Downstairs Rewire.
Hi all, great forum have often lurked here. Just hoping to pick some brains. Before I start just like to say I've been in the trade (old school c&g) for 26yrs, worked on a mix of private work and large new builds. I'm not a sparky, but have done all of my home wiring over the years (my own not for others) - please don't harp on about notifible and I'll not bleat on about dire tradesmen. Basically its the home I'll be staying in until I snuff it and I want it to be the best it can be.
My CU is 10way Hager split board (3yr old)
RCD 63
Switch 100
PME Connected
House Load Upstairs (complete)
1x 2.5 Ring main (new)
1x 1.5 Lighting Circuit (new)
House Load Downstairs (getting gutted)
1x 2.5 Ring Main Living Room (old)
1x 2.5 Radial Kitchen (dire setup and old)
1x 10mm Shower (old)
1x 10mm Oven (old)
1x 1.5 Lighting Circuit (old)
The new is up to code (2yrs old), the old is Red n Black, cable is all fine, set up is poor and a radial in 2.5 in kitchen ffs. House is 1950's looks like its had 3 rewires over its life span, some form of braid to lead and tin to TE Red n Black. I've had the property for 4yrs and have renovated the upstairs (full gut) installed new ring main and lighting circuit and new CU.
Earthing, all pipe work in the house is copper and everything has been cross bonded there are two external earth rods in vertical 100mm pipe work fill with chippings (nicely done and hidden) one is connected to the CU and the other to a 22mm hot water copper (25mm earth). The PME was available on the main board but the local sparky who installed the consumer unit (I was away building a morrison at the time) did not connect the earth to the PME from the new CU (its never been connected) he also done a bunk without leaving me a cert and worse than that did not connect the earth for the shower in the CU as it would not reach due to his placement of the CU, plus two others were not connect lighting and power. Anyhoots that's another story just narked me as my kids were using it for 2 whole weeks before I came home, so I removed the CU and installed it all as it should be. Had another sparky call around in the week and he connected the PME and checked the board. Both earth rods were left connected.
First question, technically the earth rods can be disconnected as the PME is connected. However my view is leave them in. When we install HV and LV units on site we often create a large earth mat (300m sq). So I'm thinking what's the harm, I look at it like this, if I'm in the bath and the misses throws a live toaster in for looking at her hot sister - I'm probably dead - but if I was swimming in the sea then throw away woman. Whilst 17th edition would say you don't need those earth rods, surely its better to have them to assist in spreading out any current from a failure? Or is my thinking totally flawed on this? My view is bond everything and disperse over a wide area. What harm can it do?
2. Cable size - Lighting. I am lucky enough to have some cable from site from our generous lads (100m x 1.5mm). The cable itself is much thicker, I take it this is due the long runs needed on large stores. I don't mean the copper, but the insulation. ie 1.5 TE is 1.5 but the plastic is thicker than the normal household grey TE we get from wholesalers. My plan was to run this as my main lighting circuit, and then if needed use 1.5mm normal from junction boxes or even 1.0mm for fittings that are restrictive ie rows of GU10 with Leds or kitchen unit lighting etc (B6 mcb,). Clearly for a house that is probably overkill but are there any pitfalls to installing this way or should I just use standard 1.5 TE. All cable will be in metal cover strips for wall, render & plaster and oval cable ducting for ceiling and cable tray. (lighting circuit only) Only 1 juction box per run of lights then loop in as per normal.
3. 2.5 TE pretty straight forward. Ring for kitchen and ring for living room using MK sockets. FCU for basic appliances and extractor - easy.
4. Oven/hob - currently 10mm powers a single oven/hob appliance. I'll keep this short as I know many questions have been asked on this issue. I'll be having separate oven and hob at different locations. I can see you can buy splitter boxes online. My gut is I don't like that idea because of the mis-match in current between hob and oven in relation to the mcb on that circuit. To me I would prefer to install a separate radial for both and put them on the non rcd side of the CU and install a RCBO for each based on their demands - probably 16 oven 32 hob will have to work them out. Again I have 50m of 10mm cable. Whilst I know ovens can be run on 2.5 ring, I think that's nuts as you've not got any headroom should you change equipment, not to mention how powerful some kitchen counter goods are becoming - I'll give that a big miss. So I'm thinking 10mm to 45 switch (hob) and 6mm flex to appliance. Oven 6mm to 20 db amp FCU switch and 6mm flex to oven. Should the oven get changed to double oven then again there is headroom. Any views? Could I use 10mm for Oven to 20 fuse/amp switch and then drop to 6mm (I have 50m of 10mm but no 6mm) then use the correct size RCBO for the oven.
5. Shower is 8kw - cable is 10mm continuous run from CU to 45amp pull cord outside the bathroom. Not renewing this but will support the cable as its unsupported at the moment.
I have a copy of the 17th ed and loads of BS in pdf. I'll be no doubt reading up on them, but there is nothing like chatting to people that know their stuff as I said I'm not after the minimum, basically if its your house what would you do. I have 100m 1.5, 50m 2.5 and 50m of 10mm, 20 MK 2 gang socket (given to me, so costs are already down)
Thanks all, any advice, help or food for thought always appreciated. Only in design phase at the moment. When I speak to local sparks I get a mixed bag of replies mostly - nah don't bother with that tack the cable to the wall n render, tack them to the joists, and just go 6mm and I'd not bother with the RCBO for Hob n Oven, disconnect the earth rods you don't need them and you don't have to cross bond now, how much do you want for the 10mm etc
Cheers Bill
Hi all, great forum have often lurked here. Just hoping to pick some brains. Before I start just like to say I've been in the trade (old school c&g) for 26yrs, worked on a mix of private work and large new builds. I'm not a sparky, but have done all of my home wiring over the years (my own not for others) - please don't harp on about notifible and I'll not bleat on about dire tradesmen. Basically its the home I'll be staying in until I snuff it and I want it to be the best it can be.
My CU is 10way Hager split board (3yr old)
RCD 63
Switch 100
PME Connected
House Load Upstairs (complete)
1x 2.5 Ring main (new)
1x 1.5 Lighting Circuit (new)
House Load Downstairs (getting gutted)
1x 2.5 Ring Main Living Room (old)
1x 2.5 Radial Kitchen (dire setup and old)
1x 10mm Shower (old)
1x 10mm Oven (old)
1x 1.5 Lighting Circuit (old)
The new is up to code (2yrs old), the old is Red n Black, cable is all fine, set up is poor and a radial in 2.5 in kitchen ffs. House is 1950's looks like its had 3 rewires over its life span, some form of braid to lead and tin to TE Red n Black. I've had the property for 4yrs and have renovated the upstairs (full gut) installed new ring main and lighting circuit and new CU.
Earthing, all pipe work in the house is copper and everything has been cross bonded there are two external earth rods in vertical 100mm pipe work fill with chippings (nicely done and hidden) one is connected to the CU and the other to a 22mm hot water copper (25mm earth). The PME was available on the main board but the local sparky who installed the consumer unit (I was away building a morrison at the time) did not connect the earth to the PME from the new CU (its never been connected) he also done a bunk without leaving me a cert and worse than that did not connect the earth for the shower in the CU as it would not reach due to his placement of the CU, plus two others were not connect lighting and power. Anyhoots that's another story just narked me as my kids were using it for 2 whole weeks before I came home, so I removed the CU and installed it all as it should be. Had another sparky call around in the week and he connected the PME and checked the board. Both earth rods were left connected.
First question, technically the earth rods can be disconnected as the PME is connected. However my view is leave them in. When we install HV and LV units on site we often create a large earth mat (300m sq). So I'm thinking what's the harm, I look at it like this, if I'm in the bath and the misses throws a live toaster in for looking at her hot sister - I'm probably dead - but if I was swimming in the sea then throw away woman. Whilst 17th edition would say you don't need those earth rods, surely its better to have them to assist in spreading out any current from a failure? Or is my thinking totally flawed on this? My view is bond everything and disperse over a wide area. What harm can it do?
2. Cable size - Lighting. I am lucky enough to have some cable from site from our generous lads (100m x 1.5mm). The cable itself is much thicker, I take it this is due the long runs needed on large stores. I don't mean the copper, but the insulation. ie 1.5 TE is 1.5 but the plastic is thicker than the normal household grey TE we get from wholesalers. My plan was to run this as my main lighting circuit, and then if needed use 1.5mm normal from junction boxes or even 1.0mm for fittings that are restrictive ie rows of GU10 with Leds or kitchen unit lighting etc (B6 mcb,). Clearly for a house that is probably overkill but are there any pitfalls to installing this way or should I just use standard 1.5 TE. All cable will be in metal cover strips for wall, render & plaster and oval cable ducting for ceiling and cable tray. (lighting circuit only) Only 1 juction box per run of lights then loop in as per normal.
3. 2.5 TE pretty straight forward. Ring for kitchen and ring for living room using MK sockets. FCU for basic appliances and extractor - easy.
4. Oven/hob - currently 10mm powers a single oven/hob appliance. I'll keep this short as I know many questions have been asked on this issue. I'll be having separate oven and hob at different locations. I can see you can buy splitter boxes online. My gut is I don't like that idea because of the mis-match in current between hob and oven in relation to the mcb on that circuit. To me I would prefer to install a separate radial for both and put them on the non rcd side of the CU and install a RCBO for each based on their demands - probably 16 oven 32 hob will have to work them out. Again I have 50m of 10mm cable. Whilst I know ovens can be run on 2.5 ring, I think that's nuts as you've not got any headroom should you change equipment, not to mention how powerful some kitchen counter goods are becoming - I'll give that a big miss. So I'm thinking 10mm to 45 switch (hob) and 6mm flex to appliance. Oven 6mm to 20 db amp FCU switch and 6mm flex to oven. Should the oven get changed to double oven then again there is headroom. Any views? Could I use 10mm for Oven to 20 fuse/amp switch and then drop to 6mm (I have 50m of 10mm but no 6mm) then use the correct size RCBO for the oven.
5. Shower is 8kw - cable is 10mm continuous run from CU to 45amp pull cord outside the bathroom. Not renewing this but will support the cable as its unsupported at the moment.
I have a copy of the 17th ed and loads of BS in pdf. I'll be no doubt reading up on them, but there is nothing like chatting to people that know their stuff as I said I'm not after the minimum, basically if its your house what would you do. I have 100m 1.5, 50m 2.5 and 50m of 10mm, 20 MK 2 gang socket (given to me, so costs are already down)
Thanks all, any advice, help or food for thought always appreciated. Only in design phase at the moment. When I speak to local sparks I get a mixed bag of replies mostly - nah don't bother with that tack the cable to the wall n render, tack them to the joists, and just go 6mm and I'd not bother with the RCBO for Hob n Oven, disconnect the earth rods you don't need them and you don't have to cross bond now, how much do you want for the 10mm etc
Cheers Bill
