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NewbieT

Active Member
Aug 16, 2019
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I'm afraid a Type B is necessary, as it's the status of the outlet that matters, as that's where the installation terminates. Any outlet that is intended for EV charging has to comply with the regs.

The RCBO linked to is only DC sensitive in the sense that it's a Type A, so able to deal with pulsed DC as well as AC. Unfortunately a leakage fault when charging may well be when the charge point is at State A, which is a steady +12 VDC on the Control Pilot, via a 1 kohm source impedance. This equates to a possible 12 mA of DC leakage to earth if the CP was shorted at the vehicle end under some sort of fault condition, hence the requirement to be able to detect a leakage fault in the presence of DC that may be greater than 6 mA.

The key thing to look for are the symbols on the RCD/RCBO, rather than anything in the description. This chart, lifted from Doepke, shows the symbols for each type at the top:

View attachment 591240

That’s not quite how I read 722.531.2.

RCD Type A can be used with either something like an O-PEN device or a charge point with the 6 mA protection built in.

B7804A3E-6AFB-4261-90BC-31069917C87B.jpeg
 

Glan gluaisne

Supporting Member
Sep 11, 2019
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That’s not quite how I read 722.531.2.

RCD Type A can be used with either something like an O-PEN device or a charge point with the 6 mA protection built in.

View attachment 591287

Exactly, but we're discussing charge points that do not have DC leakage protection built in and Commando connectors that also don't have any form of protection built in.

BTW, that section of the regs has been superseded by Amndt 1, with sub-section 722.531.2 removed and replaced with different wording in sub-section 722.531.3. The corrigendum is available from the IET, but in case you've not seen it, here's the text of the RCD section, plus I've attached a pdf copy of the corrigendum.

722.531.3 Residual current devices (RCDs)

722.531.3.1 RCDs shall disconnect all live conductors.

722.531.3.101 Unless supplied by a circuit using the protective measure of electrical separation, each charging point incorporating a socket-outlet or vehicle connector complying with the BS EN 62196 series shall be protected by an RCD having a rated residual operating current not exceeding 30 mA

Except where provided by the EV charging equipment, protection against DC fault currents shall be provided by:

(i) an RCD Type B, or

(ii) an RCD Type A or Type F in conjunction with a residual direct current detecting device (RDC-DD) complying with BS IEC 62955 as appropriate to the nature of the residual and superimposed currents and recommendation of the manufacturer of the charging equipment.

RCDs shall comply with one of the following standards: BS EN 61008-1, BS EN 61009-1, BS EN 60947-2 or BS EN 62423.

NOTE 1: Types of RCD are described in Regulation 531.3.3 in respect of their behaviour when exposed to DC components and frequencies.

NOTE 2: Requirements for the selection and erection of RCDs in the case of supplies using DC vehicle connectors according to the BS EN 62196 series are under consideration.

NOTE 3: An RCD Type A or Type F in conjunction with an RDC-DD can be arranged with the RDC-DD inside the EV charging equipment and the Type A or Type F RCD upstream in either the charging equipment or the installation.
 

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mr_e

Member
Dec 26, 2020
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This has been a very useful thread, many thanks for all the posts.

Could Option 1 and Option 2 be made cheaper by using a combination of Type A RCD + >6ma DC leakage detector, instead of a Type B RCD?

As that would avoid the high cost of the Type B RCD?

Is it even possible to buy a >6ma DC leakage detector as a standalone component?

And would another advantage be that it removes the need for any RCDs upstream of a Type B (if present) also needing to be converted to Type B?
 

Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,708
UK
This has been a very useful thread, many thanks for all the posts.

Could Option 1 and Option 2 be made cheaper by using a combination of Type A RCD + >6ma DC leakage detector, instead of a Type B RCD?

As that would avoid the high cost of the Type B RCD?

Is it even possible to buy a >6ma DC leakage detector as a standalone component?

And would another advantage be that it removes the need for any RCDs upstream of a Type B (if present) also needing to be converted to Type B?

The cost of a Type A plus some sort of DC tolerant detection module would be higher than the cost of a Type B, I'm sure. A Type B is about £114, the cheapest DC tolerant detection module I know of is around £50, but requires additional circuitry, a contactor, etc in order to work, push the cost up over £100, plus there's the cost of the Type A on top of that (needed because there has to be a manual reset - the module resets if power cycled, so it non-compliant on its own.

Avoid connecting RCDs in series if at all possible, as there is a need to maintain selectivity. Charge point RCDs should be connected to the non-RCD protected side of the incoming supply, either with short (less than 3m from the main fuse) tails to a Henley block on the incoming supply or via an MCB protected way in the main CU. It's preferable, IMHO, to always connect to the tails if possible, as this avoids heat buildup in the main house CU (drawing 32 A continuously through an MCB for hours on end will cause it to warm up a fair bit).
 

Glan gluaisne

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Sep 11, 2019
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This ev charge unit appeared on eBay and has pen fault built in so no earth rod needed. Also it's 18th edition.

No sure on quality but it seems a nice small neat package. Similar to the EO mini and QUbev

7KW EV Car Charger No Earthing Rod Required 18th Edition Compliant + KEY LOCK | eBay

Looks to be good value. My guess is that, like the Qubev unit, it may well use the Viridian EVSE module, as that has both open PEN and DC tolerant earth leakage protection built in. If so, then there's no issue over quality, the Viridian modules are pretty well made. All an EVSE like that would need would be a supply with over-current protection plus a Type A RCD, so it would make for a pretty cheap installation for anyone unable to claim the OLEV grant.

Overall, that would be a better solution than messing around with a 32 A commando outlet, plus open PEN protection and a Type B RCD, IMHO. Apart from anything else, any EV could charge from it, making it a bit more future proof than a commando outlet.
 

mr_e

Member
Dec 26, 2020
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0
London
Looks to be good value. My guess is that, like the Qubev unit, it may well use the Viridian EVSE module, as that has both open PEN and DC tolerant earth leakage protection built in. If so, then there's no issue over quality, the Viridian modules are pretty well made. All an EVSE like that would need would be a supply with over-current protection plus a Type A RCD, so it would make for a pretty cheap installation for anyone unable to claim the OLEV grant.

Overall, that would be a better solution than messing around with a 32 A commando outlet, plus open PEN protection and a Type B RCD, IMHO. Apart from anything else, any EV could charge from it, making it a bit more future proof than a commando outlet.

Super useful, thanks a lot for this
 

Glan gluaisne

Supporting Member
Sep 11, 2019
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I've updated the first post in this thread in the light of other options that are now available. I can't edit it, so have copied an edited version of that initial post below:



There's been debate about the cheapest way to install a charge point, if not able to take advantage of the OLEV grant (or just if you don't want a smart charge point). I thought I'd try and cost the materials, excluding labour, for a few options. To allow a fair comparison I've assumed a 10m cable run from the incoming supply point to the charge point location, and assumed that SWA cable will be required (it may or may not, depends on the location). All options assume that the incoming supply to the house is TN (either TN-C-S (PME) or TN-S). If the house has a TT supply (only usually applies to older, rural, properties now) then the prices will be different. All options assume that charging at 32 A is required.

Option 1 is to charge using the Tesla supplied UMC, together with the optional 32 A Commando adapter lead, connected to a 32 A interlocked Commando outlet. Protection is via a 40 A Type B RCD, with a 40 A MCB for over-current protection, with an earth electrode being installed close to the vehicle charging point location. Total cost of all materials, including the Tesla 32 A Commando adapter needed, is ~£310 inc VAT

Option 2
is as above, but using an O-PEN device, rather than an earth electrode. Total cost of all materials ~£390 inc VAT

Option 3 (new)
is as above, but using an Ecoharmony connection box, that includes open PEN, DC tolerant earth leakage protection and over-current protection, so can be connected directly to the incoming tails, via a Henley block, with a suitable cable. Total cost of all materials is ~£354 inc VAT

Option 4 uses the cheapest non-tethered charge point I could find, the Qubev unit, that has a Type 2 outlet, plus variable charge current via a switch on the side. This option still requires an earth electrode to be fitted to provide open PEN protection. This charge point does avoid having to use the UMC supplied with the car, plus the Commando adapter lead, and can be used with the Type 2 lead supplied with the car. If this is installed with an earth electrode etc, as per Option 1 above (essentially just swapping the interlocked Commando for the Qubev charge point) then the total cost of all materials comes to ~£459 inc VAT

Option 5 is the same as option 4, but uses an Ecoharmony connection box to provide over-current, DC tolerant earth leakage and open PEN protection. No earth electrode is required for a PME installation. Total cost of materials comes to ~£539 inc VAT

Option 6 is the same as Option 4, but uses the version of the Qubev that has 18th Ed Amdt 1 protection, so avoids the need to use a Type B RCD. It does still require an earth electrode if connected to a PME supply. Total cost of materials comes to ~£426 inc VAT

Option 7 is the same as Option 6, but uses an O-PEN device instead of using an earth electrode. Total cost of materials comes to ~£506 inc VAT

Option 8
is to use an EV Power Pod non-tethered charge point, with integral DC tolerant earth leakage and open PEN protection, plus a 40 A RCBO in an enclosure near the supply point. Total cost of materials comes to ~£466 inc VAT The charge point is available from here, for £360 inc VAT: 7KW EV Car Charger No Earthing Rod Required 18th Edition Compliant + KEY LOCK | eBay


The price of the Ecoharmony connection box, including open PEN, DC tolerant earth leakage protection and a 40 A RCBO is ~£242 inc VAT, from here: EVSE Connection Centre with PEN Loss detection - IP65

Best price for a 40 A Type B RCD I can find is £114 inc VAT, from here: Type B RCD / RCCB 40A for EV Charge Point Installations. 2 pole, single phase, 30ma. 40 Amp

The same supplier offers a metal enclosure, fitted with this RCD, together with both a 40 A and 6 A MCB, for £179, which is perhaps £20 more than the cost of the individual parts, but looks to be a neat enough option.

All the prices above include the cost of Henley blocks, a metre of tails, cable glands, cleats, short lengths of additional CPC, etc.

Overall, the cheapest option is to install a 32 A interlocked Commando, although that option means using the UMC supplied with the car, plus the optional 32 A Commando adapter, all the time. This has the advantage of having a "Tesla button" on the connector, but the disadvantage that the UMC will need to be supported on something, as it can't safely hang from it's lead for long periods, I think.

Labour will vary a great deal depending on location and how easy it is to run cables etc. Around here a typical day rate for an electrician is now around £220, plus VAT in most cases. A typical installation shouldn't really take longer than about half a day, although it would be normal to charge more than just half a day's labour, unless the person had another small job to go to for the other half of the day.

Smart charge points, as required in order to claim the OLEV grant, are more expensive, with a total material cost of typically £200 or so higher than the costs above.

To summarise the above, the two cheapest options are to fit an interlocked 32 A commando, protected by either a Type B RCD, 40A MCB and earth electrode, or protected by an Ecoharmony connection box.
 
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banned-66611

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If you have a look around some electricity suppliers are doing deals on cheap installations. You can switch to them for a couple of months, get the install and switch away again.
 

Glan gluaisne

Supporting Member
Sep 11, 2019
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If you have a look around some electricity suppliers are doing deals on cheap installations. You can switch to them for a couple of months, get the install and switch away again.

Agreed, but these examples were specifically for the case where OLEV grant funding was not available, and all the cheap deals rely on the installation being eligible for grant funding.
 

FabB

Member
Oct 23, 2020
11
0
London
Hi Glan,

Could be please advice us the cheapest way to get 11 Kw charger, we have 3 phase at work, it's for Tesla 3 SRP, 2021

Thankls
 
Jan 10, 2021
58
32
Andover
Moderator comment - post merged from "Commando 32a vs dedicated EV charger?"

Hey,

I've got my my model 3 pick up this Friday and I had a question about home charging.

Im going to be predominantly charging at work. I currently have an outside socket at home, where I can charge if needed currently but at the slow 10mph.

I was looking at options and think a commando 32a might be more cost effective than a full EV charger installation.

Can anyone tell me the difference between the two? I'm not that fussed on the "smart features" as I'm not always going to be charging at home. Would just like a little faster charge when I need it.
Anyone know a rough install cost of a commando 32a?

Thanks!
 
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Glan gluaisne

Supporting Member
Sep 11, 2019
2,782
2,708
UK
I detailed this option in this thread, options 1 and 2 in the first post (repeated in post 29 above) are the materials cost for installing a 32 A interlocked commando. Labour costs would be broadly the same for installing either a commando outlet or a charge point.
 

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