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Electrical noise created by 3ph machine

Steve Phillips

Hello all

Life long sparky... semi-retired now, but working at a local workshop

The company had a local (rather shoddy) electrical company come in and re-supply a 3ph, 35A per phase painting/spray machine.    It was fed before and created flickering in the office fluorescent lights.

But, it still does it.  The fluorescent lights in the offices on the mezzanine nearby flicker when the machine pulls a high load.

It's fed from a sub DB that has a 125A, 25mm 3ph SWA supply (This run is considerable from the incomer - probably somewhere like 70M+.   

Machine MCB is 32A

They used 6mm 5 core SY cable (I would have gone 10mm) over a 25M run.  But they laid it on top of (not in) a 4" galv trunking with T&E inside.  Entirely possible the lighting feeds run within this trunking.

I may unstitch the cable and move it away from the trunking, but I am not entirely convinced that is the issue.

Any ideas on what to try?  

Personally, I would rewire the machine directly back to the incoming mains cupboard, but that is no easy task.

Parents
  • 0

    Thank you.

    The sheath of the SY (for what it's worth), is connected to earth at the supply end (the outlet to the machine is a plastic 5 pin industrial connector).

    Local earth rod near the machine?  I am dubious that the earth at the DB is all that great, due the distance.

    I think I will start by moving the cable 1m away from the rest of the cabling.

Reply
  • 0

    Thank you.

    The sheath of the SY (for what it's worth), is connected to earth at the supply end (the outlet to the machine is a plastic 5 pin industrial connector).

    Local earth rod near the machine?  I am dubious that the earth at the DB is all that great, due the distance.

    I think I will start by moving the cable 1m away from the rest of the cabling.

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