Testing for absence of voltage on MCHL cable

[Pete27696]

We are getting ready to start a demolition project in a mine, that we have to demo out cables with voltages ranging from 4160 to 120V. The drawings are sketchy to non-existent. Is there a tool that we can run over the MCHL cables that could tell us if the cable is de-energized and safe to cut. There is no drawings that show what cables are in what trays and this will just be weeks and weeks of tracing cables out. Does anyone have any ideas for tools or procedures we can use prior to cutting into the trays and cables to verify a safe working condition. Thanks

 

[Jraef]

Hmmm... something I would stake my LIFE on? No.

There are these for MV cables, which will only be useful if NONE of the cables are energized:
http://www.davis.com/Product/HD_Ele...frU_NWsWf8aRVlS7_A6g01Mm6ICgfbNUaAqLXEALw_wcB
But they can't be used for anything under 2400V L-G and if there is a bundle of cables, it will not tell you WHICH one has a field around it. If it were me, I would ONLY start at one end and remove it, then use voltage meters to find the other end and remove it, then take out the KNOWN cable in verifiable chunks, even if it boils down to line of sight, no matter how long it took.

 

[busman]

We are getting ready to start a demolition project in a mine, that we have to demo out cables with voltages ranging from 4160 to 120V. The drawings are sketchy to non-existent. Is there a tool that we can run over the MCHL cables that could tell us if the cable is de-energized and safe to cut. There is no drawings that show what cables are in what trays and this will just be weeks and weeks of tracing cables out. Does anyone have any ideas for tools or procedures we can use prior to cutting into the trays and cables to verify a safe working condition. Thanks

Standard procedure for MV cables is to spike them remotely.

http://www.mitchellinstrument.com/h...aluminum-c-clamp-and-6ft-of-40-awg-cable.html

Mark

 

[jerryalan]

Hmmm... something I would stake my LIFE on? No.

start at one end and remove it, then use voltage meters to find the other end and remove it, then take out the KNOWN cable in verifiable chunks, even if it boils down to line of sight, no matter how long it took.

start at one end, hand over hand remove the wire from the cable tray before you cut out that section and proceed, hand over hand until you reach the other end.
or shut down and lock out all supply and whack away.

 

[AKElectrician]

We are getting ready to start a demolition project in a mine, that we have to demo out cables with voltages ranging from 4160 to 120V. The drawings are sketchy to non-existent. Is there a tool that we can run over the MCHL cables that could tell us if the cable is de-energized and safe to cut. There is no drawings that show what cables are in what trays and this will just be weeks and weeks of tracing cables out. Does anyone have any ideas for tools or procedures we can use prior to cutting into the trays and cables to verify a safe working condition. Thanks

Nope, and if there was a tool that did that, who says you don't cut a de energized motor feeder cable that becomes energized later on after the starter engages.

 

[busman]

Nope, and if there was a tool that did that, who says you don't cut a de energized motor feeder cable that becomes energized later on after the starter engages.

If you've spiked the cable properly with an appropriate ground then the OCPD opens.

Mark

 

[AKElectrician]

If you've spiked the cable properly with an appropriate ground then the OCPD opens.

Mark

The OP was looking for short cuts, and MCHL would need stripped to properly access the wires to put a "spike". Why would they do more if they are looking for short cuts?

 

[petersonra]

We are getting ready to start a demolition project in a mine, that we have to demo out cables with voltages ranging from 4160 to 120V. The drawings are sketchy to non-existent. Is there a tool that we can run over the MCHL cables that could tell us if the cable is de-energized and safe to cut. There is no drawings that show what cables are in what trays and this will just be weeks and weeks of tracing cables out. Does anyone have any ideas for tools or procedures we can use prior to cutting into the trays and cables to verify a safe working condition. Thanks

Personally, I would not want to be taking any shortcuts. It is too easy to fool one's self into believing one can't be hurt because of one's genius at finding some way to move things along faster.

Even if there were perfect drawings how would that change anything? Do it right and go home safe.