Discuss Chasing in and trunking? in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

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Nobbin

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I've been on a few jobs where a previous installer has chased in some 25mm trunking instead of the 25mm oval conduit that I would normally use. I don't like capping as it's a bugger to send new cables through.
Just wanted peoples opinion of best practice when it comes to mechanical protection below 50mm in wall chases. I may be looking in the wrong place but I can't see any guidance on this other than cables less 50mm deep require either RCD protection or metal capping. I'm guessing the plastic capping and conduit is something we do as best practice to protect the naked cable from slap dash plasters?

Cheers in advance for your words of wisdom.
 
Ordinary metal capping isn't deemed adeqate as mechanical protection. 3mm steel seems to be pretty much the accepted industry standard for mechanical protection. An earthed metallic bit of containment like conduit or trunking would be adequate because it's earthed. If it's just buried in the wall and not earthed then the metallic trunking/conduit would not be adeqate to omit the 30mA RCD protection. Capping is used to protect the cables from plasterers but obviously also serves the purpose of holding the cable to the wall. For me if it's being chased then oval conduit is used, if it's a new wall that's either going to be float and setted or dot and dabbed then it gets capped.
 
Oval for me and on the odd occasion I’ll go all proper and go 20mm conduit into the metal backbox with a bush coupler, “proper job” - Andy from scrapheap challenge.
 
In Northern Ireland we can get oval conduit no problem. PVC/PVC Single Brown, Blue, Blue/Earth, Brown/Earth, Twin Brown. But good luck trying to get 1.0mm T&E. Or top hat capping, wholesaler don't generally stock that either.
 
Should add general method of installation is 20mm light gauge conduit chased into walls. On new builds no dot and dab, walls are sand and cement floated out before skimming.
 
In Northern Ireland we can get oval conduit no problem. PVC/PVC Single Brown, Blue, Blue/Earth, Brown/Earth, Twin Brown. But good luck trying to get 1.0mm T&E. Or top hat capping, wholesaler don't generally stock that either.
Wouldn't say oval's common here. I'm pretty sure it would be a special order if I wanted it.
 
Wouldn't say oval's common here. I'm pretty sure it would be a special order if I wanted it.
To be fair, when I order it I only order 1-2 lengths of it as oppose to 20mm round light gauge, which I'd order by the bundle. Very seldom use the oval, it has it's uses but they are very infrequent.

I'd probably use about oval 15m a year, capping 2m a year, round conduit a few thousand metres per year.
 
I generally use oval, however I do chase trunking in the wall but only for 1 purpose.

I use mt4 trunking quite often when the customer decides they might want to mount the TV to the wall.
Quite often I'll put a brush plate high level and a brush plate low level and chase a couple of bits of mt4 between.
I've found that the right shape a size to be able to thread hdmi cables through if need be.
 
Oval and capping are the norm around here.

Oval for additions in existing walls and capping for extensions/new builds where walls are to be dot and dabbed.
 

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