Barriers to EV uptake - network reinforcement

As far as I can tell based on SSE round here, the DNO is busy enough maintaining what it has on a 'fire brigade' basis (sometimes quite literally fire brigade actually), with not much slack for anything that looks like planning ahead for supplying all  3 phases to each house and fatter street cables generally.  The infrastructure is dated, most of it more than half a century old, and some sections are pre-war, and is certainly already creaking a bit at the current level of 5 to 10 amps per house average.

It is worth looking at a typical DNOs ADMD figures for new housing, which are around the 2kw per house mark, and realize these numbers, used to size substations, street cabling and the 11 and 33kV distribution behind it, are  quite a bit more generous than previous versions used to size the network we currently have in many places.  If too many houses suddenly become a 30A load, or for that matter a  generator in sunny weather, the whole thing is way out of balance relative to the original cable sizing assumptions.

Most of the DNOs publish their LV network design rules and loading assumptions on the web, some require an email sign up, but they may be worth a quick read to calibrate expectations - 70 houses each phase with a 100A cut out may well share a couple of  400A fuses per phase at a 500kVA substation for example.

The BEAMA report is interesting but light on detail, and I do not believe for a moment that earth mats at substations will be the dominant future cost (figure 7) - if that was it we could start driving steel scaff poles instead. I think street cables and house supplies will dominate, and I am surprised they are not mentioned. Maybe the last leg of the LV network is not sexy enough for BEAMA to consider. (but without it the lights go out ! )

Mike.

As far as I can tell based on SSE round here, the DNO is busy enough maintaining what it has on a 'fire brigade' basis (sometimes quite literally fire brigade actually), with not much slack for anything that looks like planning ahead for supplying all  3 phases to each house and fatter street cables generally.  The infrastructure is dated, most of it more than half a century old, and some sections are pre-war, and is certainly already creaking a bit at the current level of 5 to 10 amps per house average.

It is worth looking at a typical DNOs ADMD figures for new housing, which are around the 2kw per house mark, and realize these numbers, used to size substations, street cabling and the 11 and 33kV distribution behind it, are  quite a bit more generous than previous versions used to size the network we currently have in many places.  If too many houses suddenly become a 30A load, or for that matter a  generator in sunny weather, the whole thing is way out of balance relative to the original cable sizing assumptions.

Most of the DNOs publish their LV network design rules and loading assumptions on the web, some require an email sign up, but they may be worth a quick read to calibrate expectations - 70 houses each phase with a 100A cut out may well share a couple of  400A fuses per phase at a 500kVA substation for example.

The BEAMA report is interesting but light on detail, and I do not believe for a moment that earth mats at substations will be the dominant future cost (figure 7) - if that was it we could start driving steel scaff poles instead. I think street cables and house supplies will dominate, and I am surprised they are not mentioned. Maybe the last leg of the LV network is not sexy enough for BEAMA to consider. (but without it the lights go out ! )

Mike.