House wiring and building regs

[Sheaf]

Hi, I'm not sure if anyone in here can help...

I'm planning on doing a load of work to my house, extensions side and rear. We'll need planning permission and building regs approval/inspections.

I'm getting the shell done and part of the inside plastered, however plan to do the electrics and plumbing myself, along with other interior stuff (stud walls, architrave flooring etc).

My question relates to the wiring. I'll be wiring with reference to bs7671, as situated by building regs. I'm confident that I will be able to do this and conform to the rules set out (although I'm not convinced most installations do conform after reading various parts).
The planning portal website clearly states that anyone can do this, you just need it improved and inspected by the local planning authority.
However, do you need to document everything you do in order to get it signed off? Do I need to sketch what I plan to do and get it approved in advance or can they just come and inspect it after??

Doing it myself will save maybe £2k so its worth the effort, but I'm not sure how an uncertified person goes about getting it done.
Obviously registered electricians are on the competent persons scheme so just self certify.

Any ideas? Anyone done this? If I need to draw it up in advance that's fine, I just done want to wait until its all done and then find I can't get it approved due to nothing being visible.


Cheers

Alex

[1234dist]

Pretty sure the electrics are fine if you have them inspected by a spark once you are done you can use that in your evidence to the planner.

[Sheaf]

Incidentally, I'm aware that some stuff basically says you can't do it yourself. Such as this

However this basically says you can't do it yourself if you get it approved.

I've got a feeling ill need to phone my local planning authority but just wondering if anyone else went through this.

[Sheaf]

Pretty sure the electrics are fine if you have them inspected by a spark once you are done you can use that in your evidence to the planner.

Yeah, I've just been told most sparkies don't want to approve other people's work.

[1234dist]

obviously, they don't get their £50ph then.

[vinny19791]

I see what you did there

Clever

[Sneekyparrot]

Hi M8,
Any electrical addition's or modifications to the house circuits will require a Part P testing / certification by a Qualified electrician. It's not a case of getting £50 out of it as mentioned whoever signs this off is accepting resposiblity for the installation, putting there name and number to it. Building control will want to see the Part P Cert.
I have seen too many bothched installs by people who have a vague idea what they are doing some of which ended in fire's and live walls

P.

[E_T_V]

As above. You can do the work yourself but it needs to be inspected by a qualified sparky once complete. Note that they may well want to see it before everything in the house is complete so they can get access to various stuff.

[1234dist]

i meant per hour, have updated original post

[Sneekyparrot]

i meant per hour, have updated original post

No worries bud.

man love a job where i could earn 50 an hr

P.

[Sheaf]

Hi M8,
Any electrical addition's or modifications to the house circuits will require a Part P testing / certification by a Qualified electrician. It's not a case of getting £50 out of it as mentioned whoever signs this off is accepting resposiblity for the installation, putting there name and number to it. Building control will want to see the Part P Cert.
I have seen too many bothched installs by people who have a vague idea what they are doing some of which ended in fire's and live walls

P.

Yeah, i have a copy of Part P as well as BS7616:2008. It's making some loooong reading.

My main issue is just making sure that whoever I need to inspect (be that building control or a certified competent electrician) I want to ensure they can sign it off and don't say they can't see everything etc.

I'm not worried about doing it safely though, I suspect I'll be more likely to abide by the rules than if I paid somebody!
My job involves electrical installations and design for MOD equipment, so domestic stuff largely just seems like common sense in comparison.

My house was rewired in 2008 by the builder who did it up in that year and tbh I'm not overly impressed by how his sparky did the wiring.... cables pulled tight with no slack, NO RCD/RCBO on lighting (yet wiring install doesn't conform with requirements for this), wiring installed in top notches on joists, not away from surface as required. Both up and down circuits are radials rather than rings, which just seems cheap (I'm extending them to rings as I extend those circuits). The consumer unit was a mess, just bundles of cables with zero consideration for maintenance.

The rules are there for a reason and the requirements to have it checked are too, I have no intention of bodging it, far from it, I'll more likely be OTT perfectionist. Just need to make sure it's signed off.

[Sheaf]

The more I read, the more unclear it gets.

It's almost circular, one thing leads back to another.

My current plan A:

- Design circuits and installation. Submit to LBA with architectural plans
- LBA come and inspect at first fix to ensure the install is in accordance with the regs
- Get independent electrician to test and issue PIR (Periodic Inspection Report) which verifies the integrity of the cabling/terminations.

I'm planning on phoning the LBA to check this plan is ok.

Plan B is to find an independent electrician to inspect the install at first fix and then test and sign off IF I can find one who will. This would be easier and may be cheaper depending on building application/inspection costs.


Bit of a pain it seems.

[BlueRover]

I would be inclined to have a sparky install a new consumer unit for the whole house prior to building work and get him to fit one which had redundant connections, say a 15 way instead of a 8. That way you can connect extra wiring circuits without having to have the house disconnected from the mains. Wiring circuits are simple if you follow safety rules and use the correct cabling, rcd and sockets. Pay for well branded, quality equipment and you have a good startting point.
I assisted an electrician who rewired the lighting circuits on the house as part of mortgage conditions and I was surprised how little work was done for the money.

[Marty]

I would run the wiring in and get a sparky to wire it up that way they will be happy to put there name to it and the donkey work of threading it all through is done

[Sheaf]

I would be inclined to have a sparky install a new consumer unit for the whole house prior to building work and get him to fit one which had redundant connections, say a 15 way instead of a 8. That way you can connect extra wiring circuits without having to have the house disconnected from the mains.

My plan was to add a second consumer unit in the garage we're building, largely because it'll be more accessible than the existing unit under the stairs, but easy to connect as it's just the other side of the wall.
Access to the existing unit will be much more time consuming and annoying.

Means the existing 32A kitchen ring will become a 20A utility room radial and the new unit will have:
32A New Kitchen ring
6A Kitchen lights
45A Kitchen oven/hob
20A Garage radial
32A garage cooker connection (for arc welder) non RCD protected
6A Garage lights
20A new bedroom radial

I might run the bedroom lights off a 5A FCU from the bedroom circuit, might put in another circuit, just seems a bit ott for 2 lights and an extractor fan.

As the garage will be below the new bedroom and adjacent to the new kitchen, makes sense to stick a new CU in to feed the new circuits.

Plan is to get a 100A DP isolator between the metre and the existing CU with twin outputs as you need to have a single point of isolation foot ALL circuits.

[Sheaf]

Well, after some more investigation, I found this -

http://www.electrical-testing.co.uk/p/a ... -affect-me


Section 3.8 to 3.12 describe getting it certified by a building authority.

This agrees with my LBA which I called up and asked about it. Sounds like the inspection/test fees mount up a bit that way. Basically, looks like I'm probably looking at £500 fees. However That is still maybe a £1000+ saving even with materials costs considered.

If I can find a more friendly electrician, that's a better option, but I can't count on it.
I'd have thought though that somebody would see it as easy money for an inspection visit and a testing visit, no actual labour involved an a couple of hundred quid in their pocket.

[1234dist]

Problem is, by signing it of they are as good as saying yes i did this work and the liability thus associated.

[Sheaf]

This is true, however if they can see all the wiring to inspect it AND they can test it, surely there shouldn't be a problem with that?

I mean, if you buy/sell a house you can get a sparky in to test and issue a cert for the sale...
The council comes and approves other aspect of building work and signs them off.
Structural surveyors assess and sign off existing buildings all the time.
Hell, an MOT tester assesses the safety of a vehicle which travels at extremely dangerous speeds and issues a cert in 30-40 minutes.
An NDT tester will test somebody elses welds and sign them off.
At work we pressure test and electrically test items and it's general practice that the person who tests it is NOT the person who's assembled it, because you don't see your own errors.

I don't think it's unreasonable for somebody to inspect/test it. At the end of the day, it's still only saying it's safe that day as once they go anyone could do anything to it so complete responsibility can't be done completely.

[Quiche81]

BS7671 is on the 3rd amendmant at the moment (Just to add), also, it will be a horror to try and understand it.
The OSG (On Site guide) is by far a clearer option.

Indeed you will have a lot of trouble getting a sparky to simply sign it off, that said, its not outside the realms
of possibility to talk to them and explain what you'd like to do, not all sparks are monsters, you may be able to
work something out.

The 17th hit the shelves back in about 2008 IIRC, so techinically a 16th edition board may have been applicable
at the time (Split load, not dual RCDs)

Buying, selling and installations certs are very different. Periodic inspections are more for buying and selling, its
kinda like the MOT. Installations certs (EIC's) are issued for new works / circuits etc. Minor works for just that.

[Quiche81]

This is true, however if they can see all the wiring to inspect it AND they can test it, surely there shouldn't be a problem with that?

LABC inspectors can't test work, when they inspect work i've completed, they will usually record the cert number and
my registration body, and believe it or not, thats about it. They may ask the odd question about fire rating of downlights
and energy efficiency as they come under other building Reg's, but thats about it.

[Quiche81]

Plan is to get a 100A DP isolator between the metre and the existing CU with twin outputs as you need to have a single point of isolation foot ALL circuits.

If a Meter tail run is going to exceed 3 Meters, Metering 'may' prefer a fused isolator btw.

You can have a standard DP isolator into a service connector block btw, or run your second fusebox as a submain from
the main consumer unit.

Also, new fuseboxes have to be Amendmant 3 compliant, this update to BS7671 relates mostly to combustable materials
inside fuseboxes.

[Sneekyparrot]

Tbh I would be more inclined to fit rcbo's to each circuit minus the welding one. Doing this will mean If u trip one then it won't take the rest of the circuits out. Bit more expensive but I think cost is worth it [emoji1]

[Sheaf]

The 17th hit the shelves back in about 2008 IIRC, so techinically a 16th edition board may have been applicable
at the time (Split load, not dual RCDs)

Yeah, turns out they did it in 2005 not 2008, I misremembered the paperwork id seen. Makes more sense.

The meter tails will be well under 3m, it'll literally be on the other side of the wall so will just depend on the height its mounted. Probably back to back purely to minimise the length tbh.

It seems my problem may be solved, spoke to our builder and he's confident he knows a sparky who would be willing to inspect, correct if required (or point out and problems and let me fix it) and test/sign off. Result.


Interestingly, I ended up reading about ways of doing various kitchen wiring.... Seems with all these regs there's still plenty that people are still unsure about and leave to their own judgement.

I was trying to figure out what isolation you have to have for appliances.... I know SFCUs are common above worktops which feed sockets under, however lots of people don't like them because of the looks and also because you end up fusing appliances twice which isn't great practice.
So, some people just have sockets in cupboards but that's a debate about whether a cupboard is part of the building structure and the void if a safe zone or not.
Then, lots of people use 20A dp switches above the worktops, in fact the grid type are perfect for it and come labeled too.... But there's a whole debate as to whether you can put them in a 32a ring!
Some say no as it's only rated at 20A, however others say it's fine as you are only using the supply side as a terminal and not actually passing 32A through the switch contact.

I think my logic would agree with the latter on the basis that 2.5mm cable is no good for 32a anyway and the whole basis of the ring is it splits the load around, so you'll never pass more than 16A through the terminal or 13A through the switch, assuming a single socket spur.

BUT, as I say, there's no definitive answer it seems and its all down to judgement of the installer.... It would help if the manufacturers just rated the terminals separately.

I also read that apparently if the CU is accessible that's a sufficient means of isolation anyway, lol.

I'm worryingly finding it all quite interesting.

[Quiche81]

The 17th hit the shelves back in about 2008 IIRC, so techinically a 16th edition board may have been applicable
at the time (Split load, not dual RCDs)

Yeah, turns out they did it in 2005 not 2008, I misremembered the paperwork id seen. Makes more sense.

The meter tails will be well under 3m, it'll literally be on the other side of the wall so will just depend on the height its mounted. Probably back to back purely to minimise the length tbh.

It seems my problem may be solved, spoke to our builder and he's confident he knows a sparky who would be willing to inspect, correct if required (or point out and problems and let me fix it) and test/sign off. Result.


Interestingly, I ended up reading about ways of doing various kitchen wiring.... Seems with all these regs there's still plenty that people are still unsure about and leave to their own judgement.

I was trying to figure out what isolation you have to have for appliances.... I know SFCUs are common above worktops which feed sockets under, however lots of people don't like them because of the looks and also because you end up fusing appliances twice which isn't great practice.
So, some people just have sockets in cupboards but that's a debate about whether a cupboard is part of the building structure and the void if a safe zone or not.
Then, lots of people use 20A dp switches above the worktops, in fact the grid type are perfect for it and come labeled too.... But there's a whole debate as to whether you can put them in a 32a ring!
Some say no as it's only rated at 20A, however others say it's fine as you are only using the supply side as a terminal and not actually passing 32A through the switch contact.

I think my logic would agree with the latter on the basis that 2.5mm cable is no good for 32a anyway and the whole basis of the ring is it splits the load around, so you'll never pass more than 16A through the terminal or 13A through the switch, assuming a single socket spur.

BUT, as I say, there's no definitive answer it seems and its all down to judgement of the installer.... It would help if the manufacturers just rated the terminals separately.

I also read that apparently if the CU is accessible that's a sufficient means of isolation anyway, lol.

I'm worryingly finding it all quite interesting.

Switched spurs at worktop level often have flex outlets (Appliance plates) behind the appliance to save on doubling up on fuses, this
did kick off an interesting debate some years back with warrenty issues though (Removing moulded plugs etc) so most stuck with an
unswitched outlet instead, while having two fuses seems a bit daft, when you think about it, how often does a fuse pop, and if it does
then there's usually a good reason for it anyway so nto really something to worry about.

Outlets in cupboards is very normal, and yes you can put them in a cupboard with a sink in it, people often go 'Ooooooo but what if the
sink leaks etc' But why should it ? and if it did, its a plumbing issue, not an electrical one iyswim.

Safe zone's really apply more for 'buried' cables more than cables clipped behind cabinets directly to the wall.

If you're builder has found a helpfull sparky, just liase with him and keep each other updated on how things are progressing and everything
will turn out fine

[Sheaf]

What's your take on the 20A grid DP isolators (rather than switched spurs)?
Like this

Stick them in the 32A ring, add them in after a hidden fused spur or run a separate 20A radial for appliances?

I'm not actually 100% sure they're actually isolators anyway mind rather than just switches (I don't think they state a 3mm gap).

I did read something about the appliance plates and warranties. Yeah, I think I'd rather just have 2 fuses myself as when you want to pull a washing machine out, it's enough of a pain with feed and drain hoses let alone having a fixed flex which probably isn't quite long enough and you have to unwire to get the machine to a suitable location...

[Quiche81]

What's your take on the 20A grid DP isolators (rather than switched spurs)?
Like this

Stick them in the 32A ring, add them in after a hidden fused spur or run a separate 20A radial for appliances?

I'm not actually 100% sure they're actually isolators anyway mind rather than just switches (I don't think they state a 3mm gap).

I did read something about the appliance plates and warranties. Yeah, I think I'd rather just have 2 fuses myself as when you want to pull a washing machine out, it's enough of a pain with feed and drain hoses let alone having a fixed flex which probably isn't quite long enough and you have to unwire to get the machine to a suitable location...

The Grid switch arrangment is fine, there are plenty of varying makes but all do the same job.

They're suitable forms of isolation for appliances, the 3mm contact gap is more commently required on
higher load appliances where energising or de-energising may be done under higher loads, its an ark thing

[Sheaf]

We're getting pedantic, but I thought an isolator was a device which renders a circuit safe by isolation, where isolation is defined as being 3mm distance for 240V.

In other words, a circuit which is isolated can be worked on. It is safe and will 100% not see any potential.

The switches in a standard socket however are switches, not isolators. Any device plugged in and switched off is not safe to work on. It must be either unplugged or isolated in some other adequate manner such as a switch disconnector.

The above has been drummed into me for the last 10 years by our electrical duty holder at work (I do deal with electrics with work but not domestic).

Incidentally, we did actually have an MK switched socket fail a while ago at work, proving the point that it's not adequate to trust with your life but is ok for functional switching.

[Quiche81]

We're getting pedantic, but I thought an isolator was a device which renders a circuit safe by isolation, where isolation is defined as being 3mm distance for 240V.

In other words, a circuit which is isolated can be worked on. It is safe and will 100% not see any potential.

The switches in a standard socket however are switches, not isolators. Any device plugged in and switched off is not safe to work on. It must be either unplugged or isolated in some other adequate manner such as a switch disconnector.

The above has been drummed into me for the last 10 years by our electrical duty holder at work (I do deal with electrics with work but not domestic).

Incidentally, we did actually have an MK switched socket fail a while ago at work, proving the point that it's not adequate to trust with your life but is ok for functional switching.

lol.. Not pedantic at all, its a serious thing in the electricity world.

Electrical Isolation is to remove electrical energy from a circuit, if its DP then obviously it disconnects Neutral also.

Most socket outlets are single pole switches and only isolate the Line conductor, some are DP and disconnect both.

Now, The fuseways or MCB's in your fusebox only disconnect the Line conductor, but I'd bet you'd work on the circuit with
only the fuse or MCB removed, but would you with say a switched spur with only the switch off ?

Ultimately the incomer turned off is the safest way, On assesments, we have to perform 'Safe isolation' and prove the
power is off, not just rely on the fact the incomer is in the off position, you also have to have a 'proving unit' to prove
your contact indicator that you checked the circuit was dead with, actually works lol..

The bottom line is, as I suspect you have been told a squillion times in your line of work.. Dont rely on it being a dead
circuit, prove its a dead circuit, I have MCB lockoffs which in the domestic arena you dont really use, but I suspect
you do due to location and people that like to fiddle

As a kinda odd thing, there seems to be this thing nowadays (As a safety feature) about breaking the neutral last
but reconnecting it first, while I sort of see the benefit, it happens so amazingly quickly I dont see the point iyswim.

[Sheaf]

No, I wouldn't work on something with just a switched spur off.... As said, I've no idea about whether that switch has good enough isolation for me to trust. If either turn off the MCB or remove the fuse from the spur. Contacts can fail on switches, plus they're prone to people turning then on without thinking!
I wouldnt trust a relay to isolate either. I would trust a contactor if the coil was isolated though....

DP isolation or switching seems a little redundant in a lot of domestic electrics as the neutral is ultimately earthed back at the substation (as 230v is generated from 1phase of the 415 3ph supply and earth) i think so although it can have residual voltage (which tbf is enough to trip an RCD when shorted to earth) it doesn't generally have enough to shock.
I'm guessing dp plays more of a role if you're fed from a generator and live and neutral are both floating?

At work we use proving dead testers which can print they work afterwards, rather than a fluke multimeter as they can mislead. Not much of our stuff is 240v though as its naval equipment and usually floating voltages.

So back to the grid switches, it should be considered fine to use them as effectively spur boxes then, just put the supply sides in the ring and feed single sockets off the load side? Only 13a can go through the switch due to the downstream fuse in the plug but the supply terminal will be part of the ring. I'll likely use MK ones.
Seems a lot less messy than the alternatives which involved multiple fused spurs in cupboards.

Alex

[Quiche81]

So back to the grid switches, it should be considered fine to use them as effectively spur boxes then, just put the supply sides in the ring and feed single sockets off the load side? Only 13a can go through the switch due to the downstream fuse in the plug but the supply terminal will be part of the ring. I'll likely use MK ones.
Seems a lot less messy than the alternatives which involved multiple fused spurs in cupboards.

Alex

Exactly that, as long as they feed a single or a fuse spur (Switched or unswitched), as you've allready said then that'll be fine.

[Sheaf]

Ok, one more question, one which I can't get my head around.

I'm planning on having a double oven, 4 burner gas hob, but also a 2 burner induction hob.
The double oven will probably pull in the region of 26-30 amps max. The induction of hob will be around 16A max.
Can I put these on a single cooker isolator?

You can obviously connector up 2 loads to a CCU, however it'll be on a 40A/50A MCB

This will protect the cable for the oven but I'm guessing the terminals on a 2 burner hob will be smaller and may need as small as 2.5mm² cable. One I saw comes with 1.5mm² cable attached?!?!

Obviously that cable wouldn't be protected... so is no good.

Can you get 20A fuse boxes, so I can go MCB>DP Cooker Isolator>CCU> then split to oven and to 20A fuse to hob?

Only other way I can think is a seperate MCB with 2.5mm² all the way.

[Quiche81]

Ok, one more question, one which I can't get my head around.

I'm planning on having a double oven, 4 burner gas hob, but also a 2 burner induction hob.
The double oven will probably pull in the region of 26-30 amps max. The induction of hob will be around 16A max.
Can I put these on a single cooker isolator?

You can obviously connector up 2 loads to a CCU, however it'll be on a 40A/50A MCB

This will protect the cable for the oven but I'm guessing the terminals on a 2 burner hob will be smaller and may need as small as 2.5mm² cable. One I saw comes with 1.5mm² cable attached?!?!

Obviously that cable wouldn't be protected... so is no good.

Can you get 20A fuse boxes, so I can go MCB>DP Cooker Isolator>CCU> then split to oven and to 20A fuse to hob?

Only other way I can think is a seperate MCB with 2.5mm² all the way.

Ok, A couple of ways you can deal with this but firstly, most appliances will specify a fuse size, its often
inside the door of an appliance along with its maximum load in kW, you should fit seperate isolators for these
appliances.
The induction is most likely going to recommend a 16A fuse, the oven a 32A, but worth a check.
The induction at that load is also likely to be prewired and the oven not so.

Option 1 is to obviously run a supply for each with a cooker isolator and a 20A isolator for the induction
with the oven being in 6mm 2+e and the induction with 2.5mm 2+e with a 32 and a 16Mcb respectively.

Or, Option 2
Run a single 10mm to the kitchen, install a small 2way fuse box. Fit a 40A in the main board and in the
sub board, fit a 32A and 16A

"IF" a 6mm exists already and its not buried cable, i.e. its clipped in freespace, you can use this with the
above method.

Just to add to the confusion, you could apply some 'diversity' here which may reduce the total kW though
i'd probably not bother.

I'd chose the option that is easiest for you to do, they both acheive the same result so neither is better than
the other, funny enough, I did a kitchen today with option 2 but in 6mm on a 32A supply MCB (Was for x2 16A)
to supply 2 pyrolitic Bosch ovens.

[Sheaf]

I suspect I'll probably go for option 2....

I'm guessing the appliances don't have internal fuses then? I was always told the fuse/mcb was to protect the supply cable, not the device. I suppose it depends what they state in the instructions.

I was wondering about just doing 40A at the CU and then just adding a 20A MCB locally for the hob, with the oven covered by the 40A. But as you say, it depends on the appliance and for sake of a fiver I guess adding both is worth it.
It saves running 2 cables from the main board or having 2 local DP isolators anyway and the hob will likely come later so can be added then.

Getting there, I think most of the circuits are planned out now. Sooooo many cables.

[Quiche81]

I'm guessing the appliances don't have internal fuses then? I was always told the fuse/mcb was to protect the supply cable, not the device. I suppose it depends what they state in the instructions.
.

Thats correct, fuses only protect the cables, the appliances wont be internally fused.

Your plan sounds fine, but I reckon a 32 and a 16 would be ok in your mini fusebox, without seeing
the spec for the appliances I couldn't say, normally I'd take the kW and devide it by 230 for an
indication of the maximum load of each appliance.

Sounds to me like everything is coming together

[Sheaf]

Yeah, it is, although due to the nature of the new floorplan, the kitchen, dining room and utility will all have multiple doors into/out of each one so placement of switches is going to take a bit of thinking about.

Plus need to figure out the AV side, largely where speaker cables are going as want to put in either ceiling speakers or high bookshelf speakers and link them to multiple sources.

And I'm also trying to figure out if the boiler can start where it is or not, which depends on whether I can go extend the flue about 3m....

Fun times, although I should hopefully get what I want and not spend years wishing I'd considered more when doing it.


One thing I'm considering with the electrics though is combining some circuits, such as kitchen lights with the bedroom lights, as it seems excessive to have whole seperate circuits for 1 or 2 lights, or a single array of downlights. Are there any rules about this?
I know it would obviously be a bad idea to have !lights and power on the same circuit (spurred off) for the same room ASA failing device would plunge you into darkness but are say light circuits on different floors OK to combine?