New EV Charging point

[alsdad]

Trying to cross the "t"s etc. before having the EV charger installed. As is always the case there are some spanners to get rid of.

The existing CU is remote from the meter, 7m tails with a 100A sub main switch at the meter end. TT earth with an unprotected 2.5mm cable coming out of the wall and disappearing under ground, no idea where the rod itself is. No label on the incomer fuse.

Charging point is to go outside the wall the meter is fixed to. The CU position would mean an extra charge for a long run.

Also want to have fitted a 16A socket for the motor home.

Rather that cable back to the CU the sparks recommended a second 7 way Wylex NM CU next to the meter. Henley block in the tails to the Sub Main Switch.

The DNO (UK Power Networks) inform me the tails to the meter are too small (16mm2) for the 100A fuse that would be needed. They had been booked to come and check the earth and uprate the fuse (if required) but CV19 means only essential work being done. Doesn't a dodgy earth count as a safety issue?

Sparks was to fit a Wylex NML CU but doesn't a TT earth mean a metal CU needs a RCD? That plus the isolator means a 7 way CU is only good for three circuits.

I know it won't work independently of the incoming supply but doesn't Solar PV constitute a second voltage source? No warning on the sub main that one exists.

I'm trying to coordinate EV charger, DNO attending and a Smart Meter install all together. I didn't hold up much hope but the Virus has made this even more unlikely

 

[muffking]

I'm not sure what you can achieve until the spark and DNO can do their bit other than get answers to a few of your questions.
Your tails are a bit long, but may be installed in such a way to mitigate this, although I would have liked to have seen 25mm tails on a 100A main fuse. It may be that the DNO simply drops you down to 80A depending on your maximum demand.

Is your 2.5mm cable definitely your main earth, or could it be bonding. Either way it's too small if it's 2.5mm and your spark will be able to sort this as the DNO will only maintain the earth if supplied by them.

The additional board will (I hope) have RCD protection as part of the 18th, although the main switch is not usually counted as part of your Ways, so you should have room for 5 MCB's or or 7 RCBO's. The EV charge point will also be rodded and the spark will sort the main earth for the additional board based on where it's being installed.

 

[AndyPRK]

The switch fuse should protect the long tails.

So just tails out the meter to worry about

 

[alsdad]

The new CU is a total of 7 (5+2). If we could get to the tails after the Sub main switch in theory the new CU wouldn't need the isolator as it and the Sub main switch are next to each other.

I don't know who installed it but the rod is definitely the earth for the incomer. The system was rewired 5 years ago and the sparks just joined his 4mm system earth to it. I think apart from the size that it should be in a conduit, not just coming out of the brick wall and down into the soil. When we bought the property I saw the cable and was confused as to what it was, traced it back and found it went back to the meter board!

The garage is on a 20m (4mm T&E) run to the other side of the house so we put another rod next to the garage. I trust that more if nothing else because the ground stays damp better down there but as the house earth it is still a small earth cable.

Cancellations have started so it all may be academic. The DNO want 25mm tails before they will install a 100A fuse.

 

[AndyPRK]

You may as well have new tails

METER > BIGGER TAILS > HENLEY JUNCTION BLOCK > HOUSE SWITCH FUSE (existing)
........................................................................... > CAR CHARGE CU

 

[muffking]

^^^ This ^^^

5 spare ways in your new board then, less the RCD. So that's EV, Commando and one other.

 

[winston1]

I’m trying to coordinate EV charger, DNO attending and a smart meter install all together. I didn't hold up much hope but the virus has made this even more unlikely

The smart meter crusade has been put on hold at this time. A good time for you to reconsider if you want one. There are lots of reasons not have one as has been discussed on these forums a number of times.

 

[ajohn]

Might be worth the OP watching this - long winded though. The install depends on the charger and cable to it may be swa plus mcb. Some with the earth voltage detection are also available now and would assume they also include the rcd.

He's done one on the ammendments as well. He doesn't like PEN's full stop.

 

[ericmark]

The problem is you must have enough distance between two types of earthing so you can't touch both together, this point was raised years ago with caravans, it is all well and good on a caravan site where fire regulations mean in the main 6 meters between caravan and any building, (3.5 meters at corners) so with that gap there is little chance you can touch a metal drain pipe, water pipe, gas or any other pipe connected to PME earth and the vehicle or charging point connected to the TT system.

However my old house has gas added after the house was built, as a result there was a gas pipe running length of the house connected to the house earth, so the drive could not be used to park a vehicle in which is being charged using a TT system.

The old 17th edition stated a TT system was required for a caravan site, but storing a caravan is not the same as using a caravan so where the caravan was close to the house often the house TN-C-S supply was used. And with early electric vehicle supplies I know often they did use a TN-C-S supply, across the road in my old house his van used for milk round was connected that way.

Seeing the Richard Hammond electric car crash where it took 5 days to put out the fire, it seems like caravans there should be a reasonable gap between any building and the car, but not seen any regulation stating that, the idea of parking a car in an integral garage while on charge is worrying to say the least, we have seen video and reports of phones going on fire while being charged on a bus, and that battery is very small compared with an electric car battery. So I would want any electric vehicle on charge to be like with caravans 6 meters away from a building, we know it makes sense, and at 6 meters no problem using TT earth for car charging and TN-C-S for the car.

However with earth faults we talk about a gradient, one of the reasons why we use an earth pit and a non conducting cover is so we can't touch the ground near to the earth electrode.

The regulations for cow sheds are far more stringent, cows have 4 legs much further apart than ours, and has a heart between its legs, so much easier to kill a four legged animal than two with a voltage gradient, we don't have a dog, or cat, but unless we erect some animal proof fencing we have to accept they may enter our premises, so in real terms have to protect them, be it a Welsh Black (cow) or Suffolk (sheep) we do have animals around both Wales and England.

As JW says we can use isolation transformers, and to be frank don't know why they are not used more, we had earthing problems with a narrow boat, we did not want shore earth connected to narrow boat hull, you can use diodes, but isolation transformer is best, and in the main the boat used batteries, so if the battery charger has a transformer then using a class II battery charger only connected to shore supply means no earth connected to boat, so with fork lifts and milk floats the battery charger resulted in every vehicle being isolated from the mains supply due to the transformer in the battery charger.

The cars often it seems have the battery charger built into the car, and this is where the problem lies.

So I have access to rear of my house, so installing a charging post 6 meters from house not a problem, however not sure about last 3 houses, all had off street parking, but non could you park a car using the off street parking even 3.5 meters from the house or garage.

But it's OK this government is getting practice at last minute U turns.

 

[SUNRAY]

so with fork lifts and milk floats the battery charger resulted in every vehicle being isolated from the mains supply due to the transformer in the battery charger.

I've worked on 2 forklift chargers and one of the tests on the sheet was to confirm the vehicle chassis, Charger enclosure and the adjacent trunking/unistrut were adequately bonded.

Some I've seen even use an additional earth lead before connecting charging plug.

 

[alsdad]

The smart meter crusade has been put on hold at this time. A good time for you to reconsider if you want one. There are lots of reasons not have one as has been discussed on these forums a number of times.

SMETS2 are transferable between suppliers which gets around a major reason not to have one. I know many of the objections but my main interest is integration with the PV system and the EV charger. At the moment the Solar panels can produce enough power to charge the car if I use the 3KW charger that came with the car at no cost all this week.

 

[winston1]

They may not fit a SMET2.

 

[ericmark]

I've worked on 2 forklift chargers and one of the tests on the sheet was to confirm the vehicle chassis, Charger enclosure and the adjacent trunking/unistrut were adequately bonded.

Some I've seen even use an additional earth lead before connecting charging plug.

This is the standard plug used on forklifts, wagon trailers and many other items needing a high amps DC under 70 volt, there is no option to fit an earth, just two connections, some times the chassis is connected to one terminal of the battery, but under 70 volt DC there has been no requirement for TT, or TN or any other earthing, the voltage is low enough not to need it.

The main point is milk floats, forklifts, electric bikes, mobility scooters, all have the charger remote from the vehicle, it is only the modern electric car where the charger is built into the vehicle rather than being building based, and fork lifts were normally charged in doors, there was a risk with hydrogen, and often there were extractor fans, and acid could leak so rubber gloves etc. However even when a lead acid battery explodes, it does not set anything else on fire, hydrogen burns rapid with a blue flame often with a squeak sound, but the hydrogen from lead acid batteries does not burn for 5 days like the batteries used in modern cars.

So with a mobility scooter, milk float, fork lift and the like charging in a garage is not a problem. And with electric cars charged at a safe distance from house, not really a problem, where the problem lies is when charged close to the house, so some one can touch car and house and a fire can spread to house, again on the open road at 70 MPH you can likely stop in time and get out with a fire, tunnels is another question, is it safe even to transport electric cars through a tunnel, never mind drive them?