Metal conduit between two light fittings

I would say yes. If the live scags the exposed conduit it will become live if it isn't earthed.

Gary

if the cable inside the conduit is normal singles then I'd say definitely yes too - the earthed conduit is the necessary 2nd line of defence.

Perhaps if it was T& E or something, it would be arguably less important and just a floating conductive part.
Or if the conduit was designed and treated like a live bus bar and in a suitable enclosure. 

I suspect neither applies, so get those pirahna nuts at the ready ;-) 

Mike.

Is this a real issue, or just an office debate?

What the lamp fittings are made of, even if they are double-insulated, is irrelevant. The risk arises from the cables passing through the conduit.

Only exceptions I can think of if is the circuit isn't normal LV - e.g. SELV or perhaps separated LV, or (very rarely) if the conduit was out of reach (unlikely in uncontrolled environments like normal offices).

   - Andy.

Hi Chris, It is a real issue, we are installing earths to the ends of the conduits hence why it started the discussion. they area GRP linear fittings the span is approx 1m of conduit at around 3m ceiling height

If I have visualised the situation correctly, the metal conduit would appear fall within the definition (BS 7671 Part 2) of an exposed-conductive-part:

'Conductive part of equipment which can be touched and is not normally live, but which can become live under fault conditons'

As an exposed-conductive-part, connection to a protective conductor would be required by 411.3.1.1.

If not connected to a protective conductor, you would only have basic protection (provided by the insulation of the conductors within the metal conduit) but you would not have any fault protection in the event of failure of the insulation, the classic 'single fault to danger'.

Some exemptions to the provision of fault protection are listed in 410.3.9 (i) to (v) but none would appear to apply in the situation described. 

- Ross

Ross has summed up the Regs very well. Mind you, I struggle to see how a fault could arise within the conduit unless mice could find their way in.

Would PVC conduit not be simpler?

Hello Chris:

Your question that PVC conduit would be simpler -- is the right answer and cheaper too.

Over here in the US we have flat rectangular PVC conduit 

Peter Brooks

It would be if the conduit wasn't already there. We are simply swapping lights over on an existing installation. The original conduits were not earthed and we connecting fly leads via the lock nuts to the terminal of the fittings. The question was raised in the office weather there was a requirement to do so, but as all here have agreed with the majority of us. It has validated what we are doing. Thanks all!

Hello Mark:

Just for my education "why" and "what" are you swapping the office lights from - to.

Peter Brooks