Do I need to test an old wiring installation?

[GLENNSPARK]

Ah the dreaded board upgrade, that's why I don't do domestic systems, but have to agree with many of the comments though..

1: Quote to Test and Inspect the installation prior to undertaking any work, explain that if you simply upgrade the board this does not automatically make the installation safe, only safer, but it could introduce problems that are them expensive to solve, such as faults causing nuisance tripping than BS3036 or other types of fuses would ignore.

2: Quote for the rewire and include the costs of the CU upgrade (Explain this included the costs of a post installation test and certification anyway). I would sweeten the pot with a couple of smoke detectors and a heat detector (kitchen) thrown in free (if gas in kitchen consider a combined heat/CO2 detector)

3: Quote to only do the board, but state that you would not be prepared to undertake the works without testing it first because you are legally responsible and you could not in all conscience undertake any work you consider to be substandard.

Remember to explain the merits of rewiring the house, this does make the home safer, it may decrease their home insurance policy and it also means it will not be necessary for about 20-25 years so actually will help the sale of the house should they choose to sell at any point.

only if the existing installation fails

stop it...no hard sell ....it isn`t windows n doors you know....

 

[Outspoken]

only if the existing installation fails

stop it...no hard sell ....it isn`t windows n doors you know....

Get off your soap box, there is no hard sell in explaining reality should the installation fail any tests, but if the installation is more than 25 years old it should be rewired anyway and the test would be largely irrelevant.

 

[monkeyelectric]

Get off your soap box, there is no hard sell in explaining reality should the installation fail any tests, but if the installation is more than 25 years old it should be rewired anyway and the test would be largely irrelevant.

Why should it be rewired if over 25 years? If all test confirm wiring is ok there's no point

 

[Outspoken]

Why should it be rewired if over 25 years? If all test confirm wiring is ok there's no point

Because PVC cable loses it's plasticiser over time and can become brittle, it loses some of it's insulating abilities and if you bother to read the regs it actually states this as a recommendation. Not a hard and fast rule, but it is a sensible one.

 

[monkeyelectric]

Because PVC cable loses it's plasticiser over time and can become brittle, it loses some of it's insulating abilities and if you bother to read the regs it actually states this as a recommendation. Not a hard and fast rule, but it is a sensible one.

So even if it tests out ok after 25 years you would still advise a rewire? do you ride a horse and wear a mask to work?

 

[monkeyelectric]

Because PVC cable loses it's plasticiser over time and can become brittle, it loses some of it's insulating abilities and if you bother to read the regs it actually states this as a recommendation. Not a hard and fast rule, but it is a sensible one.

I must admit i've not seen that in the regs, enlighten me?

 

[Outspoken]

I must admit i've not seen that in the regs, enlighten me?

When I get home I will find where the comments are in the current regs books.

However in the meantime

There are no requirements for life expectancy set out in cable standards and specifications. However, reputable cable manufacturers will state a probable life expectancy for their products, which for building wiring is usually 20 years when run at the rated temperature. However, under ideal circumstances, with lower loadings and minimal heating, it has been observed that cables can remain safely in operation for up to 50 years.
Cables degrade over time primarily due to changes in the polymers used for insulation and sheathing. The main cause of polymer degradation is too much heat, from either excessive current loading or from the environment - such as heated spaces. Cables loaded or heated for 24 hours a day will degrade faster than those used only during working hours – for example, commercial lighting circuits are often operated continuously.

LINK

 

[Andy78]

I think we all know what can happen to cables, but like monkeyelectric has said, testing and inspection will confirm whether or not they are suitable for continued service. If you are concerned about old cables that test out fine, then more regular periodic testing of the installation would be advisable, not a rip out and start again job when it isn't needed.

 

[Outspoken]

FFS, did I post in Chinese Guys, I did not say they should have it rewired, I said it should be a recommendation and at no point did I say it should not be tested first...I seem to recall the first item on my list was a quote for Testing!!

 

[Stroppy]

Don't take it personally, it is like this all the time round here.

The Basec thing states:

for building wiring is usually 20 years when run at the rated temperature. However, under ideal circumstances, with lower loadings and minimal heating, it has been observed that cables can remain safely in operation for up to 50 years.

I can't imagine many domestic installations run at 70 degrees as a matter of course. If I found my cabling was around that temperature normally I wouldn't be happy!

 

[Outspoken]

Don't take it personally, it is like this all the time round here.

The Basec thing states:



I can't imagine many domestic installations run at 70 degrees as a matter of course. If I found my cabling was around that temperature normally I wouldn't be happy!

Thanks for falling into the trap...I was hoping you or someone would make the comment about Polystyrene insulation or glass fibre insulation as used in domestic premises as both have seriously detrimental effects on PVC cable, and it's even worse for LSF cables. Of course the cables do not run at their maximum potential and any sane person would be horrified to find them doing so. Just as you de-rate cables even if they pass through a different medium for a short length, so you need to take the insulation of the home into account, and to be honest the IR tests may not show up any shortcomings.

Obviously if your able to completely visually check all cable runs that are not in wall life is simpler, but this is the real world, and as i have said, it is a recommendation not a requirement...two totally different things.

 

[snowhead]

Quick, where's the Screwfix catalogue, my house is 26 yrs old this year.

 

[stuartcourt]

I have read the same as you about insulation on cables and have re-wired thousands of homes, as yet have never seen where insulation has damaged cables, has anyone, this is a question not an attack

 

[oldtimer]

Because PVC cable loses it's plasticiser over time and can become brittle, it loses some of it's insulating abilities and if you bother to read the regs it actually states this as a recommendation. Not a hard and fast rule, but it is a sensible one.

I think you are talking about the T&E that has aluminium cores in them plus I have just put in a new CU for a landlord in an occupied property that I judged to be at least 25 y.ears old but the problem was the landlord wanted a new CU and kitchen fan in and that was it. I tested the property and found lowest IR was 148 ohms.(the rest were 299,250)

Now in the ideal world the house should have been gutted but the reality is the landlord would have to wait for the tenant to leave so decided to improve the property by taking the 3 x 3036 DBs out and fitting a safety CU yes a compromise but for me I left a property much safer and when the property is vacant the landlord may decide to get it rewired

 

[Outspoken]

I think you are talking about the T&E that has aluminium cores in them

Never seen T&E with Al cores, only Cu. The Only Al core cable I have dealt with has been on HV installations.

 

[oldtimer]

Never seen T&E with Al cores, only Cu. The Only Al core cable I have dealt with has been on HV installations.

You need to get out more lol

 

[Outspoken]

You need to get out more lol

Nope, must be a Scottish thing as they have never factored down here, the nearest is the old tinned T&E that was imperial and made in the 1950's/60's..are you thinking about that because I know some people believed it was Al but it wasn't, only AL coated Cu. In the mid 70's there was a cu shortage and some manufactures used Cu coated Al cores, and that cable was seriously pants and prone to snap!!

If you check BS7671 you will see that the minimum size of Al conductor is 16mm²

 

[snowhead]

Aluminmium T&E was available and used in the 70's in England

 

[Outspoken]

Aluminmium T&E was available and used in the 70's in England

I take it you did not read my previous post then...

 

[oldtimer]

Aluminmium T&E was available and used in the 70's in England

Remember the old VIR cable had Aluminium/tinned cables so when PVC came to the for the kept the cable then introduced copper