We do not know what other cables are contributing to this (very small) drop.
Indeed ...We do not know what other cables are contributing to this (very small) drop.
... you could thereby estimate the L-N impedance of the SWA (plus any other cable in the circuit, which could be the problem!) .... hence calculate an estimated length.
I think the OP understands that, but the problem is that he cannot measure the resistance 'from end to end' - since he only has one end, and the whole purpose of what he wants to do is to try to work out how far away (wherever) the other (so far undiscovered) end is!i.e. 4mm SWA copper conductors have a resistance of 4.61 milliohms per meter, so if you measure 330 milliohms of one the conductors in the swa from end to end; divide the result of 330 by 4.61 and you will get a result of 71.58 meters.
Do I take it that tracers are available that can do that (safely!) on a live cable?other options a cable tracer connected to the panel that sends a signal back down the mains that you locate with a receiver
Interesting. As you say, it sounds pretty useful. Do you get any problems from 'cross-coupling' of adjacent cables (any idea what sort of frequency it uses?)?Yes. I have one and it's invaluable. It takes a bit of getting the hang of how to use it, but once you've mastered it you can get the right circuit every time.
Interesting - it sounds quite clever!No it's quite clever how the receiver works. As you scan the row of fuses the receiver automatically desensitises it's self until the point where you only get a strong signal on the fuse supplying the circuit the transmitter is connected to. It's quite hard to explain without actually seeing it in action!
Thanks. I'll have a look when I have a moment.There's a video here from the manufacturer which might help a bit.
Theoretically I see no reason why it shouldn't be possible, the operating frequency would be nowhere near mains frequency and i'm sure the DB supplying the circuit would be a plenty big enough discontinity to provide a detectable refelction.(* the caveat is that we tend to do this on known-faulty / dead network cables - I don't know whether TDR works with live mains cables)
The best place to look is in the documentation for the site's electrical installation.however for future reference i really need to know where the power is fed from. I'm hoping we can work out the approximate length of the cable to give me some more ideas of where to look.
Do I take it that tracers are available that can do that (safely!) on a live cable?other options a cable tracer connected to the panel that sends a signal back down the mains that you locate with a receiver
Kind Regards, John
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