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Posted By Topic: Not using the Yellow conductor - 3.8.2

gregwires
Dec 21 2018 14:01

I’m looking at a proposed pump shed replacement, the shed is currently supplied by 130 meters of NS cable that is run in PVC pipe (buried and marked) from another building. The current cable uses yellow for l2 (3 phase pumps). The new building and pumps are not on exactly the same site (~5m move) so the existing cable would need some re-routing at the load end. Because of these collective changes I’m considering this is a new installation and as the coloring of the existing cable is no longer compliant it can't be re used.

Question, can only the yellow conductor be retired from service and a single NS cable be pulled through to replace it, i.e. use the Red and Blue of the existing cable and a new white for L2.


Happy to be told I've interpreted remain in service incorrectly too.


   

pluto
Dec 21 2018 14:56

Sleeve the yellow conductor with white sleeving at the end you intend to relocate as youu are aonly converting a yellow phace conductor to a white phase conductor.

I note you eais that a 3 phase motor was being supplied by the cable.

3000 cl 3.8.2 refers.
   

gregwires
Dec 21 2018 15:24

Thanks Pluto,

Yes, three phase pumps there, whole setup is functional and working but a change in pumps is having knock on effects.

I was not keen to sleeve because of A1 of 3.8.2 - “Sleeving or other means shall not be used at terminations or along the entire length, to identify a green, yellow or green/yellow colour-insulated conductor as an active or neutral conductor.”

It was also suggested to me to me that many people would just just cut it off and join in new cable, i.e.in this case leave 110m of the original cable in service. I had problems considering this as valid as the cable is not used as it was installed.
   

DougP
Dec 22 2018 07:52

The sentence in 3.8.2 that you refer to seems to be an oversight and there has been an additional clause(s) added to 3000:2018 to correct this.

The new clause:
3.8.2.3 Sleeving of existing live conductors
In electrical installations where conductors with yellow insulation have been previously installed as live conductors, complying with previous editions of this Standard, such conductors with yellow insulation may remain.

When alterations or repairs are carried out that result in new terminations or junctions to those existing live conductors with yellow insulation, such live conductors with yellow insulation shall be sleeved with white sleeving within each of those new cable junctions or terminations.
   

pluto
Dec 22 2018 10:26

Remember as/nzs 3000:2018 is not cited in NZ and it is not likely to be cited until at least late 2019 so legally it dose not apply.

The new 3000:2018 has no legal status in NZ, but it is unlikely that Energy Safety or EWRB would take action if a new provision was used AND it did NOT make an electrical installation Electrically UNSAFE.
   

AlecK
Dec 22 2018 12:05

We don't need the new (2018) bits of 3.8.2 to allow existing yellow actives to remain; because ESR 113 does it already.

And you are technically correct that re-routing the cable could well be installation work; in which case both editions ban the installation of a yellow active, and ban the sleeving of the yellow for the installed length of cable.

One answer would be to cut the cable at point of diversion, and lay new, compliant cable to new pump location. In that case sleeving the existing yellow at the junction as an active colour would be optional -you don't have to, because 2018 edition is not mandated (yet), but you probably should, as it's clearly better to sleeve than not .

However since the work appears to be replacement of fittings (pumps), and the movement is only 5 m in 130 m; I think you can safely call it replacement, for which ESR 6A allows repositioning of conductors to facilitate replacement. There's no absolute rule that determines where relocation to facilitate replacement of fittings (ESC) suddenly turns into new installation work (CoC & ESC). And given that any joint increases the chances of future fault, this is a superior solution to cutting and installing a new section of cable.

In this case, sleeving is prohibited by current edition, which is legally mandated; but I agree with pluto that "authority" isn't going to pick you up on it. They'll never even know, unless something goes horribly wrong.