Never seen them before, look good bit of kit, I have really got to move with the times, good job I don't work much now.
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Tips and tricks?
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Never seen them before, look good bit of kit, I have really got to move with the times, good job I don't work much now.
Clamp meters (for measuring current) are not only useful for fault finding and diagnostics. They are also useful for locating circuits in messy boards, particularly neutrals.
For instance, following an addition or alteration to a circuit, you will want to do an IR test, which obviously requires disconnection of the neutral and line conductors. The line is usually easy, but finding the correct neutral can often be problemmatic, especially if wired in singles, and you're presented with summat like this:
Yep, there's a neutral bar in there somewhere. No, I'm not allowed to power down half the installation to disconnect the right hand breakers to find it.
Here's how to do it: before you start your addition or alteration, the circuit will presumably be energised. Clamp the line conductor of that circuit, make a note of the reading (say, 2.68A, for lights) - will need a load on, obviously. Now clamp individual neutral cables one at a time, starting with the ones that are the same CSA as the line conductor.
If you get one that reads about the same, then (assuming you have permission to isolate), isolate that circuit. Does the reading go to zero? If yes, you've probably got the right circuit - although there's still a very small possibility that you've got the wrong circuit, and the load (on another circuit that you've got your clamp meter around) happened to go off at the time you flicked the switch on your intended circuit. So switch it back on again. Does the reading go back up again? Cool. Mark up that cable. Now do safe isolation and do your work.
I'm sure you all know this, but to be absolutely clear: this method (clamp meter) does NOT prove isolation, it only indicates the likely cable for that circuit. Use the correct instrument(s) to prove dead and follow safe working procedures.
For instance, following an addition or alteration to a circuit, you will want to do an IR test, which obviously requires disconnection of the neutral and line conductors. The line is usually easy, but finding the correct neutral can often be problemmatic, especially if wired in singles, and you're presented with summat like this:
Yep, there's a neutral bar in there somewhere. No, I'm not allowed to power down half the installation to disconnect the right hand breakers to find it.
Here's how to do it: before you start your addition or alteration, the circuit will presumably be energised. Clamp the line conductor of that circuit, make a note of the reading (say, 2.68A, for lights) - will need a load on, obviously. Now clamp individual neutral cables one at a time, starting with the ones that are the same CSA as the line conductor.
If you get one that reads about the same, then (assuming you have permission to isolate), isolate that circuit. Does the reading go to zero? If yes, you've probably got the right circuit - although there's still a very small possibility that you've got the wrong circuit, and the load (on another circuit that you've got your clamp meter around) happened to go off at the time you flicked the switch on your intended circuit. So switch it back on again. Does the reading go back up again? Cool. Mark up that cable. Now do safe isolation and do your work.
I'm sure you all know this, but to be absolutely clear: this method (clamp meter) does NOT prove isolation, it only indicates the likely cable for that circuit. Use the correct instrument(s) to prove dead and follow safe working procedures.
D
davesparks
FFS, why have I never thought of this one before!
old dogs can learn new tricks
Thanks both, that's made me smile.
Cheers for posting. You never know what you're capable of until you're put under a bit of pressure. "Necessity is the mother of invention."
H
hightower
My dad was suffering with nuisance tripping but so infrequent that it was hard to track, so I made an extension lead about 1 foot long and took about 3 inches of the external sheathing off in the middle to expose the 3 cores of the flex (still insulated). Allowed me to plug in appliances one by one and check the current running through the CPC. Turned out it was a faulty floor lamp that was trickling to earth.
The lead is heavily marked "FOR USE WITH CLAMP METER ONLY" and tucked away in a box, so not like I will use it to plug in the lawn mower.
The lead is heavily marked "FOR USE WITH CLAMP METER ONLY" and tucked away in a box, so not like I will use it to plug in the lawn mower.
High Tower I like the way you resolved the problem (respect) but...... if you have full access to the house, clamp the live tail and shut down the board. Turn each MCB on as needed, then turn the appliances on. Faster way to find this type of fault without doing any cabling work 
Clamp meters are a very useful tool when used correctly.
Clamp meters are a very useful tool when used correctly.
H
hightower
High Tower I like the way you resolved the problem (respect) but...... if you have full access to the house, clamp the live tail and shut down the board. Turn each MCB on as needed, then turn the appliances on. Faster way to find this type of fault without doing any cabling work
Clamp meters are a very useful tool when used correctly.
Do you mean clamp the earth?
I hate my electricity going off as it means I have to set the digital clocks again (who uses a 9v battery for backup? not me) - just used this method to try and save on disruption.
Sorry HT I did not read your post correctly. Yes what you have done is correct, well done, good way of finding a fault on an appliance.
The method I posted above works for circuits when clamping L-N-E at a time and plugging things in whilst the house is shut down. Saves time and effort (and frustration). Well done, I like the way you think.
The method I posted above works for circuits when clamping L-N-E at a time and plugging things in whilst the house is shut down. Saves time and effort (and frustration). Well done, I like the way you think.
With an earth leakage clamp just clamp both line and Neutral tails at the same time. The reading on the meter is the imbalance between the two, IE, the earth leakage current.
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H
hightower
Yep, I understand this, however it was easier (as in disruption) in this instance to go around plugging in my mocked up extension lead one by one
Cool, just thought i would point it out incase. You got your tripping sorted without any disruption so good thinking there. :rockon2:
Hi everyone,
If...
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