How to conduct continuity test for cable sized 250 sq. mm?

In summary, Dave suggests using a voltage source to match the voltage on the other side of the cables to identify them.f
  • #1
Good day everyone!

I would like to ask if it's ok to use a digital or analog multi-tester in testing a 15 meters, 250 cable? We are tracing buried cables from the main circuit breaker to the concrete post. We are connected to Delta X'mer, 230 V, 4 wire w/ ground System. The x'mer will not be connected to the system while testing. I've attached the schematic diagram of the proposed method of testing. I appreciate any suggestions/recommendations. Thank you very much.

  • #2
If the purpose of the continuity test is to verify which cable is which, then a VOM (digital or analog) will certainly do the job. If you have known, or suspect issues with the integrity of the cables then you should consider more robust testing methods suggested and approved by a certified engineer. 500kVA is a lot of current, and demands rigid compliance with codes and safety guidelines.

  • #3
Thanks for the reply Fish4Fun! We're conducting continuity test to verify which cable is which so that the provider of x'mer can connect the correct cable for each phase. When the provider initially connects all the 4 wires of each phase, the fuse cut-out of the x'mer tripped off. We are instructed to determine the correct groupings of the cable because all of the markings have been erased. The Electrical Engineer of the building has passed away and the blue print that left is quietly old.
  • #4
ok You have stated ALL power is disconnected!

so you don't have to extend the meter leads between the far ends of the cables.
At the top of the post end in the first group of 4 conductors strap a pair of them together
at the main panel board end look for a s/c between a pair of cables in that group
you can then use that to identify the other 2 cables of the group.
Once those 2 cables have been marked you can remove the short between the the initial 2 you shorted together and identify them individually using a short between one of them and one of the 2 marked cables.
10 minute job ... piece of cake :)

  • #5
Dave's idea seems pretty good. We did that once.

You could also try connecting the cables to a voltage source one at one side and measure the voltage on the other side. Maybe use a car battery. Two wires one to + and other to -ve terminal of battery. Measure the voltage on the other side and you'll have a match.

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