What does the term "Compounded RCDs mean?

[electronumpty]

The RCD in the EV charger in the photograph is type A.

Thought that has just occurred me is that even if you have a type A local to the charger and that will be covering the charger, you could have an issue with the type AC device which is covering the supply to the charger and other circuits... If the charger is pulling current with a distorted waveform and this has the ability to 'lock' an AC RCD by saturating the core (this effect was used in a particular made of loop tester). Then it would be possible if the charger was in use and this locking of the RCD was occurring, for the RCD at the origin to fail to trip on a fault occurring elsewhere in the installation.

So it's wrong then?

Please be aware I am totally stupid with regard to electrics, RCD and A's and B's. etc.

 

[flameport]

The installation does not comply with BS7671, as there are 2 RCDs on the same circuit, and the 40A device at the charger does not discriminate with the 32A MCB in the other consumer unit.
That does not necessarily mean it is unsafe.

How is the power to white plastic Hager consumer unit supplied? And what are the other two 'sockets' circuits actually for?

 

[electronumpty]

The installation does not comply with BS7671, as there are 2 RCDs on the same circuit, and the 40A device at the charger does not discriminate with the 32A MCB in the other consumer unit.
That does not necessarily mean it is unsafe.

How is the power to white plastic Hager consumer unit supplied? And what are the other two 'sockets' circuits actually for?

Good question.

I'll ask the company who installed it to explain themselves.
Cheers.

 

[securespark]

I looked at your other forum

Can't find it.

 

[Taylortwocities]

You have only shown us half of your consumer unit. The part that is RCD protected.
Show us the other half - the part with lighting etc. My guess is that part is not RCD Protected and the whole issue can be solved by moving the EV MCB to the other half of the consumer unit.

 

[DetlefSchmitz]

https://speakev.com/threads/how-much-olev-install-costs-you-must-be-joking.15405/

If this is out of order, can a moderator please delete...

BTW, a little surprised why a 40A RCBO is used for a 16A/32A max type device - I assumed (?) this was part of the installed unit, but no longer sure. tbh I know nothing about EV chargers ...

 

[Adam_151]

You have only shown us half of your consumer unit. The part that is RCD protected.
Show us the other half - the part with lighting etc. My guess is that part is not RCD Protected and the whole issue can be solved by moving the EV MCB to the other half of the consumer unit.

Provided of course, TTC, that the Cable is not concealed in a wall

 

[ericmark]

I do remember looking at EV chargers and the earthing system has been under debate. As with caravans and boats sites and marinas must use TT supplies and the public charge points are the same. But with a private charge point turning whole house to TT is rather extreme and so there was a book brought out by the IET detailing what could and could not be done. I have not bought that book but I am lead to understand a TN supply can in some cases be used.

What it would seem really matters is how the car is earthed or not earthed. I had same problem with a boat, the only safe way seemed to be using an isolating transformer, however the battery charger on the boat already had an isolation transformer built in. So for us simple method was to use a class II battery charger and not import the earth. 230 volt was from the inverter even when on shore supply.

The regulations do stipulate RCD fitted in both shore supply and the boat and caravan site and the caravan both are 30 mA within 40 mS so to say not permitted to have two RCD's of same size on same supply is daft as clearly the regulations require it.

As to testing that is another problem. It would clearly need an isolating transformer between the two RCD's to be able the test the second one. I see the argument that the type AC may trip first so stopping the test on the type A however unless you have a special RCD tester able to send DC pulses then all rather pointless.

With the Fluke only the 1652 and 1653 models can test with a 10 ~ 700 mA pulse DC and although the user can define the current used I personally don't have a clue on how you test a type A or B RCD. I would guess many electricians are the same. So what we really need to answer the question is some one with the IET book on installing electric car charging points. I have installed 100's of electric vehicle charging points but the battery voltage was under 75 volt DC. This is where the chance comes in. If over 75 volts DC then new set of rules.

 

[securespark]

You have only shown us half of your consumer unit. The part that is RCD protected.
Show us the other half - the part with lighting etc. My guess is that part is not RCD Protected and the whole issue can be solved by moving the EV MCB to the other half of the consumer unit.

I believe from the other forum that the board is a split load one with 100A iso on the other side.

The proprietor of one of the quoting firms called it a high integrity board but I can't see that.

 

[securespark]

I do remember looking at EV chargers and the earthing system has been under debate. As with caravans and boats sites and marinas must use TT supplies and the public charge points are the same. But with a private charge point turning whole house to TT is rather extreme and so there was a book brought out by the IET detailing what could and could not be done. I have not bought that book but I am lead to understand a TN supply can in some cases be used.

At one time my plan re EV chargers was not to export the earth and fit a rod for the (EV) installation, but that was when the DPC on EV chargers was just issued.

 

[kai]

Have you thought of supplying the car charger consumer unit via henley blocks instead, so that the two supplies are separated??
In the event of a fault in the car charger, it won't affect the rest of the house.

 

[electronumpty]

Have you thought of supplying the car charger consumer unit via henley blocks instead, so that the two supplies are separated??
In the event of a fault in the car charger, it won't affect the rest of the house.

Having now had the chance to look up Henley blocks (not knowing what they were) it does seem odd that the charger links back to the consumer unit at all. I think there would have been (maybe with a bit of shuffling) enough space to fit all of the bits inside the house Separate GSM meter specifically for the EV Charger) into the meter cupboard.

 

[Taylortwocities]

Usually the meter cupboard is reserved for Electricity Company equipment only.
The back board often has this printed on it.

 

[Adam_151]

SS, (or anyone who has had any dealings with EV chargers)..

As someone who hasn't got involved with EV chargers much, is anyone able to tell me what the GSM meter gets fitted for, I am guessing there is some kind of subsidy towards energy that is used to charge an EV?

 

[electronumpty]

SS, (or anyone who has had any dealings with EV chargers)..

As someone who hasn't got involved with EV chargers much, is anyone able to tell me what the GSM meter gets fitted for, I am guessing there is some kind of subsidy towards energy that is used to charge an EV?

Just a subsidy toward the charger only. I bought my electric car secondhand so did not receive anything from the government for buying it.