Does the pipe, i.e. conduit, have to go underground given that it starts and finishes above ground? Could it, perhaps, be attached to the wall.

There is certainly no reason why the conduit cannot be attached to the wall - we have it at home. It should be all right in concrete although I would want it to be reasonably dry.

Either way, the conduit must be earthed.

It needs to go underground as it must go below the fireplace. Thanks for reminder about earthing.

What exactly does "below the fireplace" mean. Clearly, the conduit cannot be so close to the hearth that it gets fried, but if the ambient temperature is elevated at all, the cables may need to be thicker.

If at all possible, I would avoid making any joint in the pipe run.

It will be approx 250mm below the fireplace which is a wood burner so not in direct contact with the floor. Do you think that would cause a problem? It would be possible to go deeper

This sounds like it is containment for the supplier's cables on 'their' side of the meter, so in the UK BS7671 wouldn't apply to arrangements for the supplier's cables.  Best verify with the supplier om the details of the proposed route as they will need to happy with what you install.

Jason.

Provided the cable inside the pipe is insulated and sheathed (i.e. can be deemed to provide protection from electric shock by means of double/reinforced insulation) then technically the pipe won't be an exposed-conductive-part and so there's no need for the pipe to be Earthed on that score. In some places around the world it's common to see lengths of straight steel conduit used in lieu of cable clips.  Being underground it may well additionally need a surrounding earth/c.p.c. (and some upstream means of ADS) but if the cable is armoured or concentric construction that requirement could be satisfied by the cable itself so again no need to specifically Earth the pipe. If it's running underground and then exposed inside the installation it may well need to be main bonded (but the size calculation for that is quite different to that for a c.p.c.).

If you have a TT Earthing arrangement I'd be very wary of allowing the pipe to be an exposed-conductive-part and connecting it to the consumer's earthing system unless the supplier provides and upstream RCD (as EdF do in France) - a fault would make the entire earthing system permanently hazardous live.

     - Andy.

Any joints in the underground pipe would need to be watertight, so use PTFE tape on the threads. Also would be a good idea to do an air tightness test like that done on drains. And put a drawer cord in when assembling.