Replacing a 47 year old CSU

[izools]

I've just bought a house built in 1965; everything is original. Well preserved, but nevertheless, has to go

Currently the property has a 60A supply and three circuits - Cooker, Ring, Lights. This is on an old wood-backed Wylex wire fuse CSU.

Now, I'm not a qualified sparkie but I want to do the remedial work myself.

As I understand it, so long as I notify the local authority under Part P, and pay the fee, I'm safe to proceed?

The property is wired with PVC T&E which appears to be in good condition so I don't want to replace any of it really; can't see a need.

I also plan to use RCBOs for each circuit. Just to make sure I know what needs to be done (not being a sparkie by trade) does this sound about right to everyone? :-

It is a TN-S supply.

Equipotential bonding to Gas & Water pipes near the CSU 16mm

(no heating / radiators at present; more equi bonding to be done by plumber when central heating gets installed)

Existing lights put on a 6A RCBO
Existing ring main put on a 32A RCBO
Existing cooker circuit put on a 32A RCBO
Radial circuit for boiler when it gets installed run via 2.5mm T&E, in trunking, to an FCU, on a 16A MCB (CSU is in the kitchen not five meters from where the boiler will be)
Radial circuit for Fridge / Freezer on a 16A MCB (trunking) - should this be an RCBO instead?
And of course a bright yellow sticker warning of the different colour standard cables in use

Does this seem sufficient and correct?

Shower will run directly from the hot water and plumber to install a sufficiently capable boiler for the job down the line.

Thanks in advance

Oh, and I forgot to mention - it is worth asking the supply be uprated to 80A and use 25mm tails?

I was thinking not as a) I'll have a gas hob, b) I won't have an electrical shower, and c) it's only a two up two down house with five rooms total inc. Kitchen and Bathroom.

 

[mikhailfaradayski]

I've just bought a house built in 1965; everything is original. Well preserved, but nevertheless, has to go

Currently the property has a 60A supply and three circuits - Cooker, Ring, Lights. This is on an old wood-backed Wylex wire fuse CSU.

Now, I'm not a qualified sparkie but I want to do the remedial work myself.

As I understand it, so long as I notify the local authority under Part P, and pay the fee, I'm safe to proceed?

paying the fee will never make anybody 'safe', only competence (and suitable tools and test equipment) will do this.

What testing equipment do you have and do you know how to use it?

What do you intend telling your council when they ask questions about compliance with regulations and certification to that effect?

The property is wired with PVC T&E which appears to be in good condition so I don't want to replace any of it really; can't see a need.

even though its already 47 years old?

Are you planning staying in this house and decorating it?

It would be a shame to see a need to change the cables 5 years down the road, don't you think?

I also plan to use RCBOs for each circuit. Just to make sure I know what needs to be done (not being a sparkie by trade) does this sound about right to everyone? :-

sounds about right, but might also be wrongish

It is a TN-S supply.

Equipotential bonding to Gas & Water pipes near the CSU 16mm

If that is true, then i doubt your opening statement of 'everything is original'

(no heating / radiators at present; more equi bonding to be done by plumber when central heating gets installed)

Why do you believe that there is a need for more of this 'equi bonding'?

Existing lights put on a 6A RCBO
Existing ring main put on a 32A RCBO
Existing cooker circuit put on a 32A RCBO
Radial circuit for boiler when it gets installed run via 2.5mm T&E, in trunking, to an FCU, on a 16A MCB (CSU is in the kitchen not five meters from where the boiler will be)

Why 2.5mm TE? why 16A mcb? Do you know the typical required rating of the fuse for the FCU in this circuit?

Radial circuit for Fridge / Freezer on a 16A MCB (trunking) - should this be an RCBO instead?

It can be either, which do you think is the most appropriate choice?

And of course a bright yellow sticker warning of the different colour standard cables in use

why not just rewire the place and save the cost of a sticker?

Does this seem sufficient and correct?

seems like the beginnings of a bodge job

Shower will run directly from the hot water and plumber to install a sufficiently capable boiler for the job down the line.

Thanks in advance

its a pleasure

Oh, and I forgot to mention - it is worth asking the supply be uprated to 80A and use 25mm tails?

please refer to your next comment

I was thinking not as a) I'll have a gas hob, b) I won't have an electrical shower, and c) it's only a two up two down house with five rooms total inc. Kitchen and Bathroom.

 

[HERTS P&D]

Get 3 quotes for a full rewire - your electrics have passed the DIY stage.

Andy

 

[izools]

paying the fee will never make anybody 'safe', only competence (and suitable tools and test equipment) will do this.

What testing equipment do you have and do you know how to use it?

Yeah, I knew this choice of words would come back on me. My correct choice would be "legal" not "safe". Would much testing need to be done other than checking Ze?

even though its already 47 years old?

Are you planning staying in this house and decorating it?

It would be a shame to see a need to change the cables 5 years down the road, don't you think?

Yes, it is in good condition. In fact it looks new. The house was owned by a lady from new and has been very well looked after. Why would the cable deteriorate more in the next five years than it has in the last 47?

I'm open to suggestion but I can't justify ripping out perfectly servicable T&E, and having to totally replaster and rewire, just to replace like for like. If you can however suggest why this would be worth the expense and time I'd happily take it on board

sounds about right, but might also be wrongish

Cool

If that is true, then i doubt your opening statement of 'everything is original'

I don't see any evidence of a separate earth supply as in the case of TT and the current earth is bonded to the sheath of the incoming cable as in the case of TN-S

Why do you believe that there is a need for more of this 'equi bonding'?

Because I will be having central heating installed which will result in a house worth of radioators and pipes that aren't there right now

Why 2.5mm TE? why 16A mcb?

Well it is a short run so I suppose 1.5MM would suffice. 16A MCB is the correct rating to use for a Radial 13A socket or radial 13A FCU is it not?

It can be either, which do you think is the most appropriate choice?

Well considering the tendancy of compressors to create an unequal load I would have thought an MCB

not just rewire the place and save the cost of a sticker?

Yeah, alright


seems like the beginnings of a bodge job

I suppose you are relating to my wanting to use the existing PVC wiring in place for the ring main and lighting circuits? But if the cable is in perfectly good condition with no signs of wear, degredation, becoming brittle, or thermal damage, why should it be replaced?

please refer to your next comment

Awesome, thanks for confirming my thoughts on the supply ampage

 

[izools]

Get 3 quotes for a full rewire - your electrics have passed the DIY stage.

Andy

Appreciate that but it isn't in the budget, besides which I have a qualified spark to help me (I say qualified, he is to 16th at any rate - he's insistent that we re-use the existing PVC which I'm in two minds about hence asking here )

 

[HERTS P&D]

Appreciate that but it isn't in the budget, besides which I have a qualified spark to help me (I say qualified, he is to 16th at any rate - he's insistent that we re-use the existing PVC which I'm in two minds about hence asking here )

If its not in the budget, then you have paid too much for the house.

Andy

 

[izools]

Appreciate that but it isn't in the budget, besides which I have a qualified spark to help me (I say qualified, he is to 16th at any rate - he's insistent that we re-use the existing PVC which I'm in two minds about hence asking here )

If its not in the budget, then you have paid too much for the house.

Andy

If all I'm going to get is sarcasm and patronisation I'll just take advice elsewhere.

Like I say, my friend who has been a spark and is educated to 16th is of the opinion that we re-use the existing wiring given that it is in mint condition and I only came here to

A) ensure the schedule of works we had seems to comply with 17th
B) get a second opinion on whether the cost, work, time, etc involved in replacing the existing wiring is justified considering it's mint condition

Anyone got a serious, useful answer?

 

[sparkwright]

It's really up to you if you completely rewire or just improve it.

There won't be enough sockets, lights in bedrooms may not be in the centre, earth sleeving may not have been used. There may not be 10 mm earth to gas, water, etc.

Some of the pvc cable of this period leaks a green slime, which can be so bad it runs through the sockets and down the walls, so look out for that.

The lighting may or may not have earth wires. Or it may be that only the switch wires do not have earths. There was a trend for this. Either way, make sure all the lighting has earth wires.

No harm to keep some or most of the existing wiring if you do remedial work and check all is well. But if practical replace it as doing it later could be difficult.

The wiring will almost certainly be in some kind of conduit in the plaster in the walls so rewiring shouldn't cause major damage.

 

[izools]

It's really up to you if you completely rewire or just improve it.

There won't be enough sockets, lights in bedrooms may not be in the centre, earth sleeving may not have been used. There may not be 10 mm earth to gas, water, etc.

Some of the pvc cable of this period leaks a green slime, which can be so bad it runs through the sockets and down the walls, so look out for that.

The lighting may or may not have earth wires. Or it may be that only the switch wires do not have earths. There was a trend for this. Either way, make sure all the lighting has earth wires.

No harm to keep some or most of the existing wiring if you do remedial work and check all is well. But if practical replace it as doing it later could be difficult.

The wiring will almost certainly be in some kind of conduit in the plaster in the walls so rewiring shouldn't cause major damage.

Thank you sparkwright, you've been really helpful.

We will check for all the things you've mentioned and replace any wiring that hasn't an earth conductor and I already have earth clamps, 16mm earth cable, and earth sheathing ready for that side of the remedial work.

Cheers for the informative advice

 

[mikhailfaradayski]

Yeah, I knew this choice of words would come back on me. My correct choice would be "legal" not "safe". Would much testing need to be done other than checking Ze?

Yes, there is more testing than just Ze.

even though its already 47 years old?

Are you planning staying in this house and decorating it?

It would be a shame to see a need to change the cables 5 years down the road, don't you think?

Yes, it is in good condition. In fact it looks new.

but you say it is 47 years old. Other than simply 'looking' at the cable, what makes you think it will remain in good condition for for the next 20-30-40 years?

Why would the cable deteriorate more in the next five years than it has in the last 47?

how much deterioration has already taken place? what if the cable installed has a working life of 50 years before it starts to fail?

I'm open to suggestion but I can't justify ripping out perfectly servicable T&E, and having to totally replaster and rewire, just to replace like for like. If you can however suggest why this would be worth the expense and time I'd happily take it on board

there are many reasons why i would replace it if i were in your position, but i don't have the time to spare to enlighten you fully. I just think that you have a golden opportunity to rewire now, it will not be easier or cheaper to do it in a few years. Also, you will probably want additional sockets/lights etc, so you will be buying cable and chasing out anyway. How much more effort and cost do you think this will involve?

sounds about right, but might also be wrongish

Cool

If that is true, then i doubt your opening statement of 'everything is original'

I don't see any evidence of a separate earth supply as in the case of TT and the current earth is bonded to the sheath of the incoming cable as in the case of TN-S

16mm bonding is not common place for a 60A TNS supply now, let alone 47 years ago-this is why i doubt one or the other statements '16mm bonding' or 'its all original'

If someone told you they had the original Mona Lisa and she was listening to an iPod, you may doubt that aswell.

Why do you believe that there is a need for more of this 'equi bonding'?

Because I will be having central heating installed which will result in a house worth of radioators and pipes that aren't there right now

Why 2.5mm TE? why 16A mcb?

Well it is a short run so I suppose 1.5MM would suffice. 16A MCB is the correct rating to use for a Radial 13A socket or radial 13A FCU is it not?

it may be correct, but it may not. There are other factors to consider (do you have any knowledge of VD or ADS?)

It can be either, which do you think is the most appropriate choice?

Well considering the tendancy of compressors to create an unequal load I would have thought an MCB

Do you intend to have a compressor fitted to your boiler? I've never seen that before

not just rewire the place and save the cost of a sticker?

Yeah, alright


seems like the beginnings of a bodge job

I suppose you are relating to my wanting to use the existing PVC wiring in place for the ring main and lighting circuits?

Yes, that, coupled with your apparent lack of knowledge.

But if the cable is in perfectly good condition with no signs of wear, degredation, becoming brittle, or thermal damage, why should it be replaced?

if you think its a good idea to do this, then go for it. IMHO its a very poor choice, but it is your choice. Crack on son!!

please refer to your next comment

Awesome, thanks for confirming my thoughts on the supply ampage

If you want to be r-c, go for it, i love it. But if you think I'm being R-C with you , your wrong. I just think that you are not making sound judgement calls.

How much do you think 1 roll of 2.5 mm TE costs? (which would probably be enough for your whole house)

Is this really too much to spend to ensure your installation stays good for the rest of your life, rather than taking a chance it might last for just another 5-10 short years.

 

[xr4x4]

Look, to cut to the chase, the only way your going to find out if your wiring is good enough to reuse, is to do an insulation test on it..this you can only do with the right tools.

End of...

your electrian should know this, if he doesn't know this, or is not prepared to check.. Alarm bells are ringing willy...

 

[Chri5]

Since you will be having floors up for ch installation why not go the whole way and do the wiring?

Both ch and a new tidy electrical system will add value to the property.

Last 2 up 2 down with bathroom and kitchen in the ground floor rear extension took me 5 days all in and material costs were £600 including metal flat plate switches and sockets. Hardly a heavy expense when most spend more than that on the TV.

False economies are exactly that. Your existing wiring will have had 47 years of use, it does degrade and ir testing will indicate so.

The contacts on 47 year old sockets and switches may have loosened, will have pitting and generally be ready for change.

On a 47 year old building I would expect that the light drops are tubed, so no need to have chases, re wiring would be achieved by pulling through new for old.

It's your choice, but since you own the place why wouldn't you want the satisfaction of knowing everything is up to date and will last for 50 years?

You will be one upset bunny if you decorate everywhere, get flooring in, revamp kitchen, bathroom and get to a pristine house level, and then the wiring starts acting up and then requires backward steps to resolve.

If a car fails it's mot and is beyond service life, would you then go a put a new engine in it?

 

[ban-all-sheds]

As I understand it, so long as I notify the local authority under Part P, and pay the fee, I'm safe to proceed?

You think that's it?

• For a circuit to supply a given load, how would you go about deciding what cable and protective device to use? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Do you know which circuits can be ring finals and which cannot, and what the advantages and disadvantages of each are? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• How do you calculate maximum demand and how can diversity be used?
  
  
• Can you correctly identify all components and connections of a circuit by method of testing or otherwise? In doing so can you identify or recognise anything wrong or dangerous with the circuit? You cannot assume that what's currently installed is OK, and you need to check it before starting work.
  
  
• Do you understand how the way in which cables are installed affects how much current they can carry? (No, you can't just copy what's there because it's going to become your responsibility and what's there might be wrong.)
  
  
• Where cables need to be joined, how should this be done / not be done and in what circumstances are different methods acceptable?
  
  
• Can you identify extraneous conductive parts, and do you know the requirements for main and supplementary bonding of them?
  
  
• Which circuits should be RCD protected?
  
  
• What about the testing that you should do on your existing installation before you change the CU, if you want to be sure of avoiding grief from new RCDs tripping?
  
  
• And what about the tests you should carry out after the installation? What sequence will you do them in and at what point will you energise the installation, and for each test do you know what is being measured, why it is important, how you would carry out the test, and with what equipment, and what sort of results you would expect to get if everything was OK?
  
  
• How do you propose to isolate the supply so that you can install the CU?
  
  
• Do you believe you are qualified to issue an Electrical Installation Certificate for the replacement?
  
  
• Are you aware that you'll need to apply for Building Regulations approval in advance, and as part of that you'll have to say how you'll ensure that your work complies with P1?
  

The property is wired with PVC T&E which appears to be in good condition so I don't want to replace any of it really; can't see a need.

So you've done things like IR testing, continuity, R1+R2, have you?


The thing is, rewiring a house, installing new CUs etc is not a trivial job, and I can assure you that it involves knowing far more than you think it does.


Please get an electrician.

 

[ban-all-sheds]

paying the fee will never make anybody 'safe', only competence (and suitable tools and test equipment) will do this.

What testing equipment do you have and do you know how to use it?

Yeah, I knew this choice of words would come back on me. My correct choice would be "legal" not "safe". Would much testing need to be done other than checking Ze?

even though its already 47 years old?

Are you planning staying in this house and decorating it?

It would be a shame to see a need to change the cables 5 years down the road, don't you think?

Yes, it is in good condition. In fact it looks new. The house was owned by a lady from new and has been very well looked after. Why would the cable deteriorate more in the next five years than it has in the last 47?

I'm open to suggestion but I can't justify ripping out perfectly servicable T&E, and having to totally replaster and rewire, just to replace like for like. If you can however suggest why this would be worth the expense and time I'd happily take it on board

sounds about right, but might also be wrongish

Cool

If that is true, then i doubt your opening statement of 'everything is original'

I don't see any evidence of a separate earth supply as in the case of TT and the current earth is bonded to the sheath of the incoming cable as in the case of TN-S

Why do you believe that there is a need for more of this 'equi bonding'?

Because I will be having central heating installed which will result in a house worth of radioators and pipes that aren't there right now

Why 2.5mm TE? why 16A mcb?

Well it is a short run so I suppose 1.5MM would suffice. 16A MCB is the correct rating to use for a Radial 13A socket or radial 13A FCU is it not?

It can be either, which do you think is the most appropriate choice?

Well considering the tendancy of compressors to create an unequal load I would have thought an MCB

not just rewire the place and save the cost of a sticker?

Yeah, alright


seems like the beginnings of a bodge job

I suppose you are relating to my wanting to use the existing PVC wiring in place for the ring main and lighting circuits? But if the cable is in perfectly good condition with no signs of wear, degredation, becoming brittle, or thermal damage, why should it be replaced?

please refer to your next comment

Awesome, thanks for confirming my thoughts on the supply ampage

i.e. basically a whole lump of text which shows that he doesn't even have the brains to be able to cope with constructing posts on an advice forum.

iztools - go an stand in front of a mirror, and in your best Ali G impression say "Is it because I is a dork?".

And imagine the answer "Yes".

Please get an electrician.

 

[ericmark]

I will admit it says on the Part P document that once you pay your fee then the LABC become responsible for site safety. But of course the LABC can lay down conditions to ensure that the site is safe and in real terms those conditions mean unless your a commercial electrician who has all the skills but is just not a member of a scheme it is unlikely that they will allow you to proceed.

Even then likely your in for a fight. My son and I took over a job of building a wet room when the builder ran off into the Welsh hills. We had assumed it was all registered with the LABC so went to see them over taking over the work. The building bit was OK but they wanted us to get a scheme registered electrician and since both my son and I are qualified there was no way that was going to happen. Because it was disabled work there was no fee involved.

Question one is how are you going to test it. Answer is use that 16th Edition (as it was then) test set you can see on the floor. Then it was do you know how to use it. My son says yes of course do you want to see my C&G 2391. Oh comes the reply I don't think that's good enough. My son then says my dads got a degree in electrical and electronic engineering at which point he backed down and allowed us to proceed as long as I did the testing.

Clearly the council inspector did not have a clue what a C&G 2391 was as it was far more relevant than my degree. I also had the certificate but the inspector did not know that.

So if two fully qualified electricians struggle to get the council to allow them to proceed what do you think your chances are?