Hi All
Background: electronics engineer, done tons of DIY electrics wiring including SWA stuff to outbuildings etc, and 3 phase many years ago.
Q1: We have a single phase supply. The fuse used to be 80A. One day we got a letter from Seeboard offering to upgrade it for free. So we went for it. A man came and changed the fuse for a 100A one. Just like that. What size is the incoming cable? Is is about 20mm OD which might suggest 16mm2 rather than 25mm2. The distance is about 25m. The only heavy appliance in the house is a 10kW electric shower.
I realise a fuse is for wire protection only and a 100A fuse, probably a piece of 16swg copper, will blow well before a 16mm wire.
The reason I ask is because I am getting the house ready for 3 phase (for electric car charging, one day in the distant future) and then the meter will be relocated to a box on the outside of the house, and I will need to run a cable to the existing consumer unit. Fairly obviously 25mm2 will be OK but it is awfully hard to get this cable in place so smaller the better. That run would be about 3m. (Yes I know it would be better to use the existing incoming cable (which will be disconnected at the supply when the 3ph goes in) but it is buried deep under concrete).
But then when this is done, that 100A fuse will not be there anyway, because this is all "internal".
Q2: Do UK Power Networks ever make any allowance on their 45cm duct depth and type requirement? On the phone they say absolutely never under any circumstances whatever, but they are right jobsworths in their tone and would say that In the past this wasn't done and not far from me is a 33kV cable about 1ft deep in soft soil House supplies were often a few inches deep (in concrete) or 1ft deep (in soil). They told me they don't use SWA because it doesn't last as long.
I ask because we had a drive done in block paving. Under it is about 12" of concrete and at the bottom of that concrete is a 8cm duct (standard gutter pipe) which I got laid, all the way from the road, to our garage, in preparation for the 3ph supply. I didn't get around to checking the power company requirements for the house supply until the concrete was done... So it isn't 45cm deep but I don't see how the cable could be damaged, with a foot of concrete on top of it, and it being in an 8cm pipe.
We do have a Plan B which is to run the prescription duct through a garden, but it would be nice to use the one under the drive.
I would be looking for 3 x 80A or so.
Q3: Does the power company ever care about what is connected after the meter? They never used to. In a previous house I installed a big box with a load of 3 phase stuff (switch, RCDs, etc) and they were happy. It is possible they thought an electrician did it. Well, I tried to find one but as soon as I mentioned 3 phase and the countryside location, they all wanted £500 per half day, so I did it myself. I used a big steel cabinet.
I hear stories nowadays of electricians refusing to do any work in a house, beyond changing a bulb, unless the consumer unit etc is ripped out and replaced to comply with latest wiring regs, and wonder if the power company is similar.
Obviously, after the meter will have to be a switch and RCD (or RCBO under the new regs?) before wiring continues to the rest of the house. I can get an electrician to install a cabinet with this in, with space for the meter, but presumably he won't touch the job if there is anything else in the house he doesn't like. So maybe I should install this cabinet (like I did on the other house many years ago) and do it so it looks like it was done by an electrician.
Thank you for any feedback
Background: electronics engineer, done tons of DIY electrics wiring including SWA stuff to outbuildings etc, and 3 phase many years ago.
Q1: We have a single phase supply. The fuse used to be 80A. One day we got a letter from Seeboard offering to upgrade it for free. So we went for it. A man came and changed the fuse for a 100A one. Just like that. What size is the incoming cable? Is is about 20mm OD which might suggest 16mm2 rather than 25mm2. The distance is about 25m. The only heavy appliance in the house is a 10kW electric shower.
I realise a fuse is for wire protection only and a 100A fuse, probably a piece of 16swg copper, will blow well before a 16mm wire.
The reason I ask is because I am getting the house ready for 3 phase (for electric car charging, one day in the distant future) and then the meter will be relocated to a box on the outside of the house, and I will need to run a cable to the existing consumer unit. Fairly obviously 25mm2 will be OK but it is awfully hard to get this cable in place so smaller the better. That run would be about 3m. (Yes I know it would be better to use the existing incoming cable (which will be disconnected at the supply when the 3ph goes in) but it is buried deep under concrete).
But then when this is done, that 100A fuse will not be there anyway, because this is all "internal".
Q2: Do UK Power Networks ever make any allowance on their 45cm duct depth and type requirement? On the phone they say absolutely never under any circumstances whatever, but they are right jobsworths in their tone and would say that In the past this wasn't done and not far from me is a 33kV cable about 1ft deep in soft soil House supplies were often a few inches deep (in concrete) or 1ft deep (in soil). They told me they don't use SWA because it doesn't last as long.
I ask because we had a drive done in block paving. Under it is about 12" of concrete and at the bottom of that concrete is a 8cm duct (standard gutter pipe) which I got laid, all the way from the road, to our garage, in preparation for the 3ph supply. I didn't get around to checking the power company requirements for the house supply until the concrete was done... So it isn't 45cm deep but I don't see how the cable could be damaged, with a foot of concrete on top of it, and it being in an 8cm pipe.
We do have a Plan B which is to run the prescription duct through a garden, but it would be nice to use the one under the drive.
I would be looking for 3 x 80A or so.
Q3: Does the power company ever care about what is connected after the meter? They never used to. In a previous house I installed a big box with a load of 3 phase stuff (switch, RCDs, etc) and they were happy. It is possible they thought an electrician did it. Well, I tried to find one but as soon as I mentioned 3 phase and the countryside location, they all wanted £500 per half day, so I did it myself. I used a big steel cabinet.
I hear stories nowadays of electricians refusing to do any work in a house, beyond changing a bulb, unless the consumer unit etc is ripped out and replaced to comply with latest wiring regs, and wonder if the power company is similar.
Obviously, after the meter will have to be a switch and RCD (or RCBO under the new regs?) before wiring continues to the rest of the house. I can get an electrician to install a cabinet with this in, with space for the meter, but presumably he won't touch the job if there is anything else in the house he doesn't like. So maybe I should install this cabinet (like I did on the other house many years ago) and do it so it looks like it was done by an electrician.
Thank you for any feedback