Quick question for the Sparks re CPC

[MattH]

I am installing an 32A Isolator - DOL - 32A Socket to run a vacuum pump.

The singles are installed in a 4" Galv trunk which is above a machine platform. I will drop down from the trunking via 25mm conduit into the Isolator and then into the DOL but then back up the conduit into the trucking and the drop out of the trunking again with 25mm to a socket where the pump will plug in.
This is so I can keep the pump up on the platform but switch it with the DOL from below next to the CNC it supplies.

Question is do I need to run the CPC down into the isolator and DOL and then back up or can I just run the CPC direct to the Socket thereby keeping two cables out of the 25mm conduit that runs to the DOL?

The Isolator and DOL are both double insulated devices but they do both provide an earth stud inside.

 

[Dee J]

Any basis of logic would suggest that no cpc is needed... But BS7671 (the regs) 411.3.1.1 states that a cpc shall be run to and terminated at each point in wiring and at each accessory. Can't find any exemption for your situation.

 

[MattH]

Any basis of logic would suggest that no cpc is needed... But BS7671 (the regs) 411.3.1.1 states that a cpc shall be run to and terminated at each point in wiring and at each accessory. Can't find any exemption for your situation.

Indeed, hence the question.

Seems stupid to run a CPC down into the DOL only to terminate it on a stud and then run another off that stud back out of the DOL.

I will err on the side of correct though and run the CPC through the switch gear.

Thanks for the reply Dee J.

 

[sparkysy]

Fair play @MattH!! I would run a cpc because of future alterations and cos you should, say for instance the dol is changed for a metal enclosed one in the future. There really should be a cpc at every accessory even if it is double insulated just in case!
Sy

 

[Robotstar5]

Doesn't anyone use the metal trunking and conduit as CPC these days?

 

[sparkysy]

We don't any more as we have no proper way of testing it's integrity, and parallel paths can give you low readings that may not suitable under proper fault conditions.
Sy

 

[123hotchef]

that is how they use to install them steel conduit as earth and neg and pos wires pulled through had the same problem in the mrs flat ended up rewiring the lot and pulling through extra earth bonding