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Discussion Starter · #1 ·
Hi all

I'm new to the EV game and I'd settled on a pod-point for my home charger. We have a garage that's attached to the house, but is some distance from the main consumer unit and meter. The garage has a secondary consumer unit with room for the charger. I've sent my pictures to Pod Point and they say the following:

"We require for the garage fuse board to either by under a type A RCD protection or not RCD protected at all.

The current RCD protection on your garage fuse board is a type AC.

We will please need from you to change the RCD protection to a type A or to move one of the free MCB to a non RCD protected side of the garage fuse board. "


I've attached a picture of the secondary fuse board. A quick google confirms that the RCD is indeed AC. Can anyone advise what I need? Can i simply replace the RCD with a Wylex type A one into the existing board, or do I need a whole new unit? Is it a simple, DIY job or something best left to a professional?

Thanks in advance to anyone who can help.

Cheers
MR M
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Bit of a hodge podge of different MCBs in that board, too, some pretty old. Easy job to get the RCD changed to one of these: https://cpc.farnell.com/wylex/gb6-wrds100-2/2p-30ma-100a-dc-type-a-rcd/dp/PL16214 but frankly I would also have a look at tidying up that board at the same time, a couple of new, matching (from a type approval perspective) NHXB16 MCBs to replace those ancient NSB16s would only cost about a fiver for the pair.

The other question is what size is the sub-main feeding this board. This depends on the length, as well as the new total load, but as there's an immersion running off that board then that, plus an allowance for the sockets, boiler and lights, will have to be added to the current needed for the charge point. Unless the sub-main is at least 10mm² then there's a fair chance that it may not be hefty enough to run a charge point as well as the existing loads.
 

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Discussion Starter · #3 ·
Many thanks! The house is only 4 years old and the board hasnt been touched since we've been in it the last 3 years. It was a self build (not by us) in 2017. Strange that old components are being used!?

Attached is a pic of the main board. I spoke to the previous owner who confirms that the cabling to the garage is 6mm 3 core. Distance wise, it's maybe 25 metres, but that's a bit of a guess. The garage has a biomass boiler running in it. The immerser is a fail safe should the boiler ever go down. It'll rarely be used.

We were looking at a 7kw charger. Do you think this is possible given the current setup?

Again, thanks for your time and effort in assiting.

MR M
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I suspect you're going to be out of luck in being able to connect to the garage cable as it is at the moment. It looks as if the load at the garage is (using the diversity method in the OSG to BS7671:2018, Appendix A) :

Immersion heater = 13 A (100% of 3 kW)

Boiler = 6 A (100% of 6 A)

Sockets = 13 A (10 A + 50% of 6 A)

Lights = 4 A (66% of 6 A)

which gives a total of 36 A, hence the 40 A MCB protecting that cable. That leaves only 4 A of headroom, and the charge point needs 32 A.

It is acceptable to use judgement instead of the table in Appendix A, and I think it's probably reasonable to derate the boiler, sockets and lighting by a further 50% or so, but it isn't reasonable to derate the immersion at all. Even pushing things like this doesn't give enough headroom to run a charge point from that CU, though.

It looks as if you're going to have to see if you can either uprate the sub-main to the garage, find another location for the charge point, or use a load limiting charge point to charge the car at a lower rate if other equipment is on, I'm afraid.

As for the age of the installation, all I can say is that there are bits there that are well over ten years old. For example, fire resistant consumer units (i.e. metal cased ones) have been required in dwellings since the 3rd amendment of the 17th Edition of BS7671, in January 2016, so this installation has to be older than that.
 

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Discussion Starter · #5 ·
Many thanks for the very detailed response, even if it's not the news I was looking for.

I don't doubt what you say about the legality of the install, however, I know that the house foundations were not laid until 2017, so it all seems a bit odd !!

I'll have a re-think, thanks again.
 

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Many thanks for the very detailed response, even if it's not the news I was looking for.

I don't doubt what you say about the legality of the install, however, I know that the house foundations were not laid until 2017, so it all seems a bit odd !!

I'll have a re-think, thanks again.

Sorry to have raised other concerns, but, based on those photos, I'd have to say that the electrical installation in the house definitely wasn't compliant with the regs that existed in 2017, just because the main CU doesn't appear to be fire resistant. It looks to be an MK board from before 2015, as manufacturers started switching over to metal CUs before the 3rd amendment came into force in 2016. From the look of the CUs I'd say they were even older, as I think Wylex stopped making the NSB MCBs around ten years or so ago. I think if I were you I'd try and get hold of the EIC (Electrical Installation Certificate) for the installation. If you're in England or Wales then this will be lodged electronically with building control, under Part P. Be useful to check, as that certificate will have all you need to know about the installation, including the version of the regs it was approved to.

If you don't use the immersion heater, and don't use heavy loads on the socket circuit, then a load limiting charge point might be a good option. Realistically, the boiler probably only uses a couple of amps, and the lights probably the same, so if you don't have heavy loads on the sockets, and don't use the immersion, then you would probably still get a 32 A charge OK. If there are heavy loads on the other circuits, then the load limiting charge point will just slow down to keep things safe, at the expense of the time taken to charge the car.
 

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Many thanks! The house is only 4 years old and the board hasnt been touched since we've been in it the last 3 years. It was a self build (not by us) in 2017. Strange that old components are being used!?

Attached is a pic of the main board. I spoke to the previous owner who confirms that the cabling to the garage is 6mm 3 core. Distance wise, it's maybe 25 metres, but that's a bit of a guess. The garage has a biomass boiler running in it. The immerser is a fail safe should the boiler ever go down. It'll rarely be used.

We were looking at a 7kw charger. Do you think this is possible given the current setup?

Again, thanks for your time and effort in assiting.

MR M View attachment 146327
Many thanks for the very detailed response, even if it's not the news I was looking for.

I don't doubt what you say about the legality of the install, however, I know that the house foundations were not laid until 2017, so it all seems a bit odd !!

I'll have a re-think, thanks again.
Did you get an electrical cert when you purchased the house? Id question the competency of the installer if you have.. looks like they have had a rumage around their shed and thrown together whatever they had laying around..
 

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Did you get an electrical cert when you purchased the house? Id question the competency of the installer if you have.. looks like they have had a rumage around their shed and thrown together whatever they had laying around..

Mirrors my thoughts exactly. The general appearance, mismatched MCBs, pretty old CUs, the fairly slapdash way it's been put together, makes me suspect this may have been a DIY job. The question then is how it got building regs approval, especially if it's in England or Wales, as there's no way around proving compliance with Part P here. There should be a label on the CUs giving the date that the next EICR is due, and also the name and contact details for the electrician that signed the installation off (in this case, or who did the last EICR in older installations). If there is no label, then that's also a clue that this may have been a DIY job.

It's not unlawful to DIY an installation, but it does need to be done by a competent person, and be inspected and tested to show compliance with the requirements of BS7671 and also compliance with the Building Regulations (Part P and Part M).
 

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Discussion Starter · #9 ·
Thanks for the responses. We're in Scotland. It was a self build for the previous owner. He stayed in it for around 12-18m months before I bought it. I don't remember receiving any electrical certificates, however, it ws a little over 3 years now so I could be wrong.

I know the previous owner had an electrician do the wiring. I don't know much beyond that.
 

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Thanks for the responses. We're in Scotland. It was a self build for the previous owner. He stayed in it for around 12-18m months before I bought it. I don't remember receiving any electrical certificates, however, it ws a little over 3 years now so I could be wrong.

I know the previous owner had an electrician do the wiring. I don't know much beyond that.

Being in Scotland means that there's no formal building control approval, as Part P doesn't apply there (yet). You should instead have a copy of the EIC from the electrician, though. Might be an idea to request it, as it would be a useful thing to see, especially as it looks as if the installation may not comply with the regs.
 

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Discussion Starter · #11 ·
Thanks for all the advice. My garage unit is a metal unit, but the main consumer unit is indeed a MK plastic unit.

Awaiting the required RCD, but, based on your advice, I've did a little work.... work in progress!!
 

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Looks tidier, but I'm still concerned that this most probably wasn't an installation that was done by an electrician, and may not have been properly inspected and tested. Apart from the other clues, the standard labels are missing from that CU. It must have one stating that the installation is protected by an RCD and that the RCD must be tested at least every six months, for example, as that's a requirement in the regs. Section 514.12.2, on page 133 of the current regs, has this example wording, which hasn't changed for around 20 years or more:

146369


It's also a requirement to have a label giving the date of the last inspection (the EIC date in this case) and the date that the next inspection is due (usually ten years after the date on the EIC). The latter usually has the name and contact details of the electrician that did the work, although this isn't mandatory. The regs give this example label to show the information that must be on this label (from Section 514.12.1):

146370

These labels are often missing from older installations, before the date when RCDs became a requirement, but that's many years ago now, and any installation completed within the last 20 years or more should have labels like these. Their absence is a clue that whoever did the work was either a bit slapdash or (and I think this is most likely) wasn't actually done by a qualified electrician. If it were me, I'd spend half a day going around the installation physically checking everything and doing some basic testing, like measuring Ze (for a PME installation) or Ra (for a TT installation), testing the continuity of all CPCs, and ring conductors, testing the insulation resistance on all circuits, measuring Zs on every circuit, testing the functionality of the RCDs, and doing functional checks on outlets to test the correct polarity and operation of switches etc.


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Like you, I am in Scotland and have a house with a detached garage. I found it difficult to get a mainstream EVSE supplier to fit a unit in my garage as they generally wanted to run a whole new supply cable from my house, citing their lack of visibility of the existing cable. My garage is 30m from the house and has a separate consumer unit fed by an armoured cable underground. So I bought a Project EV (with no government grant) for £450, ran ethernet and CT cables to the garage myself in plastic conduit, fitted the EVSE to the wall myself and then got my regular local electrician to connect the mains cables with a new breaker in the distribution unit and to sign the certificate for me. With a garage 25m from your house, you may find the same problem as me getting a WiFi signal there so be sure to get a EVSE with an ethernet port. See this post about the Project EV and its load limiter features.
 

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Like you, I am in Scotland and have a house with a detached garage. I found it difficult to get a mainstream EVSE supplier to fit a unit in my garage as they generally wanted to run a whole new supply cable from my house, citing their lack of visibility of the existing cable. My garage is 30m from the house and has a separate consumer unit fed by an armoured cable underground. So I bought a Project EV (with no government grant) for £450, ran ethernet and CT cables to the garage myself in plastic conduit, fitted the EVSE to the wall myself and then got my regular local electrician to connect the mains cables with a new breaker in the distribution unit and to sign the certificate for me. With a garage 25m from your house, you may find the same problem as me getting a WiFi signal there so be sure to get a EVSE with an ethernet port. See this post about the Project EV and its load limiter features.
We done an install a few weeks ago, same issue with garage CU around 30mtrs away from the property/main CU.

Existing 6mm SWA installed to the garage CU, client didnt want to dig up their garden/pull up flooring for a new supply to be run. We used a Zappi with a Harvi, supplied from the garage CU in the end... The hardwired CT from the Zappi ran to the 6mm supply to the garage CU, this was limited to 35A. The Harvi was then clamped to the incoming meter tails of the property and transmits via RF, so theres no need to run extra data (if concerned that this is too far away, you can always extend the CT cable via CAT6 through the house/upstairs so that the harvi is closer to the Zappi). This was set to 80A, which is the incoming rating of the DNO fuse. We then placed the myenergi hub upstairs (close to the nearest extrenal wall to the zappi), connected to the clients router. No connection issues, and as ive said; if there were, we could just extend cabling inside the house on the hub or harvi.
 

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Thanks for all the advice. My garage unit is a metal unit, but the main consumer unit is indeed a MK plastic unit.

Awaiting the required RCD, but, based on your advice, I've did a little work.... work in progress!!
To add, I would just get a sparks in to carry out an EICR. Tell them in addition to the EICR, youd like them to quote for everything that needs to be rectified. Id do this before installing an EVCP, you will get a better idea of what needs doing ASAP and what can be improved upon. The EICR should only be a days wages and not too expensive...

Ive also noticed that you may have an issue with discrimination on your RCDs.. if the one on the main CU is 30mA...
 

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To add, I would just get a sparks in to carry out an EICR. Tell them in addition to the EICR, youd like them to quote for everything that needs to be rectified. Id do this before installing an EVCP, you will get a better idea of what needs doing ASAP and what can be improved upon. The EICR should only be a days wages and not too expensive...

Ive also noticed that you may have an issue with discrimination on your RCDs.. if the one on the main CU is 30mA...

I would agree 100% with this. Good spot on the discrimination, too, I'd not spotted that the main CU RCD feeding the garage wasn't a 100mA one. I get the strong feeling that this installation may well be a "DIY Dave" job. Easier to get away with a DIY installation in Scotland, too, with no Part P to contend with.
 
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