Hey Team,
Was just a job the other day a saw some oldish TPS which was solid core 2.5mm primary insulation on the earth as well, not bare earth in sheath.
What date did the standards prevented the uses of solid core cable other than 1mm? Just want to get a better upstanding of when types of cable were in use.
Furthermore, the work I was doing wasn’t on the said conductors but likely to go back in future and it got me thinking.
Am I right in assuming, that even though this type of cable are now prohibited, that as it was compliant at the time of installation that as long as the cable is electrically safe that it can remain in service, repaired, maintained etc and not required to be removed?
The ESR number escapes at the moment regarding existing works, fittings, installations and appliances (often referred to as “grandfather” clause) that governs these types of things.
I know many companies sell to customers that there house or property “is required by law” to be rewired as the cable is now “illegal”. I am not disagreeing that damaged or old cable (VIR or TRS) is a risk, but that is there statement of it being legally required to be removed as untrue, unless that cable is electrically unsafe?
Obviously if insulation breaking off conductors or brittle when moved, which as we all know is common then clearly it is electrically unsafe. But the mere presence of said cables does this constitute the explanation that it needs to be removed?
I hope that question made some kind of sense, thought I ask here as the Facebook pages are getting a bit punishing and the knowledge here is great.
Old cable types
Re: Old cable types
Hi Chaz, if you are talking about the white 2.5m 2C + E TPS, it came out in the seventies (I was just finishing my apprenticeship), it was manufactured when the cable sizes transition from imperial to metric and it was very difficult to work with. It wasn't around along and got changed to the present day multi strand not long after it first appeared (probably because it was so hard to work with), I cant remember it been prohibited though, there wasn't standards in those days only wiring regulations.
The regulation you were thinking of is 113.
The regulation you were thinking of is 113.
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Re: Old cable types
PeteRig's correct that single-strand conductors have never been prohibited in NZ.
Also that ESR 113 allows anything that
- complied when installed;
- still complies with original rules; and
- is not electrically unsafe
to remain in service.
There's no history of widespread failure / deterioration of this type of cable.
So absolutely untrue that it must be replaced.
WRT cable for new work / alterations; most forms of "building wiring cable" up to 16 mm2 are DMRAs, therefore an SDoC is required for sale / supply in NZ [ESR 83].
The SDoC will claim compliance with a relevant Standard listed in Schedule 4 of ESRs .
Clause 4 of Schedule lists cable Standards; TPS will generally be to AS/NZS 5000 seroes
and must also include info on where the test certificate that proves compliance can be found.
It may well be that the manufacturing Standards for cable no longer allow for single-strand above 1 mm2
(which is completely different from a prohibition under ESR 87).
Or it may just be that it was discontinued in response to market forces.
It's my understanding that a couple of States in Oz do not allow single-strand 1 mm for earthing, so their TPS has solid A & N but stranded E.
I agree it was difficult to work with; partly due to being less flexible, but mostly because many accessories of the time had smaller terminals.
Putting 2 x 2.5 mm2 conductors into 1 terminal of a PDL 60 or 61/U/2 socket outlet could only be done by keeping then straight (no twisting)
and if you tried doubling a single back on itself, had to squeeze the hell out of the bend to get it in.
Also that ESR 113 allows anything that
- complied when installed;
- still complies with original rules; and
- is not electrically unsafe
to remain in service.
There's no history of widespread failure / deterioration of this type of cable.
So absolutely untrue that it must be replaced.
WRT cable for new work / alterations; most forms of "building wiring cable" up to 16 mm2 are DMRAs, therefore an SDoC is required for sale / supply in NZ [ESR 83].
The SDoC will claim compliance with a relevant Standard listed in Schedule 4 of ESRs .
Clause 4 of Schedule lists cable Standards; TPS will generally be to AS/NZS 5000 seroes
and must also include info on where the test certificate that proves compliance can be found.
It may well be that the manufacturing Standards for cable no longer allow for single-strand above 1 mm2
(which is completely different from a prohibition under ESR 87).
Or it may just be that it was discontinued in response to market forces.
It's my understanding that a couple of States in Oz do not allow single-strand 1 mm for earthing, so their TPS has solid A & N but stranded E.
I agree it was difficult to work with; partly due to being less flexible, but mostly because many accessories of the time had smaller terminals.
Putting 2 x 2.5 mm2 conductors into 1 terminal of a PDL 60 or 61/U/2 socket outlet could only be done by keeping then straight (no twisting)
and if you tried doubling a single back on itself, had to squeeze the hell out of the bend to get it in.
Re: Old cable types
Thanks Alec / Pete for the responses.
So same applies to VIR /TRS also as long as electrically safe?
However prudent to replace.
So same applies to VIR /TRS also as long as electrically safe?
However prudent to replace.
Re: Old cable types
Yes; exactly the same application of ESR 113.
If the cable has become electrically unsafe, then it is no longer permitted to remain in service.
But not that the definition of 'electrically unsafe' [ESR 5] sets a high bar;
there has to be "significant risk" of either "serious harm" or "significant" property damage.
Just getting a bit old, and even knowing that similar cable in some other installations has been a problem, is not enough to make it 'electrically unsafe".
Most TRS needs only minor remedial work at terminations, eg sleeving the cores; rather than replacement.
And that's often limited to locations where it's been subjected to heat, typically at lights; with the rest being perfectly OK.
Actual gradual deterioration of core insulation is much less common; and generally limited to where the sheath has been stripped back .
That said; I've seen one case where both the (white) sheath and the core insulation within had gone brittle, and crumbled off at slightest movement.
So clearly TRS isn't all the same, and there must have been some differences in the exact make-up of the "rubber" mix used at different times or by different manufacturers.
In my view if it hasn't deteriorated by now, after 60 -odd years in service, it's unlikely to in future.
One way of mitigating the risk is to install AFDDs.
Much cheaper than re-wiring; which can then be postponed until there's an actual problem with a particular circuit.
If the cable has become electrically unsafe, then it is no longer permitted to remain in service.
But not that the definition of 'electrically unsafe' [ESR 5] sets a high bar;
there has to be "significant risk" of either "serious harm" or "significant" property damage.
Just getting a bit old, and even knowing that similar cable in some other installations has been a problem, is not enough to make it 'electrically unsafe".
Most TRS needs only minor remedial work at terminations, eg sleeving the cores; rather than replacement.
And that's often limited to locations where it's been subjected to heat, typically at lights; with the rest being perfectly OK.
Actual gradual deterioration of core insulation is much less common; and generally limited to where the sheath has been stripped back .
That said; I've seen one case where both the (white) sheath and the core insulation within had gone brittle, and crumbled off at slightest movement.
So clearly TRS isn't all the same, and there must have been some differences in the exact make-up of the "rubber" mix used at different times or by different manufacturers.
In my view if it hasn't deteriorated by now, after 60 -odd years in service, it's unlikely to in future.
One way of mitigating the risk is to install AFDDs.
Much cheaper than re-wiring; which can then be postponed until there's an actual problem with a particular circuit.