Does the BEAMA guide stipulate that for EV installations on TT systems, the implementation of Type B or F RCDs is preferable over Type A RCDs ?

Don't know what Beama says but 7671 and COP says type B or type A plus 6mA DC leakage detection in the charge point, the latter is normal practice.

Alan B said:

There is a lot of discussion about EVCP not sharing a 30mA type A rcd with other circuits.

There is no discussion necessary here regards the 30 mA "sharing", it's not permitted by BS 7671 ... 722.531.3.101 says 'each charging point incorporating a socket-outlet or vehicle connector complying with the BS EN 62196 series shall be protected individually by an RCD of Type A, Type F or Type B and having a rated residual operating current not exceeding 30 mA."

The requirement says it all.

Alan B said:

But when that RCD/RCBO is then protected by an upstream 100mA or 300mA type A rcd along with other circuits, is it more tolerant to DC leakage current and by how much. Or should we be installing very expensive type B or type F RCD's.

Upstream RCDs need to be installed with reference to the currents they are protecting against. If the upstream RCDs are used to supply only charging points (and/or other loads) in which DC residual currents are unlikely, or if DC residual current protection is included in the charging points, then they also might be OK to be Type A or Type F.

Alan B said:

Had a bit of a look around this and from what I case see the 100mA and 300mA devices can only tolerate 30mA.

Again, this information is included in BS 7671 - see Regulation 531.3.2.

Glen,

Sorry made a mistake on previous post.  Should have said the 300mA or 100mA devices can only tolerate 6mA DC, therefore if other circuits are included in the sub DB, presumably in most cases there is likely to be additional DC leakage from those circuits. Most common would be a garage with LED lights and possibly a granny charger plugged in to a socket (I am seeing this more often in multi ev households). 

In scenarios like these, it is wise to select Type B or Type F

The question now makes sense.

This information, at least regarding smooth DC residual currents, is in 531.3.3.

AMK said:

In scenarios like these, it is wise to select Type B or Type F

Perhaps not Type F, which can only cope with 10 mA smooth DC.

But again, this is all in Notes in Regulation 531.3.3.

Certain manufacturers offer these devices at around £150 for a Type B RCD rated at 300 mA. That’s 5 x more than the type A equivalent.

AMK said:

Certain manufacturers offer these devices at around £150 for a Type B RCD rated at 300 mA. That’s 5 x more than the type A equivalent.

Agreed ... back in around 1988, I installed a single-phase 30 mA RCD (with rated current 63 A) in my Dad's (domestic appliance repair) workshop.

That would perhaps be described be a "Type AC without current isolation tests and EMC tests, and without some endurance tests (etc. etc.)".

The equivalent price today would, I believe, be around £300 inc VAT !!! Compare with the price of a current Type A !

If the upstream RCDs are used to supply only charging points (and/or other loads) in which DC residual currents are unlikely, or if DC residual current protection is included in the charging points, then they also might be OK to be Type A or Type F

Do we yet know if the d.c. components from EVs result from only faults, or could arise in normal service too? I'm thinking that if the EVSE incorporate 6mA RDC-DDs then we're protected from >6mA d.c. from that charge point - but if the submain is feeding say 3 charge points, and if the DC could arise from normal service, then the submain could be exposed to something just less than 3x 6mA and we're back to needing B-types again.

   - Andy.

My understanding from IET presentation is that they can can create up to 5mA DC leakage under normal operating conditions and the value can change depending on what car is connected. Therefore it can't be considered a fixed value. If we are looing at multiple charge points it's likely to be a commercial install and extra costs accepted.

But for private residential the industry is creating an expectation of  installation costs in the region of £300 to £400. Then I come long and say because of over head lines, TT earth and submains I need an extra £300 for type 1 spd, £250+ for type B RCD etc. I am sure many of the big companies will just chuck a EVCP in, no spd and single type A RCD/RCBO if you are lucky.