ReWire to a 3 bed house and an outhouse. Comments plz.

[racket]

Thanks Qedelec, I'm no sparky so i stand corrected.

 

[ban-all-sheds]

I still have a bad feeling about all of this....

 

[YCWB]

I was originally going to do the outhouse in 6mm cable but 2 people have told me to just use 2.5 and they are electricians. i thought 4mm would probably be enough but 6 would be better. im thinking 32A maybe better and if needs be put in a 40A at a later date.

im not sure on running in a seperate feed for the freezer? is this common place? i know the kitchen as a whole can be on a seperate ring but as only the living room and dining room will be on the same ring i didnt see this as much of a problem. the upstairs ring will be on a seperate one. would it be better to have 3 rings, one upstairs, one downstairs and one for the kitchen? or would it be better design to use one ring for the kitchen and one for the rest of the house? i know this isnt set in stone and im sure a few people on here will have different views.

Still not decided on best way to do the outhouse, probably leaning towards running 6m SWA straight from the CU right into the outhouse and then just a few sockets off that and one light. the RCD in the house will protect the downstairs ring and the outhouse. it could also do the upstairs ring but as none of the sockets are likely to be used for equipment outside then there is no special need.

 

[SamySnake]

I was originally going to do the outhouse in 6mm cable but 2 people have told me to just use 2.5 and they are electricians. i thought 4mm would probably be enough but 6 would be better. im thinking 32A maybe better and if needs be put in a 40A at a later date.

The mcb is selected for the sole purpose of protecting the cable. Select the cable by calculating your design current, then look in your OSG and select a suitable mcb to protect that cable.

 

[Pensdown]

Who is going to be doing the work?

This thread has gone off on a tangent. As BAS asked early on, who is going to do the works as it will need to be certified, either by a Part P contractor or building control. This sounds like a major project and without doubt needs to be done properly.

If you want to do the work yourself, and judging by the quality of your questions that may be possible. I would suggest that you contact a local PP approved contractor, pay them to design the installation, maybe ask them to source the materials (you may get a better product for less money) pay them to inspect the work at first fix and pay them to test and issue the correct documentation on completion.

The end result will be a good installation that conforms to all current regs and is signed off in the correct way. When you go to sell your property, this will add value.

I know of more and more contractors that are offering this service for this type of project and it works very well. You do the donkey work, and they do the technical work, everyones happy

 

[ban-all-sheds]

im not sure on running in a seperate feed for the freezer? is this common place? i know the kitchen as a whole can be on a seperate ring but as only the living room and dining room will be on the same ring i didnt see this as much of a problem.

As explained before, the point of a separate circuit is not to deal with loading problems, it is to get the F/F off of an RCD protected socket circuit.

the upstairs ring will be on a seperate one. would it be better to have 3 rings, one upstairs, one downstairs and one for the kitchen? or would it be better design to use one ring for the kitchen and one for the rest of the house? i know this isnt set in stone and im sure a few people on here will have different views.

IMO you should be designing for radials, not rings, but people have different views.

In terms of what circuits to have, the items on the list below may not all apply to you, but they are worth looking at to get you thinking:

1. Upstairs sockets
2. Downstairs sockets
3. Kitchen sockets
4. Circuit for appliances
5. Cooker circuit
6. Non-RCD circuit for F/F
7. Non-RCD circuit for CH boiler
8. Dedicated circuit for hifi
9. Dedicated circuit for IT equipment
10. Upstairs lights
11. Downstairs lights
12. Immersion heater
13. Shower
14. Alarm
15. Supply for outside lights
16. Supply for garden electrics
17. Supply for shed/garage

Plus any peculiarities brought about by your house layout & construction - e.g. in mine because of solid floors and where the rest of the sockets are, I have a radial just for one socket in the hall, the doorbell and the porch lights.

Plus a few spares on RCD & non-RCD sides for expansion beyond that for future unforeseen needs.

Still not decided on best way to do the outhouse, probably leaning towards running 6m SWA straight from the CU right into the outhouse and then just a few sockets off that and one light. the RCD in the house will protect the downstairs ring and the outhouse. it could also do the upstairs ring but as none of the sockets are likely to be used for equipment outside then there is no special need.

1) Do not have the outhouse supply cable on the RCD side of the house CU - put an RCD CU in the outhouse and run sockets & lights from that.
2) Do you have the issue of exporting a PME earth to the outhouse, and if so have you decided what to do? ( http://www.iee.org/Publish/WireRegs...matters_electrical_installations_outdoors.pdf )

I was originally going to do the outhouse in 6mm cable but 2 people have told me to just use 2.5 and they are electricians. i thought 4mm would probably be enough but 6 would be better. im thinking 32A maybe better and if needs be put in a 40A at a later date.

The mcb is selected for the sole purpose of protecting the cable. Select the cable by calculating your design current, then look in your OSG and select a suitable mcb to protect that cable.

See here for a handy summary of the principles.
. .
. .
. .
Edited to use a smaller font for the IEE link, as it was responsible for triggering horizontal scrolling - sorry.

 

[james 29]

Bas, thats a great link for the outhouse but one question,

If i understand it the author advocates taking a supply to the garage but no earth if you have installed a TT. No two earthing ststems simultaneously accessible.

Surely the only problem with this is due to the size of the cable being took to the garage. An earthing system which is pme is straight down to an earth electrode anyway.

Just curious if this was the main reason.

If you ran a 16mm 3 core from the cu tied to a seperate TT earth cant see any problems.

 

[ban-all-sheds]

The problem area is when the outbuilding contains extraneous-conductive-parts, e.g. a water supply, or structural steelwork etc.

They will be at local earth, but an exported earth from a distant PME supply will be, or could be, at a different potential, particularly if an earth fault occurs in the house.

So either you do not export the earth to the outbuilding, and make the outbuilding TT, or you do export it and you also run a main equipotential bonding conductor from the extraneous-conductive-parts back to the supply MET, thereby making it all one equipotential zone.

After some discussion on the IEE site over the question I raised, the consensus was that if the supply cable is 10mm² or greater, the cpc can do double duty as the bonding conductor.

 

[james 29]

ok cheers

 

[Spark123]

Please remove

 

[YCWB]

Hi, thanks everybody for the replies.

I know the work is notifiable and i know the correct way of going about it. I have 3 options.

I know a guy who will do as somebody suggested, he will come and inspect the work on 3 visits and do the testing at the end.

I can inform building controll and go through it that way, but building controll in my area dont like anybody at all doing this and they are insisting on paying BC and also paying an external contractor to come and test the work because they dont have electricians working for them. I know this isnt what they are suposed to do but that what they are insisting.

I have an EAL domestic installer qualification which allows me to register with NIC, ELECSA etc. Im not an electrician by trade and dont need to get work as one so im not going to go with the NIC. I do need to be able to do my own rewires in houses but i dont make a living from it. I am in the property game.

I have access to a Megger MF 1502 and i have the Minor works, Electrical Installation and Periodic Forms. I also have all the approved docs (Part P, A, B, E, etc), onsite guide......

Now thats out of the way, i would like to get all my design right then decide how im going to go about it. For now the outhouse isnt a major issue because it can be done at a later date but id like to decide how its going to be done.

The outhouse is very small, its about 1.5m by 1.5m and will only contain a washing machine, tumble dryer, electric heater and one light. An extra socket outlett will also be needed incase something like a drill needs to be plugged in. There isnt a water supply, no gas supply and not metal parts of the building.

The house has a TN-S supply.


This is the design i was going to use

1. 32A mcb - RCD Prtoected - Ring Circuit - 2.5 sqmm twin and earth - Downstairs sockets. Living room, kitchen, dining room, downstairs hall. Kitchen will have a dish washer, a combined fridge/freezer which is inbuilt in the kitchen units, electric oven and a hood, microwave, kettle, toaster.

2. 32A mcb - Not RCD Protected - Ring circuit - 2.5 sqmm twin and earth - Upstairs Sockets. 3 bedrooms and loft

3. 6A mcb - Not RCD Protected - Lighting - Downstairs. 1x ceiling rose in the living room, dining room, hall and kitchen.

4. 6A mcb - Not RCD Protected - Lighting - Upstairs. 1x celining rose in each bedroom.

5. Not RCD Protected - Electic shower - not decided on KW so will use 10 sqmm cable.

6. Outhouse - 32A mcb - Not RCD protected in house, but RCD in outhouse. 6 sqmm 3 core SWA. This will have a washing machine, tumble dryer, electric heater and one light. A trench will be dug, sand laid down, SWA ontop of the sand, sand ontop of the SWA and then concrete over the top.



After reading these posts i understand that it might be a better idea to have the fridge on a seperate radial that isnt rcd protected, and maybe a good idea to give the kitchen its own redail/ring circuit.

I understand why BAS likes radials, they are less dangerous as a ring is subject to a break in the ring. If a break occurs the ring will still work but 2.5 cable isnt designed to carry 32A.

 

[ban-all-sheds]

I know a guy who will do as somebody suggested, he will come and inspect the work on 3 visits and do the testing at the end.

Unless he is registered with a self-certification scheme, and lies on official documents about him having done the work, this is not an option in its own right - it's part of the option of DIY-ing with advance notification to LABC.

I can inform building controll and go through it that way

Legally you must, if you DIY or if the work is done by a non-registered electrician.

but building controll in my area dont like anybody at all doing this and they are insisting on paying BC

Yes - you have to pay them. This is not one of the things they are not supposed to do. When you submit a Building Notice you have to pay their fee - it's what the law says.

and also paying an external contractor to come and test the work because they dont have electricians working for them. I know this isnt what they are suposed to do but that what they are insisting.

You're absolutely right - they are not supposed to do that, and the belief of the ODPM is that it is unlawful for them to do that.

Is this rewire a stand-alone activity, or is it associated with other building work for which you really do need LABCs involvement? Are you in a position to push back at them really hard, and make it crystal clear that not only will you not pay for them to hire an electrician, or pay to hire one yourself, but also that if you have paid their fee, and they do not issue you with a completion certificate at the end you will take action against them for the refund of the fee?

I have an EAL domestic installer qualification which allows me to register with NIC, ELECSA etc. Im not an electrician by trade and dont need to get work as one so im not going to go with the NIC. I do need to be able to do my own rewires in houses but i dont make a living from it. I am in the property game.

I have access to a Megger MF 1502 and i have the Minor works, Electrical Installation and Periodic Forms. I also have all the approved docs (Part P, A, B, E, etc), onsite guide......

If you are genuinely qualified to the level that would allow you to register to self-certify, and the test equipment is in calibration, and you know how to use it, then why not register? You say that you want to do rewires in houses - i.e. you're going to encounter this notification issue again and again. Even if the LABC play ball and don't make you pay any more it doesn't take many notification fees to cover the cost of registering, and that's before you factor in the opportunity costs of dealing with the hassle, and the usefulness of being on friendly terms with LABC if you're into property development...

Alternatively, if you are genuinely qualified to the level that would allow you to register to self-certify, and the test equipment is in calibration, and you know how to use it, then why not just do the work, notify LABC, pay their fee, provide them with the EICs and then take action against them to force them to issue the completion certificate. If you have a solicitor who is a property law expert, it would be worth running it past him - to my reading the Building Regulations are quite clear on the responsibility of LABC to issue a certificate, but I'm not a lawyer.

The outhouse will contain a washing machine.

There isnt a water supply

An interesting combination.....

The house has a TN-S supply.

Fine - make sure your EFLI is OK on the outhouse circuit, as Ze can be high-ish with TN-S, and away you go.

5. Not RCD Protected - Electic shower - not decided on KW so will use 10 sqmm cable.

Really should be on the RCD

6. Outhouse - 32A mcb - Not RCD protected in house, but RCD in outhouse. 6 sqmm 3 core SWA. This will have a washing machine, tumble dryer, electric heater and one light. A trench will be dug, sand laid down, SWA ontop of the sand, sand ontop of the SWA and then concrete over the top.

I assume you've done the volt-drop etc calcs, and that the cable will be deep enough, bearing in mind that concrete might be removed with powered tools & machinery in the future. Warning tape would be a good idea. And even though it's a small shed, someone might build a bigger one - the materials cost of 10mm² SWA is not much more than 6mm²...

After reading these posts i understand that it might be a better idea to have the fridge on a seperate radial that isnt rcd protected, and maybe a good idea to give the kitchen its own redail/ring circuit.

Yup. If it were me I'd also seriously consider installing a cooker circuit just in case it's ever needed.
And I'd think about a separate circuit for the boiler, to make it easy to run it off a UPS or a standby generator.

I understand why BAS likes radials, they are less dangerous as a ring is subject to a break in the ring. If a break occurs the ring will still work but 2.5 cable isnt designed to carry 32A.

And problems with unbalanced loading, and problems with people spurring from it...

Let's put it this way - if they didn't already exist, do you think that the IEE would consider introducing them into the regs?

 

[Pensdown]

Unless he is registered with a self-certification scheme, and lies on official documents about him having done the work, this is not an option in its own right - it's part of the option of DIY-ing with advance notification to LABC.

This can be an option. For example, I don't do the installation, it's done by my company and it's up to me who I send to carry out the installation. I send a labour to do the donkey work (cheaper) and send a sparks out to do the terminating and testing. This is done on small and large projects. So long as the company or approved person takes the responsibility for the installation and if they have designed it and monitored the installation there is no problem. We and many others have been doing this for years with self builders and since PP this has not changed. If people want to go that route they have not got to notify as the PP contractor will sign it off as his job, in a sense he has just used un-paid sub contract labour. Of course, the persons ability has to be assessed before hand but normally most of them are more than capable of pulling the right cable to the right place via the right route

PS, if they are not capable, from now we are going to smack them round the back of the head with a rolled up copy of PP

 

[vince knight]

1. Upstairs sockets
2. Downstairs sockets
3. Kitchen sockets
4. Circuit for appliances
5. Cooker circuit
6. Non-RCD circuit for F/F
7. Non-RCD circuit for CH boiler
8. Dedicated circuit for hifi
9. Dedicated circuit for IT equipment
10. Upstairs lights
11. Downstairs lights
12. Immersion heater
13. Shower
14. Alarm
15. Supply for outside lights
16. Supply for garden electrics
17. Supply for shed/garage
    
    
    Outside lights should also be on the RCD side of the board.
    
    Vince

 

[Adam_151]

If you are genuinely qualified to the level that would allow you to register to self-certify, and the test equipment is in calibration, and you know how to use it, then why not register? You say that you want to do rewires in houses - i.e. you're going to encounter this notification issue again and again. Even if the LABC play ball and don't make you pay any more it doesn't take many notification fees to cover the cost of registering, and that's before you factor in the opportunity costs of dealing with the hassle

An interesting idea ban, and one that I intend to give serious thought to myself one day, as it would be nice to be able to do electrical work at home, and for friends and relatives etc without breaking the law, I'm not ready to take such a step yet, I'd need to get at least my 2381 first, but one day , one thing that looks certain is, I'd end up paying less to do electrical work legally, than I would be to drive a car legally ... (the joys of being a young male...)


Oh, and the extending PME equipotential zone thing, i've always wondered why you can't just install the separate MET for the outbuilding, do the bonding and have it as a separate equipotential zone, rather than have the cable size sufficent to extend the house equipotenial zone, a pipe running between them be bonded to both at the points of entry, as opposed to the other way where it runs within the equipotenial zone, I guess this is probably another one for the IEE forum now I've finished annoying them with adiabatic equation questions...