18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Discussion of charging at home and at work.
mwinlow
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18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Postby mwinlow » Sun Nov 04, 2018 12:05 pm

I am given to understand that as of Jan 1st 2019 the 18th edition of UK Wiring Regs stipulate that *all* electric vehicle charging points (EVSEs) must be protected with a 'Type B RCD" where the 'Type B' relates to the sensitivity of the RCD to AC, pulsating AC *and steady DC leakage currents*. Current regs are covered by the use of easily and cheaply available 'Type A' RCDs (usually in the form of an RCBO which combines the attributes of the RCD with those of an MCB - miniature circuit breaker - which provides over-current protection). If you try to find a 'Type B' RCBO online, good luck. The only ones I could find cost over £300! Obviously, this is all going to mean, at a stroke, a *doubling* of the cost of an EVSE.

Or have I got it all completely wrong (not for the first time)?


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Neil
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Re: 18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Postby Neil » Tue Nov 06, 2018 9:15 pm

Some 'help' here. https://www.voltimum.co.uk/articles/evse-rcd-protection-and-18th-edition and here https://www.voltimum.co.uk/articles/ev-charging-and-rcd-selection. Which comes from Doepke, http://www.doepke.co.uk/download/Techpub-06.pdf

So it doesn't have to be a Type B, but a DC disconnect function is a requirement. Retrofit options are mentioned, but I cannot find them for sale.

The bottom line appears to be that the answer will be yes.

I have asked Rolec if their offerings are compliant. I'll update if or when they reply.
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Martin Lee
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Re: 18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Postby Martin Lee » Thu Nov 08, 2018 2:27 am

Chunkybuns wrote:https://www.screwfix.com/p/wylex-32a-sp-type-b-mcb/55617#_=p

This is a link to a type B MCB. There are four types of MCB A, B, C, D. The current rating in Amps specifies a relatively slow over current protection for the device which will operate at a low multiple of the rated current due to the thermal effects of the current in the MCB. The different letters specify and much quicker trip of the CB at larger multiples of the rated current, I cant off the top of my head remember the numbers but they could be

A 3 times rating
B 6 times rating
C 10 times rating
D 15 times rating

for most uses type B is acceptable.

the type B RCD is a quite different device.

Martin Lee
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Re: 18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Postby Martin Lee » Thu Nov 08, 2018 3:01 am

obviously there is a question about the device, but a bigger question is do the chargers on the cars already meet a requirement to produce less than 6mA DC, I rather expect that those that do only do it by chance. Getting a car manufacturer to confirm that they comply with the requirements of BS EN 61000-3-2 so that a car can be plugged in without reference to the DNO proved impossible while I worked in the industry. I don't know if anyone has managed to do it yet or not.

Small scale PV manufacturers were concerned with the 20mA DC limit on sub 16A PV inverters in G83 being extended to larger PV inverters, and after a fair bit of time a compromise of 2.5mA per 1A of rated current was agreed upon. So a 32A output single phase inverter could produce up to 80mA of DC current. This still applies to the latest generation connection code G99.

9.4.6 DC Injection

9.4.6.1 The effects of, and therefore limits for, DC currents injected into the Distribution Network is an area currently under investigation. Until these investigations are concluded the limit for DC injection is less than 0.25% of the AC rating per Power Generating Module.

I would be surprised if car manufacturers rectifiers were so much better than PV manufacturers thought that they could manage.

I can see quite a few problems with older cars and new charge points installed to meet the requirements for detection of DC post 1st January 2019

Presumably some one checked that modern cars coming off the production line now do meet the requirements to produce less than 6mA of DC leakage.

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Neil
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Re: 18th Edition Wiring Regs - EVSE 'Type B' RCD Requirement

Postby Neil » Thu Nov 08, 2018 11:48 pm

Rolec replied.

As of January 2019 all of their offerings will be compliant with a Type B RCBO (or component combo) with a a 6mA DC sensitivity. They didn't respond on price. My current Rolec has a Type A EV (6mA) RCBO in it. (So it says on the device).

As some of these devices are rather specialised, prices will have reflected low demand. So the price will drop. As Martin says, hopefully someone will have checked that the manufacturers will be able to meet this. It's been coming for a while, so they have had plenty of warning.

The existing Code of Practice for EVSE installation (2nd Edition 2016) refers to:
BS7671:722.531.2 RCDs: The RCD protecting the chargepoint shall be at least a Type A RCCB complying with BS EN 61008-1 or RCBO complying with BS EN 61009-1. If it is known that the d.c. component of the residual current exceeds 6mA then a Type B RCD complying with BS EN 62423 shall be installed.


Which would suggest that the vehicle manufacturers have largely announce that they do not exceed 6mA DC. Interesting that Tesla recommend Type A suggesting that they see no DC risk exceeding 6mA

Some Type A devices saturate under steady state DC residual currents, so will potentially not operate for actual faults. Looks like this is at least in part to legislate for that. Type A also will not trip for steady state DC, only pulsing DC residual currents. Type B copes with most applications with rectifiers or inverters, but isn't necessarily best suited to many others.

Type B RCDs trip at >30-40mA smooth DC. Type EV trips at >6mA. It is acceptable to use a Type A device if a DC detection and tripping device rated 6mA DC is included. Doepke make such a detection and tripping device, but if anyone can find it for sale......

Type B appears to be the norm for Mode 4 and public charging stations, so should not adversely affect users.
Which would suggest the vehicle manufacturers have had fair warning.

There is no requirement to retrofit existing installations have grandfather rights.

More notes.http://www.doepke.co.uk/download/Techpub-08.pdf

The terminology is a bit loose, but:
RCD Generic term for a fault breaking device operated by residual current (I∆n), common formats include RCCBs and RCBOs.
RCCBs (EN61008) do not include short circuit and overcurrent protection, must be provided by external fuses and or MCBs.
RCCBs are manufactured in ratings <125A with a wide variation in sensitivity and Types.
RCBOs (EN61009) include short circuit and overcurrent protection, but are normally limited by their characteristics to final
circuit protection applications < 50A.
CBRs (EN947-2 Apx. B) MCCB with an in-built residual current protection module for applications >100A.
Neil Swanson
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mwinlow
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18th Wiring Regs - Electric Vehicle EVSE (Charging Point) 'Type B' RCD Requirement

Postby mwinlow » Sun Nov 11, 2018 9:23 am

I am given to understand that as of Jan 1st 2019 the 18th edition of the Wiring Regs stipulate that *all* electric vehicle charging points (EVSEs) must be protected with a 'Type B RCD' where the 'Type B' relates to the sensitivity of the RCD to AC, pulsating AC *and steady DC leakage currents*.

Assuming the above is correct, would anyone care to suggest a source for 2-pole and 4-pole 16A and 32A RCBOs that comply with the above which won't, at a stroke, *double* the cost of an EVSE?

Martin Winlow.

chris1982
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Re: 18th Wiring Regs - Electric Vehicle EVSE (Charging Point) 'Type B' RCD Requirement

Postby chris1982 » Sun Nov 11, 2018 5:40 pm

If you installation is existing I doubt you will need to change the breaker


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