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Radial lighting circuit switch cable connections (short cut maybe)?

Postby BubbleGum* » Thu Aug 20, 2020 8:13 pm

Hi,please be patient,is this a short cut procedure performed in the 70's.
2 cables into light switch,one modern grey pvc,red into common,blk cut off.Other cable is black soft outer sheath,red into other connection,blk not used.
Is this ok,all other switches only have one cable?
Without stating the obvious (rewire).
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Postby Mr White » Thu Aug 20, 2020 9:41 pm

Can't help but wonder why it was done, that we will never know.

The only "problem" is the condition of the cable with the soft outer sheath.
Is this cable showing signs of wear?
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Postby ericmark » Fri Aug 21, 2020 7:37 pm

As Mr White has said around mid 50's we moved from rubber to PVC, and the old rubber cables are by now coming to end of life, there were also so poor PVC cables where the plasterer leached out, but if left alone they are normally OK.

In 1966 the rules changed on lights, before that date no earth was required for lights, after that date an earth wire must be fitted even if not used, so no earth mean pre-1966.

Heat can damage cables, and you can still get the odd rubber cable which has been cool all it's life still OK today, but we are told we should test the installation every 10 years or change of occupant, now it seems government has reduced that to 5 years for rented property.

Use of RCD protection has changed the risk, so even without earths today installations are safer but again the RCD needs testing, and I will be honest my RCD tester has gone up the creak so my RCD's have not been tested as they should be. However all my house is protected, even if some circuits have the wrong RCBO (RCD and MCB combined) fitted.

I had mothers house rewired, did not do it myself for two reasons, one the cost of notifying the LABC and the other speed, it was a basic rewire cost around the £2000. House last wired 1954, rubber cables and no earths to lights. It was mainly done in case we needed to let the property, however when mother died it was sold.

We could not fit RCD protection before the rewire, the units simply would not hold in, and before rewire the house was dangerous, my dad refused point blank to let it be rewired he said you can do that when I am gone.

Around that house there were many botches, my dad was an engineer and thought he knew how to add sockets, etc. And there was a right mixture, during the rewire mainly to reduce decoration after some cables were reused, those fitted after 2004 when colours changed.

So in your case you need to decide next step, you can take photos and post them on a forum, but photos don't tell anyone if insulation is crumbling.

A year ago I would have suggested an EICR but new laws has resulted in 1000's being done at this time, and often they are not done well, it is just a bit of paper needed to rent property, so maybe better to simply ask an electrician to look at that one item.
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Postby BubbleGum* » Fri Aug 21, 2020 10:09 pm

Thank you for the two replies,however my question relates to the terminal connections in the light switch.
1, single one way switch in my living room.
My question is,why are their two cables,one going to the ceiling lamp and the other going to a JB.
What is even more alien to me,is the way the cable connects to the switch.
Can I deal with the cables separately,the red core of the grey (lamp) to
Common,black is just cut and not connected.
TRS cable red core to L1 and the black core not used,which goes to JB.
Question,why are their two cables going into the switch,with the two black cores doing nothing.
Please enlighten me,many thanks.
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Postby BubbleGum* » Fri Aug 21, 2020 10:19 pm

Forgot to mention, the cables I have changed are surprisingly good for their age,showing little signs of wear,as I had started this renovation some years ago I thought while I was pulling things to bits I would update the wiring.
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Postby Mr White » Sat Aug 22, 2020 10:18 pm

I have already answered your question in my first reply.
Mr White wrote:Can't help but wonder why it was done, that we will never know.


Despite what most folk assume there is no regulation or law that says how you should wire lights, it is up to the person doing it how it is done. The regulations only say about cable size, clipping, protection etc.
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Postby BubbleGum* » Sun Aug 23, 2020 1:07 pm

Thank you for your reply.
I have absorbed what you have said in regards to wiring methods etc.
As a lay person who has a very open mind,I still do not understand why you would have two core 1mm and two core and earth going into a light switch,and only 1 conductor being utilised from each cable??
As I mentioned in my 1st post.
Many thanks
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Postby Mr White » Sun Aug 23, 2020 2:26 pm

You may have
BubbleGum wrote: absorbed what you have said in regards to wiring methods etc"
but obviously not understood.

As I have already told you, it is up to the person actually doing the job how they do it, and since it was not me, and not you, all that can be done is guess, and even if you do guess, you will never know if you have the correct answer.

It will have to remain as one of life's mysteries.
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