A Voltimum user wanted to settle a difference in opinion related to confirming the condition of conduit embedded in a concrete slab. ECA's Gary Parker waded in to help.
This Q & A is one of thousands posted in our Technical Expertise area, and answered on a daily basis by our Voltimum Experts.
Question:
I am rewiring a lighting circuit through conduits that were installed about 40 years ago and are embedded within the concrete slab of the building,I cannot access the joints of the conduit so cannot confirm their condition, does regulation 526.3 imply that a CPC should be drawn in with the circuit wiring, we have a difference of opinion on this topic, your opinion would be much appreciated ...
Regards,
J. Murphy
Answer:
Gary Parker - ECA
Hi there.
Section 526 talks about electrical connections, to me that means something with a cable. I believe 526.3 refers to electrical connections and terminations. If you can prove that the conduit is continuous, there is no harm in using that as a CPC, 543.2.1 allows this.
Personally. I would see no issue using the metallic conduit here, as long as you can prove continuity.
Question:
Hello Gary and thank you for your opinion on the earthing of the conduit in a concrete slab. My only reason for thinking this does not comply with regulation 526.3 is that it states EVERY connection shall be accessible for inspection, testing and maintenance, except for the following:
(1) joint designed to be buried in the ground
(2) compound filled or encapsulated joint
(3) connection between a cold tail and a heating element etc.
(4) a joint made by welding, brazing soldering etc.
(5) joints and connections made in equipment by the manufacturer etc.
(6) equipment complying with BS 5733 (maintenance free accessory )and marked accordingly
I cannot see that steel conduit falls into any of the above listed category's and as it will be the sole CPC conductor, I personally feel that this regulation definitely refers to steel conduits and the like.
It is not a problem to pull a CPC through the conduit but I am just curious for future reference ...
Regards,
J. Murphy
Answer:
Gary Parker - ECA
I can't deny your logic on this, you are quite right in what you are saying. However, as many conduits are embedded in walls, floor etc. these would never be accessible but the chance of them ever becoming loose is minimal. A screw connection in a conductor where the copper migrates or, for a live, AC is running through will always become loose over time.
If you can pull a CPC through, then great but I wouldn't think it is the intent of the Regulations that the conduit should be accessible.