Rewire

[rjwbrown]

After a bit of advice/clarification re 18[SUP]th[/SUP] edition of the regulation.
Firstly a bit of background, having a lot of work done on a 70's bungalow for my mother in law, altering the layout, lounge/dinner to a kitchen/dinner with separate lounge, new bath room, new external oil boiler and included a complete rewire.
There have been a few points raised by the electrician of which I found a bit strange.
He wanted to move the meter and I said no as it is fine where it is and I did not want to fall foul of any of the supply company regulations.
I wanted one double pole switch for the oven (Total connected load 3.68KW) and the hob (Total connected load 2.99KW) and he wanted two, both are well within 2 meters of the switch position I had in mind. The reasoning here is glass splash backs and the less holes the better a each hole adds to the cost.

Earth bonding to the water main he wanted the stop cock under the kitchen sink as he said “that’s where they go” and I have opted for a remote (Surestop) one which is plastic and the incoming pipe is plastic, and only picks up copper under the bathroom floor. The reason for picking a remote one is that in the event of a leak an elderly person would have problems with the older brass tap never mind getting to it. Does this earth connection need to be assessable? It is going to be under the floor in an area that is not readily accessible as it will be tiled.
The new main CU is having all RCBOs fitted so I’m thinking that any supplementary bonding is only precautionary rather than a requirement.

Garage supply in armored cable not a problem there and I was going to use a plastic garage CU but he said he would have a problem with the termination but I thought what’s wrong with a metal box along side the CU for the termination of the armored cable.

Any comments welcome good or bad and have I missed anything I need to be aware of.

Rob

 

[telectrix]

there would be if you got them to fabricate 135 bends in 4" galv. trunking.

 

[stratplus]

If its being rewired wouldn't it be having a new c/u in which case why use all RCBO's? Surely a RCD protected board will be used??

 

[rjwbrown]

Thank you all for your comments, where to start with a reply?

The CU with RCBOs was my idea not his he wanted to fit a split CU with a RCD but you lose 2 ways when you spit the CU and space is a problem OK for 12 way, 16 way just and anything larger would require a change to the meter cupboard.

Bonding the water pipe is a problem area as I can not have the join plastic to metal in the kichen so stop cock under the kitchen sink is out.
Reading the regulations

Where practicable the connection to the gas, water, oil, etc., service should be
within 600 mm of the service meter, or at the point of entry to the building if
the service meter is external and must be on the consumer's side before any
branch pipework and after any insulating section in the service.

There must be some lattitude here other wise why say "practicable" and "should" does not mean has to be or am I reading this incorrectly.
I could understand there being issues if compession joints or screw threaded joints are used on metal pipe work as this could introduce a path of higher resistance but soldered copper pipe work should not present such issues as it should be a good path with very little electrical resistance. That does assume they joints are soldered correctly but if they were not they would leak.

It may be possible to have the bond in the bathroom as the basin is on a cabinet and all the taps are mains fed incuding the hot water. Will need to look at distance from join to cabinet but it will not be anywhere close to the plastic stop cock just close to where it goes from plastic to metal.

May be I should have done all the water pipes incuding the heating in plastic then the problem would not arise

Will be using metal CU's as that is not a problem or going to cost an arm and a leg and should make a tidier job.

As for leaving the electrician alone to make decisions on what goes where, not a chance as I know where the sockets, switches need to go, that does assume the positions meet the current regulations or there is another reason for them to be postioned else where.

I have good understanding of electrics although not quailfied as such and had I been younger would have done the work myself and just had it signed off at the end.

BTW: I am not looking over his shoulder as the job is 160miles away so can only get on site about once a week and just because someone is quailified does not mean they can not make a mistake, we all do but try our best not to.

 

[GLENNSPARK]

how big is this house?

 

[LlandrilloSpark]

Why are you bonding an incoming plastic service ??????

 

[rjwbrown]

Three bed bungalow aprox 77 sq meters floor area.

Not bonding to plastic as that to me would be a pointless excercise but to the metal pipe work after the plastic.

 

[telectrix]

as above. if the incoming water service is in plastic, then the spark should IR test from the MET to exposed copper pipework. if the reading is >22k ohms, then it should not be bonded. as for your sockets and switches, you determine at what height you want them. this silly 450mm - 1200mm rule is a building reg. applicable to new builds only, and not to rewires.

 

[GLENNSPARK]

Three bed bungalow aprox 77 sq meters floor area.

Not bonding to plastic as that to me would be a pointless excercise but to the metal pipe work after the plastic.

split load hi-integrity c/u would be an option here....less cost and perfectly compliant....whats the earthing arrangements?

 

[telectrix]

if the OP wants RCBOsd, then it's his choice. it's usually the other way round where a customer won't pay the extra. if cost is not an issue, then RCBOs every time where possible. less room taken up in the CU, and dual RCD boards are a compromise anyway.

 

[GLENNSPARK]

if the OP wants RCBOsd, then it's his choice. it's usually the other way round where a customer won't pay the extra. if cost is not an issue, then RCBOs every time where possible. less room taken up in the CU, and dual RCD boards are a compromise anyway.

indeed Tel....just an option for em to think about...

 

[rjwbrown]

Do not believe any checks were done on the resitance of the water services but that said the external boiler may well introduce some earth potential.
Height and position of sockets/switches within the 450/1200mm rule is not a problem as they are is some respects a better position for the elderly.


Not sure of the incoming supply as I'm 160miles away so can not check at this moment in time but will take a good look on my next vist.
As for a split CU as aposed to all RCBOs then the cost was not a major consideration, if my understanding is correct then RCBOs are the better choice if cost is ignored.

 

[telectrix]

the boiler will be bonded anyway through the gas/oil service. and RCBOs are definitely the best option. unless they're protek, of course.

 

[LlandrilloSpark]

Going to have to say this...

Threads like this make my blood boil, we are not "Sparkwatch", yes we can answer queries from homeowners ect but we are not here to cast judgment on a fellow sparks work via a third party, especially one who talks like he has had his head in BS7671.

Not impressed

 

[GLENNSPARK]

Going to have to say this...

Threads like this make my blood boil, we are not "Sparkwatch", yes we can answer queries from homeowners ect but we are not here to cast judgment on a fellow sparks work via a third party, especially one who talks like he has had his head in BS7671.

Not impressed

what?

 

[vjsmarwick]

Not only will the outside boiler be earthed via the service pipe oil/gas but also via the supply cable to the electrics of it but your plastic cu in the garage is the way I would go 100% of the time no rusting due to dampness and like engineer I would have no problem terminating the steel wire direct in to it and use earth tag for the earthing of the armouring. There are many ways to do most electrical work so although your spark may be right with what he says there is also nothing wrong with what you want and it's you with the money as for isolators in the inside of cabinets it would not be my choice as mostly become inaccessible or renders some if the space in them as useless and the regs say they Should be accessible. We all have our own ways of doing things and all do what we think is best it does not mean we are right or wrong just individuals