I am a carpenter. I like chamfered dado trunking but would like to custom make some for my home using timber instead of the typical plastic product in shops.

Is there any safety differences in using timber as trunking. Considering many electricians run 2.5 under floorboards, behind walls and along joists, i am seeking a little clarity as there appears no definitive answer online elsewhere.

(Work will be carried out by a certified electrician, my question here is to better understand any difference as i wish to make said trunking. )

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    There May be local regulations, ask your electrician. Personally I consider thick wood much more fire safe than non fire retardant plastics – PlasmaHH Sep 4 '16 at 12:01
  • It's a good idea to think about clearing paths for wires before the electrician shows up. But they will only lay wires in raceway products listed for that purpose (CE, UL, CSA etc.) Homebrewing such a product is right out. There certainly are definitive answers, as any Anglo or European country has official Code books. The EU more than most, heck even Russia is harmonizing their electrical code to EU. (Even the USA is harmonizing to EU, allowing blue for neutral inside appliances). – Harper - Reinstate Monica Sep 4 '16 at 16:53

I am guessing this is partially driven by an aesthetic concern?

Plastic trunking isn't used for safety, it is used for cable management and routing. Where there is a safety concern (ie buried cables in non-safe zones) then earthed metal trunking is required.

There is nothing wrong with using other types of trunking & you can already acquired wood/wood-effect trunking.

enter image description here

Just be aware, if such "trunking" is outside of the safe zone it is not so inconspicuous that others may not consider there any cables. Has the end effect resulted in essentially a buried cable consideration simply because of the nature of how you concealed the cables.

Cables in a wall or partition

  1. A cable concealed in a wall or partition must be at least 50mm from the surface [If the wall or partition is made from or partially made from metal then the cable will require RCD protection or be installed as 2), 3) or 4) below]

  2. have earthed armouring or an earthed metal sheath (eg SWA, a BS 8436 cable or MICC cable)

  3. be enclosed in earthed steel conduit or trunking
  4. be provided with mechanical protection (3mm steel is deemed sufficient to meet this requirement)

The safe zones for cables concealed in walls are

  1. a horizontal zone within 150mm of the top of a wall
  2. a vertical zone within 150mm of the angle formed by two walls - e.g. internal and external corners.
  3. the horizontal and vertical zone adjacent to an electrical accessory (switch, socket, cable outlet etc) enter image description here
  • Many thanks. As i had seen you can purchase some types but with my not knowing about the conditions and general rules i had reservations. The trunking is to be external to wall with a series of twin outlets along. Reasoning for the home made is skill and design choice. The room including the trunking are to be vented with extraction. So temperature wasnt a huge concern but indeed was a marker among my query. Excellently answered. Thanks again. – Derple Sep 4 '16 at 13:45

It's not clear what you are really asking (what is "trunking", "2.5"?), but power cable is routinely run in wood-framed houses by being fastened directly against the wooden supports. Safety has already been built into the current the cable is allowed to handle and the circuit breaker ratings to prevent it getting anywhere near hot enough to cause a problem being right up against wood.

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    My guess is "trunking" is what we would call "conduit" in the US. I have no idea what "run 2.5 under floorboards", etc. means. – Dave Tweed Sep 4 '16 at 14:14
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    chamfered dado trunking is common for PVC enclosed perimeter wiring for ceilment and is impact resistance with white or wood tone finish. Wire self heating at max current may increase temp. somewhat. e.g. stone walls might use these in uk. – Tony Stewart Sunnyskyguy EE75 Sep 4 '16 at 16:18

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