Electrician query

[AVB]

I am having an electrical charging point installed for my new car. It is a 7kw charger. The circuit breaker in the house for the garage circuit is marked B16 (Is that 16 amp?) and the box in the garage has two breakers in it, one marked B6 and one B16.

 

Will the charger just be wired into the garage box or is there more work required? Upgrading breakers or putting different cable in between the house and garage? If so I'd like to have an idea. before the electrician comes in to install it?

 

Cheers

[John_R]

7kw is certainly more than 16 amps.

[vmaxphil]

32 amp supply minimum

[AVB]

32 amp supply minimum

So does that just mean that the circuit breaker will need changing? Or is there more involved than that?

[Rupert]

You need to ascertain the size of the supply cable coming to the garage, and is it on a breaker in the house?

[figgy]

Probably a new supply from the main board.

[ips]

7kw will require 32amp breaker and 6mm cable so depends what size cable is supplying the board in garage. If its big enough its just a case of changing the mcb

[AVB]

7kw will require 32amp breaker and 6mm cable so depends what size cable is supplying the board in garage. If its big enough its just a case of changing the mcb

Mmm that looks like it will be a problem. The cable to the garage just looks like normal 3 core. Putting a new one in will involve routing cable around the outside of the house (the board is at the back of the house, garage at front) then under paving to the garage.

 

I feared it would be bigger than just plug and play.

 

Thanks all.

[Loki]

Hi

 

Its always the supposedly smaller/simpler jobs that open up a far more 'involved' works schedule.......

Done right now will leave no room for issues aka problems later.

 

L

[JohnfromUK]

This raises an interesting point;

 

Where I live the house supply (i.e. into the house on the main fuse) is between 60A and 100A. Mine was recently upgraded from 60A to 80A, but the older installations are 60A.

 

A typical 'heavy' load with all these modern devices might be;

Car charger, 7 KW = 30A (worse still if the family has 2 cars as many will)

Electric shower, 10 KW = 43.5A

Oven/cooker rings, say 7.5 KW = 32A

Misc lights, towel rails, kettle, fridge, freezer, kitchen appliances etc. say 2KW = 8.7A

 

TOTAL load = 107A - more than enough to blow the main fuse - and probably just at Christmas when the cooking load is greatest! Life would be worse still with any electric heating, immersion heater, more cooker usage etc.

 

I have always been aware that I have to be a little careful not to exceed the main fuse rating (formerly 60A, now 80A) and know that even in my house with no car charger and no electric showers it is possible, though unlikely to blow the main fuse.

Edited September 22, 2017 by JohnfromUK

[AVB]

This raises an interesting point;

 

Where I live the house supply (i.e. into the house on the main fuse) is between 60A and 100A. Mine was recently upgraded from 60A to 80A, but the older installations are 60A.

 

A typical 'heavy' load with all these modern devices might be;

Car charger, 7 KW = 30A (worse still if the family has 2 cars as many will)

Electric shower, 10 KW = 43.5A

Oven/cooker rings, say 7.5 KW = 32A

Misc lights, towel rails, kettle, fridge, freezer, kitchen appliances etc. say 2KW = 8.7A

 

TOTAL load = 107A - more than enough to blow the main fuse - and probably just at Christmas when the cooking load is greatest! Life would be worse still with any electric heating, immersion heater, more cooker usage etc.

 

I have always been aware that I have to be a little careful not to exceed the main fuse rating (formerly 60A, now 80A) and know that even in my house with no car charger and no electric showers it is possible, though unlikely to blow the main fuse.

 

 

The average bod, and I include myself in that respect, would have no idea about that and would just wonder why the fuse has blown! The good thing about car chargers is that you can schedule them to charge during the night, taking advantage of off-peak power if you have such a thing, so unlikely to be in completion with other appliances. I have just looked at my main fuse (I didn't know I had one until you mentioned it) and it is marked 100A.

[JohnfromUK]

The average bod, and I include myself in that respect, would have no idea about that and would just wonder why the fuse has blown! The good thing about car chargers is that you can schedule them to charge during the night, taking advantage of off-peak power if you have such a thing, so unlikely to be in completion with other appliances. I have just looked at my main fuse (I didn't know I had one until you mentioned it) and it is marked 100A.

It is worth bearing in mind that some modern appliances, notably electric showers, 'instant' water heaters, car rapid chargers (for electric cars), and larger range style cookers with two more more ovens are all 'power hungry'. Too much 'on' at once can blow this fuse.

Older properties and properties in rural areas often have a fuse at less than 100A.

 

The other 'bad' thing is that this main fuse is sealed with a lead seal and must be changed by the supplier (or suitable qualified approved contractor).

Edited September 22, 2017 by JohnfromUK

[grrclark]

The points raised above by John are hugely pertinent in the EV debate. As it stands the UK does not have the grid capacity to deal with the proposed increase in EV's and neither is there sufficient upgrade capacity planning in place to support the increase.

 

The push towards smart vehicle chargers, especially for 32A charging points is so that the charging point can be throttled to suit the grid capacity and to avoid brown outs, however if all that does is step down the charging point to 16A or 10A then the time to charge will increase.

 

As it stands those that set their chargers to charge the EV overnight to take advantage of off peak costs may well find out their car is not charged in the morning as the grid could not sustain the required load.

 

I read a report fairly recently stating that if EV vehicle uptake reached a point of 3 EVs on average per street (30-50 houses) that we would have saturated current (no pun intended) grid capacity.

 

Edit to add: Further to that, there has been talk of using EV battery capacity as an on demand storage network to buffer peaks of demand across the grid, so effectively all the EVs become a big storage array. Not so handy if you want a fully charged car, but the grid has decided that your battery will be used to run Mrs Mugins' shower.

Edited September 22, 2017 by grrclark

[AVB]

What would the wise PW collective suggest? The current cable goes from the main board, somewhere through the house (probably through the ceiling void) down the house wall (possibly down the cavity?) then through the wall to the outside, under the patio and then up and through the detached garage wall into the garage board.

 

If I had known that the cable would need replacing I would have had it done when we had a lot of refurb work done earlier in the year. But I didn't. So I assume, the easiest, and aesthetically pleasing solution, would be to go outside at the back of the house from the MCB, around the house to the front, then under the patio to the garage. Would armoured 6mm cable suffice or something special needed for outside?

 

Thanks all.

The points raised above by John are hugely pertinent in the EV debate. As it stands the UK does not have the grid capacity to deal with the proposed increase in EV's and neither is there sufficient upgrade capacity planning in place to support the increase.

 

The push towards smart vehicle chargers, especially for 32A charging points is so that the charging point can be throttled to suit the grid capacity and to avoid brown outs, however if all that does is step down the charging point to 16A or 10A then the time to charge will increase.

 

As it stands those that set their chargers to charge the EV overnight to take advantage of off peak costs may well find out their car is not charged in the morning as the grid could not sustain the required load.

 

I read a report fairly recently stating that if EV vehicle uptake reached a point of 3 EVs on average per street (30-50 houses) that we would have saturated current (no pun intended) grid capacity.

 

Edit to add: Further to that, there has been talk of using EV battery capacity as an on demand storage network to buffer peaks of demand across the grid, so effectively all the EVs become a big storage array. Not so handy if you want a fully charged car, but the grid has decided that your battery will be used to run Mrs Mugins' shower.

 

There are c. 35 houses on my lane that has power provided by an above ground cable. I will be the third electric car on the lane. I can see all the lights dimming when I plug it in.

[JohnfromUK]

I think you need an electrician in to advise on the best cable routing and quote accordingly; 6mm is normally OK for 32A.

 

I also understand it is advisable (may even be a requirement?) to have a residual current device (rcd) that will operate on DC as well as AC (presumably due to the output from the charger to the batteries being DC) for vehicle charging points. Types A and B rcds I believe cover this, but some other types (that you may have in your existing consumer unit) do not.

I also understand that you are supposed to advise your electricity Distribution Network Operator that you have fitted an EV charging point ........

 

It is all quite a new field and a bit of a mystery to most of us.

[JohnfromUK]

The points raised above by John are hugely pertinent in the EV debate. As it stands the UK does not have the grid capacity to deal with the proposed increase in EV's and neither is there sufficient upgrade capacity planning in place to support the increase.

 

The push towards smart vehicle chargers, especially for 32A charging points is so that the charging point can be throttled to suit the grid capacity and to avoid brown outs, however if all that does is step down the charging point to 16A or 10A then the time to charge will increase.

 

As it stands those that set their chargers to charge the EV overnight to take advantage of off peak costs may well find out their car is not charged in the morning as the grid could not sustain the required load.

 

I read a report fairly recently stating that if EV vehicle uptake reached a point of 3 EVs on average per street (30-50 houses) that we would have saturated current (no pun intended) grid capacity.

 

Edit to add: Further to that, there has been talk of using EV battery capacity as an on demand storage network to buffer peaks of demand across the grid, so effectively all the EVs become a big storage array. Not so handy if you want a fully charged car, but the grid has decided that your battery will be used to run Mrs Mugins' shower.

It has quite escaped the politicians notice that we don't have the capacity for widespread electric vehicles;

• Many houses have 2 or even more vehicles
• The grid, local low voltage transformers and local distribution are in many cases near their maximum limits due to additional housing added onto legacy installations
• There are insufficient power stations (and these have a VERY long lead in time to get on line) to meet demand now, let alone in the future
• The overall distribute power/charge batteries/use power is actually currently a very inefficient process (mainly in that batteries are not currently very efficient) though improving all the time

Politicians have (as always) leapt in both feet first (just as they did with diesel tax breaks) without thinking this through .......... we have had some particularly disastrous energy secretaries at least one of whom was a crook as well ....... couldn't tell the truth about who was driving ........ got 8 months for perverting the course of justice.

[Brodie]

Apart from Telsa the depreciation on electric cars is horrendous.

Surely safest bet is to stick with proven technology - petrol - until the EV position is clearer.

Maybe someone will suddenly realise the benefits of hydrogen.

[JohnfromUK]

Apart from Telsa the depreciation on electric cars is horrendous.

Surely safest bet is to stick with proven technology - petrol - until the EV position is clearer.

Maybe someone will suddenly realise the benefits of hydrogen.

Do we know that hydrogen (on the surface I agree an ideal fuel, though storage vessels are very heavy as the pressure needed is huge) doesn't have similar NOx problems as diesel?

 

As I understand it, the high temperature in the cylinders created by burning diesel oxidises the nitrogen in the air causing the NOx pollution that seems to be the biggest problem (particular stuff can be filtered). NOx is less with petrol mainly because it burns cooler and with less excess air. My understanding was that hydrogen was also a 'hot burning' fuel?

 

Edit: Sorry straying off topic

Edited September 22, 2017 by JohnfromUK

[AVB]

Update. Electrician suggested a 60amp feed to garage to allow for the length of run and any additional services that we want to add in the future. He has also factored in longer cable to allow for us demolishing and moving the garage at a later date. So that is 50m of 16mm armoured cable and consumer unit plus tails! He has managed to run it low around the house and then down a wall to the garage. Doesn't look horrendous. Cost £755.