing this contactor. What do I probe on to ? Can someone please describe the tests i.e L1 -Earth. in the UK Electrical Forum area at ElectriciansForums.net
Your profile shows you are a trainee if you are unsure of safe isolation procedures someone should be helping you.
As above, proving unit at the top (in pic below), voltage indicator/dead tester at the bottom.
You are presumably using a tester, and not a proving unit, to measure with
![[ElectriciansForums.net] Using a proving unit to check for dead before removing this contactor. What do I probe on to ? Can someone please describe the tests i.e L1 -Earth.](https://electricians.s3.eu-west-1.amazonaws.com/data/attachments/77/77762-fb355caac9a5a3ef016ef9244637e2e3.jpg "[ElectriciansForums.net] Using a proving unit to check for dead before removing this contactor. What do I probe on to ? Can someone please describe the tests i.e L1 -Earth.")
Terminology, particularly in regard to equipment and units of measurement, is important in this business!
You are presumably using a tester, and not a proving unit, to measure with
Terminology, particularly in regard to equipment and units of measurement, is important in this business!
Thanks Avo , Would be using proving unit as it is only to check no power is at the contactor before replacing it. I was just curious if the checks would be across L1-T1 and then L1-Earth as there is no neutral and it's only single phase. Also prob check there is no 24v on A1 . ? Is that correct? ThanksAs above, proving unit at the top (in pic below), voltage indicator/dead tester at the bottom.
You are presumably using a tester, and not a proving unit, to measure with
View attachment 117854
Terminology, particularly in regard to equipment and units of measurement, is important in this business!
Sorry I'm not being clear - I'm concerned with your use of the term "proving unit" in your question!
You can't use a 'proving unit' to test with!
For a start it doesn't have any probes. Its sole purpose is as a voltage source to check that a tester (another instrument) actually works.
I imagine you intend to use a tester (NOT a "proving unit') with probes (something like my lower picture) to do the checking with, first applying the probes to the proving unit to ensure the tester is working, and then in your case between a ground (which you know is actually a solid connected ground), and the terminal you want to check is dead or alive.
L1 and T1 are the connections to one 'switch' of the contactor. If the contactor is open, there may be incoming power, but not outgoing. It wouldn't be my choice to measure between them if you want to check for power.
Your other suggestion seemed more appropriate.
The principle is surely to check there's no hazardous voltage on any wires you might come in contact with. The whole thing needs to be dead!
PS I think A1 would only be 12V DC when the system is powered - a mains voltage tester might not indicate that low a voltage.
You can't use a 'proving unit' to test with!
For a start it doesn't have any probes. Its sole purpose is as a voltage source to check that a tester (another instrument) actually works.
I imagine you intend to use a tester (NOT a "proving unit') with probes (something like my lower picture) to do the checking with, first applying the probes to the proving unit to ensure the tester is working, and then in your case between a ground (which you know is actually a solid connected ground), and the terminal you want to check is dead or alive.
L1 and T1 are the connections to one 'switch' of the contactor. If the contactor is open, there may be incoming power, but not outgoing. It wouldn't be my choice to measure between them if you want to check for power.
Your other suggestion seemed more appropriate.
The principle is surely to check there's no hazardous voltage on any wires you might come in contact with. The whole thing needs to be dead!
PS I think A1 would only be 12V DC when the system is powered - a mains voltage tester might not indicate that low a voltage.
Last edited:
A “proving unit” simply proves your tester is working….
The procedure is, test the tester on the proving unit first (should light up) then test the wires…
Finally test on the proving unit again.
It basically proves your tester has worked throughout the sequence.
The procedure is, test the tester on the proving unit first (should light up) then test the wires…
Finally test on the proving unit again.
It basically proves your tester has worked throughout the sequence.
Reply to Using a proving unit to check for dead before removing this contactor. What do I probe on to ? Can someone please describe the tests i.e L1 -Earth. in the UK Electrical Forum area at ElectriciansForums.net
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