How to measure the physical length of a circuit?
- Thread starter CarrotTop
- Start date
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As long as you know the where the very end of the circuit is, this can be done from the resistance as well, and also what size the conductors are you could equate the length from the resistance of the cables and comparing it with the OSG tables of resistance for cables.
could I use resistance many more times in one sentence, I think not ha ha
could I use resistance many more times in one sentence, I think not ha ha
I suppose you could blindfold yourself, and grope your way from one end to another with a tape measure.....
But seriously - think about what you're asking:
"Does anybody out there know how you can measure the actual length of a domestic light / power circuit without physically looking?"
How could there be?
But seriously - think about what you're asking:
"Does anybody out there know how you can measure the actual length of a domestic light / power circuit without physically looking?"
How could there be?
He wants to measure the actual length, not the resistance. The last time I looked lengths were measured in units such as mm, inches, yards etc, not ohms.
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but you can equate the length from the resistance as the OSG gives you resistance readings per meter.
little bit of sums and you have your length
)
little bit of sums and you have your length
)
But that's not what he asked.
That's measuring another property, and using that to estimate the length.
He asked how to measure the length, not estimate or calculate it.
That's measuring another property, and using that to estimate the length.
He asked how to measure the length, not estimate or calculate it.
Measuring length by measuring the resistance per metre seems like a possible idea, but would it work it the ring main for instance has been previously extended so that it now looks like a figure of eight? Does that make sense?
All I want to try an do if see if an existing ring main is within limits. I realise I cannot actually measure it but a way to estimate is what I am looking for. Pulling out the entire ring main is not really a viable option!!!
Calculating the approximate length would be....
No.
Well - that's progress...
The usual tests for continuity will get you the figures you need.
Indeed not...
S
saxondale
you can get a tester that`ll tell you ( to the nearest meter?) but I dont know what there called or where from LOL
Not particulaly relevant to the OP, but:
Its called a TDR ; best way to visualise it is like sonar, a signal is sent from one end of the cable, and it'll propogate along the cable at a speed that varies a little with the type of cable, for a cable with anything but a matching termination resister* though (open end or short), reflections of the signal will bounce back in the other direction, if you know the speed of propogation in the cable type and know how long the signal took, then you can work out the length to an open circuit or fault... I don't fully understand how it all works, but thats the laymans view
*remember those green terminator things you used to find on the ends of 10base2 networks?
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