Rural home-charging setup

[LongRanger]

There’s been a number of threads recently about charging options, fused installs, garage limits, types of installation etc recently so thought I’d share a little install project that has been going on.

Thought it may provide some ideas for folks if they are trying to get a bit creative ....

We live in a very rural location, and there’s literally about 3 properties served by our power supply on the local spur from the substation.

Our house is a bit of a basket case in terms of bits added on, originally it was a “Crog Loft” style dwelling in about 1760 then a full height second storey and other sections were added later as living styles changed - so with that has come a bit of a bonkers set of electricity circuits - meaning I could only get a 16A circuit added for charging right next to the house. That was the simple bit.

To enable 32A charging, fortunately around a year ago (before a Tesla was even an option for me) we had an additional supply added to our outbuildings - as the transformer is literally behind the building. You can see the new supply going into the top corner of the concrete wall.

In the last month we had a trench 30m approx dug from front of outbuilding out to an area suitable to locate a supply point for power/charging. Cable run is around 50 metres, 10mm2

Then I’ve made a base/frame to provide a stable location for a “log store” that I’ve converted into a charging location, with some additional treated timber outside for weatherproofing / inside for stable mounting of the components.

The electrician has then come in and installed an additional consumer unit, 32A interlocked switch and 16A second unit and tested everything today. Reads 250V at the sockets with tests all passed for tripping/fault detection back to the main consumer unit in the barn.

I still need to finish off the base edges with 8” gravel board and fill with stone to aid drainage etc. Already under the Terram membrane is a layer of sand again to help with drainage.

Next step is to install the Juice Booster charger bracket and finalise cable hanging setup. More pics to follow.

 

[pgkevet]

That all looks good but I'm curious why you have the pent roof of the shed sloping to the door..tighter access and getting hit by the run-off?

 

[LongRanger]

It doesn’t really matter - rain here comes from all angles. It’s 1.5m high so not very tight access, in fact perfect arm-height to reach in and twist the interlock switch

Prevailing weather generally comes from the rear of the shed or the tree side, and drainage will be better out into the gravel drive as it all has the terram underneath. When charging in wet conditions the charger itself will be inside the shed with just the cable coming through the slot above the door.

 

[Neilman]

Might need a nice ornate sign on the door reading "Not a Loo"

 

[M3noob]

There’s been a number of threads recently about charging options, fused installs, garage limits, types of installation etc recently so thought I’d share a little install project that has been going on.

Thought it may provide some ideas for folks if they are trying to get a bit creative ....

We live in a very rural location, and there’s literally about 3 properties served by our power supply on the local spur from the substation.

Our house is a bit of a basket case in terms of bits added on, originally it was a “Crog Loft” style dwelling in about 1760 then a full height second storey and other sections were added later as living styles changed - so with that has come a bit of a bonkers set of electricity circuits - meaning I could only get a 16A circuit added for charging right next to the house. That was the simple bit.

To enable 32A charging, fortunately around a year ago (before a Tesla was even an option for me) we had an additional supply added to our outbuildings - as the transformer is literally behind the building. You can see the new supply going into the top corner of the concrete wall.

View attachment 581025

In the last month we had a trench 30m approx dug from front of outbuilding out to an area suitable to locate a supply point for power/charging. Cable run is around 50 metres, 10mm2

View attachment 581024

View attachment 581026

View attachment 581027

Then I’ve made a base/frame to provide a stable location for a “log store” that I’ve converted into a charging location, with some additional treated timber outside for weatherproofing / inside for stable mounting of the components.

View attachment 581028

View attachment 581029

View attachment 581030

The electrician has then come in and installed an additional consumer unit, 32A interlocked switch and 16A second unit and tested everything today. Reads 250V at the sockets with tests all passed for tripping/fault detection back to the main consumer unit in the barn.

View attachment 581031

View attachment 581032

I still need to finish off the base edges with 8” gravel board and fill with stone to aid drainage etc. Already under the Terram membrane is a layer of sand again to help with drainage.

Next step is to install the Juice Booster charger bracket and finalise cable hanging setup. More pics to follow.

Or wait until the sun shines to charge your car

 

[Artiste]

Nice job, and I always like to see people charging using a 32A commando as that’s what I do myself.

 

[pdk42]

Nice job, and I always like to see people charging using a 32A commando as that’s what I do myself.

Given the agro I've had with chargers I've often thought this might have been a better option - but as I understand it, it doesn't formally meet regulations for EV charging does it?

 

[Artiste]

Given the agro I've had with chargers I've often thought this might have been a better option - but as I understand it, it doesn't formally meet regulations for EV charging does it?

Unfortunately not. It was, of course, considered perfectly safe until regulations were updated, and I certainly don’t consider it to be a risk.

 

[Glan gluaisne]

Given the agro I've had with chargers I've often thought this might have been a better option - but as I understand it, it doesn't formally meet regulations for EV charging does it?

Unfortunately not. It was, of course, considered perfectly safe until regulations were updated, and I certainly don’t consider it to be a risk.

Just for the record, there has always been a requirement for additional protection in the event of a PEN fault for a charge point, just as there has always been a requirement for additional protection for the same reason for caravan outlets etc.

Until BS7671:2018 was published, this additional requirement was in a separate document, it only made its way into the wiring regs because the fitting of charge points has grown in popularity, so it made sense to incorporate the exact wording of what had been in a separate document into the regs themselves. The only changes that I'm aware of have been the recent (earlier this year) relaxation of the methods for meeting the requirement that's now in Section 722 of the regs.

As far as the law goes, then in England and Wales Part P of the building regulations applies to any outdoor circuit/installation, and in order to comply with Part P, and lodge the mandatory installation certificate on the building control accessible database, the safety requirements in the regs need to be complied with.

In general, exporting the PE any distance, or to an installation where there is a touch voltage risk in the event of af PEN fault, has always required that the installation be wired with its own earth electrode and RCD, as a TT installation. For example, when we were building our house I installed a temporary building supply with a commando outlet. I was required to wire that as a TT installation, and the DNO stuck a note reminding me of this requirement when they connected the supply.

Cheap and easy to do in the case of any installation where there is little risk of DC blinding the RCD, like a standard caravan commando power outlet. EVs made things more complex, and introduced the change to needing a Type B RCD around 10 years or so ago, when what is now in BS7671:2018 was first published.

 

[LongRanger]

.... RCDs are type B and the whole outbuilding install is TT'd. We had to do this initially as we have livestock and parts of the building have steel supports baked into the concrete

 

[Glan gluaisne]

.... RCDs are type B and the whole outbuilding install is TT'd. We had to do this initially as we have livestock and parts of the building have steel supports baked into the concrete

Perhaps worth making that clear, as the regs for a TT installation are not the same as those for TN, as the concern is primarily what happens if there's a PEN fault, something that obviously canny occur with a TT installation as there is no PEN. This was something that I guess your electrician took into account when completing and lodging the Part P installation certificate. The more onerous requirements in Section 722 specifically apply to a TN installation, which is now the most common type of installation in the UK as a whole.

Out of interest, where did you manage to source a 2 module Type B RCD? I've only been able to find wider ones, that are a PITA to fit into a small enclosure and leave room for anything else.

 

[LongRanger]

no idea - electrician dealt with all of that - I bought the enclosures and interlocked connectors and ordered the cable, plus built the wooden bits, at that point I handed over to the qualified person.

tbh I was just excited to see 250V like it was some sort of magical force appearing out of the ground - I'll get the safety certificate copy today or tomorrow so if there's anything interesting I'll share.

 

[Glan gluaisne]

I'd be interested if you could get the make and number from the Type B RCD, as it would be very handy to find a source for smaller ones, please.

 

[Artiste]

Just for the record, there has always been a requirement for additional protection in the event of a PEN fault for a charge point, just as there has always been a requirement for additional protection for the same reason for caravan outlets etc.

Until BS7671:2018 was published, this additional requirement was in a separate document, it only made its way into the wiring regs because the fitting of charge points has grown in popularity, so it made sense to incorporate the exact wording of what had been in a separate document into the regs themselves. The only changes that I'm aware of have been the recent (earlier this year) relaxation of the methods for meeting the requirement that's now in Section 722 of the regs.

As far as the law goes, then in England and Wales Part P of the building regulations applies to any outdoor circuit/installation, and in order to comply with Part P, and lodge the mandatory installation certificate on the building control accessible database, the safety requirements in the regs need to be complied with.

In general, exporting the PE any distance, or to an installation where there is a touch voltage risk in the event of af PEN fault, has always required that the installation be wired with its own earth electrode and RCD, as a TT installation. For example, when we were building our house I installed a temporary building supply with a commando outlet. I was required to wire that as a TT installation, and the DNO stuck a note reminding me of this requirement when they connected the supply.

Cheap and easy to do in the case of any installation where there is little risk of DC blinding the RCD, like a standard caravan commando power outlet. EVs made things more complex, and introduced the change to needing a Type B RCD around 10 years or so ago, when what is now in BS7671:2018 was first published.

Not being an electrician that is all rather over my head. The point has been made before, though, that charging with a 32A commando is not really different in principle than charging with a 3 pin plug UMC, but the regulations don’t apply to 3 pin. The current is higher for the commando but the voltage is the same. I suspect a lot more people charge using the 3 pin UMC than charge using a commando socket.

 

[Glan gluaisne]

Not being an electrician that is all rather over my head. The point has been made before, though, that charging with a 32A commando is not really different in principle than charging with a 3 pin plug UMC, but the regulations don’t apply to 3 pin. The current is higher for the commando but the voltage is the same. I suspect a lot more people charge using the 3 pin UMC than charge using a commando socket.

The slight risk from a PEN fault, if the wiring installation uses a protective earth (PE) that is provided via the incoming supply cable (a TN system, as distinct from a TT system where no PE is provided on the incoming cable) is exactly the same when using the UMC, regardless of the type of connector used or the charge supply current.

It's a risk that applies to any outdoor circuit that is connected to something conductive that may be easy to touch, and is a regulation that has been around for decades. The risk is because when outdoors, your feet may be connected to the local ground potential, yet the conductive parts connected to the incoming PE may be at a higher potential, due to a fault condition. Clearly, this isn't safe, hence the reason for providing a local earth, in the form of an earth electrode near the point of use, together with an RCD to sense any earth leakage (in reality it senses the imbalance between line and neutral nowadays).

As far as safety is concerned, charging a car from an outdoor power outlet is no different to powering a caravan, running power to a greenhouse, providing a temporary building supply, etc. The requirement for an outdoor circuit like this has always included the need to connect it as a TT installation, with an earth electrode near to the point of use and a double pole RCD to disconnect both live terminals in the event of a fault (both line and neutral are classified as live terminals, because the neutral can be at a different potential to local earth)..

The only change to this standard practice with vehicle charge points is a side effect of the way that the signalling system works. The low voltage Control Pilot (CP) conductor that is used for bidirectional signalling between the car and the charge point operates at +12V and - 12V, but uses the PE as the return path. This means that it can introduce a DC component into the earth leakage sensed by the RCD, and a quirk of the way that most RCDs work means that this DC component can change the threshold levels at which the RCD trips, or may stop it tripping altogether. This is why the requirements for additional protection for electric vehicle charge points was introduced in, I think, 2013 (it's definitely not a new requirement at all).

A fair few early EVs didn't create this DC blinding problem, as they used pretty dumb on board chargers that didn't use any signalling to the power outlet. These were no different to a caravan hook up point, in terms of safety, and only needed an outlet that could supply the required current and which had the same sort of protection as used for a caravan hookup. I believe even the original Tesla Roadster used a system like this. It was the widespread use of the J1772 charge point protocol, now included pretty much word for word in IEC61851, that created the need for the protection for EV charge points to be DC tolerant, hence the reason for the 2013 change.

 

[Sean.]

Perhaps worth making that clear, as the regs for a TT installation are not the same as those for TN, as the concern is primarily what happens if there's a PEN fault, something that obviously canny occur with a TT installation as there is no PEN. This was something that I guess your electrician took into account when completing and lodging the Part P installation certificate. The more onerous requirements in Section 722 specifically apply to a TN installation, which is now the most common type of installation in the UK as a whole.

Out of interest, where did you manage to source a 2 module Type B RCD? I've only been able to find wider ones, that are a PITA to fit into a small enclosure and leave room for anything else.

Just been speaking with my sparky about this, as we’re about to install a DC charger on a PME supply. He suggested to check if the charging unit has an integral DP safety cutout internally which monitors the neural and thereby negates the need for a local earth rod.

He later linked me to such units which are available externally:

https://www.rapidonline.com/Matt-E-SP-EVCP-T-1PH-32A-Connection-Unit-for-1x-1PH-32A-EV-Charger-65-3423

...or suppose could just bang in an earth rod for a tenner

 

[LongRanger]

The Juice Booster 2 unit that I’ll be using also has this - my Electrician was really interested in it as he didn’t realise such things existed having only seen the Rolec type units previously.

 

[Glan gluaisne]

More and more units are incorporating built in protection. The Zappi does, for example, and I believe others may do as well. The cost issue for anyone connecting to a TN supply that's not using a charge point with 3 pole disconnect and some form of PEN fault detection has never been the cost of the earth rod, it's always been the very high cost of Type B RCDs (typically they are around £150 to £200, last time I looked). The large size of Type Bs may also be an issue, as all those I've seen have been a lot wider than a standard DP RCD.

 

[Adopado]

More and more units are incorporating built in protection. The Zappi does, for example, and I believe others may do as well. The cost issue for anyone connecting to a TN supply that's not using a charge point with 3 pole disconnect and some form of PEN fault detection has never been the cost of the earth rod, it's always been the very high cost of Type B RCDs (typically they are around £150 to £200, last time I looked). The large size of Type Bs may also be an issue, as all those I've seen have been a lot wider than a standard DP RCD.

Are these too good to be true ... described as Type B? :
https://www.screwfix.com/p/wylex-32a-32ma-dp-type-b-mini-rcbo/4766x

ah, I checked and the RCD element is not type B ... confusing

 

[Glan gluaisne]

Are these too good to be true ... described as Type B? :
https://www.screwfix.com/p/wylex-32a-32ma-dp-type-b-mini-rcbo/4766x

ah, I checked and the RCD element is not type B ... confusing

RCBOs are often confusingly marked, as they almost always have the overload type rating marked clearly, and only show the residual current sensing as symbols, or in very small type. It's not helped by having letters used for both the overload rating type and the residual current type, makes things unnecessarily confusing IMHO.

For a charge point using an RCBO, then the overload current type would normally be a Type B and if it's being used with an earth electrode near the point of use for residual current protection then the residual current part also needs to be Type B. Most RCBOs will be Type B for the overload part, and either Type A, or maybe Type AC, for the residual current part, neither of which are suitable for use with a charge point, with its potential to have a DC leakage component.

The foolproof way is to look at the symbols that should be marked on the unit. If it's a Type AC it will have a sine wave symbol, it's a Type A it will have a half sign wave symbol in addition to the sine wave one, to show it has a pulsed AC capability and if it's a Type B it will have a sign wave, the pulsed half sign wave plus a solid straight line with a dashed straight line below it, denoting that it has a DC capability, in addition to AC and pulsed AC capabilities. This little signs have to be marked on any approved device, so are a pretty foolproof way of determining which type it is.