Old wiring in 1970's house - advice sought

Andy From Sligo

Hi, moved into rented bungalow last June - the bungalow quite old 1970's Id say and the mains wiring is Black & Red - no earth going up to all ceiling roses (earth wire on living room metal ceiling lights and brass wall lamps) Black and red going to 13a sockets, no earth to any light switches, an earth wire fixed to the leg under the metal/cast iron bath but from what I can see no earth bonding under the kitchen stainless steel sink and on the cold and hot water copper tap pipes nor no earth bonding on the copper pipes in the airing cupboard/hot press. The fusebox looks like its been updated at some stage with a Hager consumer board with MCB's and main RCD. I used to hear in UK about old houses that the old Red & Black wiring had a lifespan of 25 years because insulation and everything broke down over time and that the whole of the house needed re-wiring. There was a PRTB check done by the landlord which was supposed to have included a Electromechanical check or something like that and it passed - is there any cause for concern or anything or is the wiring good for another 5 to 10 years?

mikeyjames9

the cable is usually ok but there can be other issues such as the ones you've mentioned


press the test button on the rcd a few times and make sure it's working and make sure you have working smoke alarms obviously

other than that you'd have to get an inspection from a REC to check the installation

Andy From Sligo

mikeyjames9 wrote: »

.....other than that you'd have to get an inspection from a REC to check the installation

1.) If you got a RECI to check the wiring/electrics in the house - could they in fact tell you to get out of the house if its electrics or wiring is unsafe or get the ESB to cut off the electrical supply to the house?

2.) its a rented house, who would pay for the RECI to come out an inspect the house? - is the owner of the house liable for the inspection charge or is the Tenant liable because the owner could say they dont want an inspection carried out?

3.) I think there was a test before we moved in called a Electromechanical test of the house required by the PRTB - and that passed. So seeing as that passed would it mean that it would be pointless getting a RECI inspection because the Electromechanical test passed? - so it must be ok then? - or would the RECI inspection be more thorough?

Hope someone can answer these questions on here please.

brightspark

Under usual conditions PVC cable can last 50 years

http://www.basec.org.uk/News/Basec-News/Life-Expectancy-of-Cables

I expect that you were thinking of the lifespan of the old rubber insulated cables, which at this stage would be long past being safe.

Your landlord should have a periodic inspection report carried out every 5-10 years. The installation is only required to be safe (as determined by a REC), it won't have to meet current installation regulations.

SpaceTime

1970s cables are unlikely to be rubber.
You'd have a good bit of life in them yet.

Red and Black flex is very old but those colours were used in fixed wiring right into the early 1990s as far as I'm aware.

Earths to switches and roses is a relatively recent thing too.

No bonding could indicate TT earthing rather than TN.

Whatever you do, don't add bonding ! You'd need to get that checked out before assuming bonding is a good idea.

2011

Andy From Sligo wrote: »

Hi, moved into rented bungalow last June - the bungalow quite old 1970's Id say and the mains wiring is Black & Red

As I am sure you know wiring should be brown and blue.
The integrity of the PVC insulation should be fine for many, many more years.
As it was wired in the 1970s I am assuming that the insulation is PVC? If not replace ASAP

Unless the insulation has suffered form any of the following it is most likley as good as the day it was installed:
● Mechanical damage
● Rodents have gnawed at it
● UV damage
● Chemical damage

If you are concerned about it then get an electrician to carry out an insulation resistance test. This is quite quick and simple.

Most people would not replace cables just because the insulation is the wrong colour (although to comply with the regulations they should). Frequently incorrect insulation is sleeved with heat shrink of the correct colour.

- no earth going up to all ceiling roses (earth wire on living room metal ceiling lights and brass wall lamps) Black and red going to 13a sockets, no earth to any light switches

Metal lights & metal switches should be earthed.
The idea is that if a live wire were to touch the metal part the current would flow to earth and cause the protective device (MCB or fuse) to operate preventing shock risk.

If it were my home I would either install earth cabling or at least replace the lights and switches for plastic ones. Back boxes if metal should also be earthed. Remember screws for back boxes are generally exposed.

an earth wire fixed to the leg under the metal/cast iron bath but from what I can see no earth bonding under the kitchen stainless steel sink and on the cold and hot water copper tap pipes nor no earth bonding on the copper pipes in the airing cupboard/hot press.

The idea with equipotential bonding is that simultaneously accessible conductive parts are electrically connected together so that they are at the same potential. The concern is that if a metal object (such as a pipe) were to become live and a person were to touch it as well as another metal object (such as another pipe) that both objects would be at the same potential. If both objects were at different potentials (voltages) then a the person could be electrocuted as a potential difference exists across this person.

So with copper pipes bonding is important.

SpaceTime

2011 wrote: »

As I am sure you know wiring should be brown and blue.
The integrity of the PVC insulation should be fine for many, many more years.
As it was wired in the 1970s I am assuming that the insulation is PVC? If not replace ASAP

Unless the insulation has suffered form any of the following it is most likley as good as the day it was installed:
● Mechanical damage
● Rodents have gnawed at it
● UV damage
● Chemical damage

If you are concerned about it then get an electrician to carry out an insulation resistance test. This is quite quick and simple.

Most people would not replace cables just because the insulation is the wrong colour (although to comply with the regulations they should). Frequently incorrect insulation is sleeved with heat shrink of the correct colour.



Metal lights & metal switches should be earthed.
The idea is that if a live wire were to touch the metal part the current would flow to earth and cause the protective device (MCB or fuse) to operate preventing shock risk.

If it were my home I would either install earth cabling or at least replace the lights and switches for plastic ones. Back boxes if metal should also be earthed. Remember screws for back boxes are generally exposed.



The idea with equipotential bonding is that simultaneously accessible conductive parts are electrically connected together so that they are at the same potential. The concern is that if a metal object (such as a pipe) were to become live and a person were to touch it as well as another metal object (such as another pipe) that both objects would be at the same potential. If both objects were at different potentials (voltages) then a the person could be electrocuted as a potential difference exists across this person.

So with copper pipes bonding is important.

I would recommend getting the earthing system checked out fully before bonding anything to it.

Old wiring can often be earthed with a badly corroded earth rod any very little else.

That's why I wouldn't suggest connecting pipes to an unfamiliar earthing system that hasn't been checked over.

If it's safe to do so, then add bonding.

You could be adding hazards by connecting plumbing to a dodgy earthing system.

Andy From Sligo

our previous house we rented was built around 2002, and obviously Blue and brown, and copper earth (twin&Earth wiring for sockets - or separate brown, separate blue and separate green&yellow for lighting wiring) and every switch and rose had earth and there was earth bonding in the airing cupboard/hotpress copper water pipes, cant remember under the stainless steel kitchen sink, and the bath was plastic. - but this house either built in the 70's or 80's very different. I suppose different regulations at that time. The boxes behind the switches are white/cream shallow boxes from what i can see on a couple of switches ive undone and no earth to them. I suppose just spoilt with the house before being so modern, and it had loads more double sockets in the previous house. - but what is going for this house we are in even though its old is that all the cables seem to be PVC insulation so thats good then, there should be plenty more years left in them. They are definitely not rubber insulation anyways - just red and black colouring.

on an aside note the loft here was re-insulated in the loft in 2009 it says on a leaflet up there - really thick yellow fiberglass - however all the cables for lighting and sockets (its a bungalow) are right underneath the new fibreglass insulation if not under the old as well! - again I remember reading something years ago that when insulating a loft you must lay the cables above all the insulation to avoid overheating of the cables if they have high current going through them - again was that an issue with rubber insulated cables as opposed to PVC coated cables do you reckon?

Andy From Sligo

SpaceTime wrote: »

I would recommend getting the earthing system checked out fully before bonding anything to it.

Old wiring can often be earthed with a badly corroded earth rod any very little else.....

You could be adding hazards by connecting plumbing to a dodgy earthing system.

Just took a picture inside the meter box and there is an earth (not insulated) that goes into the neutral block (next to black neutral wire) under the meter part so I dont think the house just relies on an earth rod.

I also have one of these plugs that has the led lights and buzzer sound and when sockets are wired up correctly and there is earth present the corresponding lights and buzzer sounds - so I suppose the earth to the house is sound enough.

scudo2

You don't have to keep changing house every time you feck up the taps mate.

Andy From Sligo

we are in a bungalow built around 1970's/80's with Black & Red wiring but PVC insulation on them - have removed a couple of light switches and found odd things and wiring in them. for a start the back of the switch is brown bakelite and instead of the normal COM and L1 L2 for 2way switch, they are marked with A (which I presume is com) then A1 and A2 and then if its a 2gang 2way then you have a B and then B1 and then B2 stamped on the bakelite part - on one of the 1gang 1way switches there are 2 red wires and a black wire instead of the normal black and red wire or 2 reds. Now one of the reds which is permantly live is to the A (com) termainal which is right but then the red & Black wire (switched live) to the A1 terminal - why would it be wired up in such a way? - there is only one ceiling rose in the room and its all one way its not 2 way and only 1 switch in the bedroom, why the need for 3 wires? - I could understand if the wire was feeding power to another light in another room but then it would have 2 wires on the 'COM' (A) terminal not the A1 terminal. Very strange.

And then we have a switch in the lobby its a 3gang 2way switch and the end switch turns on a halogen light on a metal shed outside. Now the way that is wired up is red (com) on C terminal and then red on C1 terminal and then black on C2 terminal - again strange I dont think there is a lights switch in the shed just one in the house to turn the halogen on and off 1 way so why wire it like a 3 way switch. Can anyone throw any light (pardon the pun lol) on this way of wiring up? - have supplied pictures of the switches, they have on the back 'made in Ireland' and 5A 250v AC Only and BS 3676

mikeyjames9

Andy From Sligo wrote: »

we are in a bungalow built around 1970's/80's with Black & Red wiring but PVC insulation on them - have removed a couple of light switches and found odd things and wiring in them. for a start the back of the switch is brown bakelite and instead of the normal COM and L1 L2 for 2way switch, they are marked with A (which I presume is com) then A1 and A2 and then if its a 2gang 2way then you have a B and then B1 and then B2 stamped on the bakelite part - on one of the 1gang 1way switches there are 2 red wires and a black wire instead of the normal black and red wire or 2 reds. Now one of the reds which is permantly live is to the A (com) termainal which is right but then the red & Black wire (switched live) to the A1 terminal - why would it be wired up in such a way? - there is only one ceiling rose in the room and its all one way its not 2 way and only 1 switch in the bedroom, why the need for 3 wires? - I could understand if the wire was feeding power to another light in another room but then it would have 2 wires on the 'COM' (A) terminal not the A1 terminal. Very strange.

And then we have a switch in the lobby its a 3gang 2way switch and the end switch turns on a halogen light on a metal shed outside. Now the way that is wired up is red (com) on C terminal and then red on C1 terminal and then black on C2 terminal - again strange I dont think there is a lights switch in the shed just one in the house to turn the halogen on and off 1 way so why wire it like a 3 way switch. Can anyone throw any light (pardon the pun lol) on this way of wiring up? - have supplied pictures of the switches, they have on the back 'made in Ireland' and 5A 250v AC Only and BS 3676

the switches are probably "volex"

very common back in the day

there was little notice taken of red/black colour coding in those days

Andy From Sligo

sorry if I sound paranoid lately with all the electrical questions but ive recently seen this in the house we are renting, a Socket directly inderneath the bowl of the Stainless Steel Kitchen sink in the kitchen, am i right to be concerned at its placement seeing as water and electrics dont mix! - someone must have put it in some time for a dishwasher or something. Just wonder if theres any electricians out there that think its safe or not please to fit a socket under a sink? - Heres pic:

Deranged96

I wouldn't be comfortable with it anyway.
But then again I'm the kind of person who'll worry all day about if the stove is off or not

SpaceTime

Waste disposal I would guess.