How to test a circuits in steel conduit as the cpc

Questforknowledge · Feb 27, 2019

Good evening

I am currently a training to become an electrician. I do hold both initial verification and periodic testing qualifications however this is an issue I have never personally had to deal with and was never mentioned on any of my courses as often seems to be the case.

Basically I am wondering how you would hypothetically go about testing either a ring or radial circuit if you didn't have a seperate cpc but the conduit itself acted as this.

Look forward to hopefully getting a response and some clarity

Regards Harry

westward10 · Mar 2, 2019

Ian1981 said:
To limit the touch voltage to below 50 v

This is my view.

Ian1981 · Mar 2, 2019

westward10 said:
This is my view.

Yes I do see your point.
My explanation of section 419 could have been clearer

westward10 · Mar 2, 2019

You are always clear Ian tis my mind that isn't, all that tinnitus.

spark 68 · Mar 2, 2019

There are basically two reasons for SB, the special locations part is to do with reducing Ut to keep it below 50V, medical locations below 25V, back in the 16th agricultural locations required Ut below 25V as well I recall, but I don't recall now which specific amd, or if it ever changed in that entire edition.
The other part is to achieve disconnection times and was to reduce Zs by default, the regs are worded --- backward in a lot of cases.

westward10 · Mar 2, 2019

Find your early 16th and see what is says.

Ian1981 · Mar 2, 2019

spark 68 said:
There are basically two reasons for SB, the special locations part is to do with reducing Ut to keep it below 50V, medical locations below 25V, back in the 16th agricultural locations required Ut below 25V as well I recall, but I don't recall now which specific amd, or if it ever changed in that entire edition.
The other part is to achieve disconnection times and was to reduce Zs by default, the regs are worded --- backward in a lot of cases.

I can’t even remember the 16th that well
Wish I had kept my yellow copy I used to pass the exam.
What I do remember from that time is the awful bonding and in particular the radiator clamps we used to supplementary bond the bathrooms
Looked hideous if you couldn’t hide them

westward10 · Mar 2, 2019

The yellow copy it is deleted but @spark68 has an older copy mine are in the loft.

spark 68 · Mar 2, 2019

I could dig them out Westy, but what do you make of the second part of reducing disconnection times ? this part has nothing to do with Ut or special locations.

westward10 · Mar 2, 2019

I am not sure that is the intent but it will probably result in doing so.

westward10 · Mar 2, 2019

Have I got to get in the ****ing loft.

spark 68 · Mar 2, 2019

No, I could get my 16th editions out, but as the disconnection times part are still in the current edition and GN8 for the 17th amd 3 there is not much point really, I will look up the regs spin posted up later, and see what actually changed.

westward10 · Mar 2, 2019

So I have been in the loft and after looking for a red book realised I had a blue hard back copy.

[ElectriciansForums.net] How to test a circuits in steel conduit as the cpc

PEG · Mar 2, 2019

freddo said:
A ductor tester should be used to check the condition of the conduit joints. Test current of 100A should be fine.

ONLY after full RA and discussion with those fully aware of possible downside of such a test

Deleted member 26818 · Mar 2, 2019

This is the latest version:
419.3 Except where Regulation 419.2 applies, if automatic disconnection cannot be achieved in the time required by Regulation 411.3.2.2, 411.3.2.3 or 411.3.2.4 as appropriate, supplementary protective equipotential bonding shall be provided in accordance with Regulation 415.2 and the voltage between simultaneously accessible exposed-conductive-parts and/or extraneous-conductive-parts shall not exceed 50 V AC or 120 V DC.

spark 68 · Mar 2, 2019

In the brown book 16th 413-02-15 is deleted in 1992 amd2

This reg is present in the green book amd1: 1992 16th though, and says pretty much the same as the blue book above (which I also have).

The 16th was a bit strange as there was at least one reset in between the green book amd 1 :1992, the blue book :2001 (no amd given even though it is almost a decade later) and the brown book :2004 both amd 1+2