Cenex report on EV chargers

[Murdoch]

Ok all, anyone else got a copy of this report?

makes interesting reading, especially as they appear to do random checks of installs which OCS CPSs should learn from

one thing that caught my eye is that they say Hituff should have mechanical protection outside.... which I’m not sure I agree with.

then the analysis on pricing - well the UK is a large landmass and cost vary A LOT - so why do they even mention it! It’s none of their business

thoughts?

 

[Sharpend]

Link? 

 

[Murdoch]

Link? 

I've got a copy but its far to big to upload here. 

PM me with an email address and I'll send you a copy?

 

[Phoenix]

one thing that caught my eye is that they say Hituff should have mechanical protection outside.... which I’m not sure I agree with.

I agree with you, generally it doesn't needs it, although there are possibly a few instances where the risk of damage means it probably does need it (or more likely, a better route for it finding). And likeise underground would require it (but better to just pick SWA instead). So while you could come up with some situations where you could deem it necessary, you'd change something else instead. The only time I can think of where you might want to install it in machanical protetcion is somewhere like a warehouse, where its all wired at high level on tray, but you drop down the walls in galv conduit.

Anyway, back to EVSE. They go on about Hi-Tuff but seem to miss SY out. Putting asside the big question mark over its use in installations under BS7671, it certainly cant be used outdoors unless in containment, the sun gets to the sheath, which at first goes a misty white, then it starts to crack and moisure gets in, braid rusts, and you are left looking at a horrible brown thing in a misty white covering.

 

[Murdoch]

I agree with you, generally it doesn't needs it, although there are possibly a few instances where the risk of damage means it probably does need it (or more likely, a better route for it finding). And likewise underground would require it (but better to just pick SWA instead). So while you could come up with some situations where you could deem it necessary, you'd change something else instead. The only time I can think of where you might want to install it in mechanical protetcion is somewhere like a warehouse, where its all wired at high level on tray, but you drop down the walls in galv conduit.

Anyway, back to EVSE. They go on about Hi-Tuff but seem to miss SY out. Putting aside the big question mark over its use in installations under BS7671, it certainly cant be used outdoors unless in containment, the sun gets to the sheath, which at first goes a misty white, then it starts to crack and moisture gets in, braid rusts, and you are left looking at a horrible brown thing in a misty white covering.

Yes - VERY odd. 

IMHO Hituff is ideal for use on walls, but not underground. Shame the report seems to have broad brushed Hituff as questionable or even unacceptable , but not even commented about SY - makes you wonder about the competence of the people who did the audits.

I've only skim read it, but when I get a chance I'll print it and read it more thoroughly

 

[UNG]

Read that report and it seems to have a lot of padding in some areas, whether it was necessary or was done to justify the cost is open to debate

It certainly highlights some interesting points although the meticulous analysis for me fails in some parts.

Given the number of installation issues noted it would have been interesting to see a break down of of installers by CPS given Certsure's involvement in the audit and possibly having a conflict of interest

While analysing the costs it would of been interesting to see some analysis of the distance between CU and EV outlet / approx circuit length

Again on cost analysis how many of the higher cost installs included remedial work to the installation to enable installation of EV point to the regulations in force

A point of concern for me would be that if the small audit sample is representative of all the installations carried out then there is the potential for a significant number of unchecked non compliant EV points some of which could be dangerously unsafe

 

[Phoenix]

I'm just trying to get the RCD situation straight in my head; My undertstanding of this is thus,

*Type AC RCDs are not allowed as they can be locked by very small amounts of stray DC, so you can't have the sole RCD protecting the EVSE being a type AC, fair enough.

*Type A RCDs arn't so easily locked by DC, but still can if the current if over 6mA, so you can use a type A if the device is internally protected by device that cuts off if more than 6mA leaks

*Type B RCDs are pretty much immune to DC locking, there if the EVSE does not cut off with over 6mA of leakage, then RCD protection must be type B

I think thats pretty much standard, but going onto interpret it against some situations you come across.

If the supply has to be from an RCD shared with other circuits, say if you had a dual split board with two type AC rcds, So you come off that and feed through a separate type A RCD because the unit has internal protection against over 6mA DC leakage, is that ok? My view is that its not, because a fault could occur and the EV leaks say 4mA, the DC leakage module doesn't trip in, the type A RCD for the charger is still functional, but its a 30mA Device and 4mA isn't going to trip it. The type AC device has 4mA of DC leakage, and it *may* be locked.

I'm not sure how feasible it is to lock a type AC device with only 4mA of leakage, gut feeling says you'd probably need a bit more to saturate the core, but its an unknown

 

[Risteard]

No it isn't acceptable to have a Type AC RCD upstream of a Type A or B device (or Type A upstream of a Type B). 

Also the RCD must be dedicated to the EVSE. Multiple EVSEs may not be protected by the same RCD, nor may other parts of the installation be protected by the same RCD as any EVSE. 

 

[Murdoch]

No it isn't acceptable to have a Type AC RCD upstream of a Type A or B device (or Type A upstream of a Type B). 

Also the RCD must be dedicated to the EVSE. Multiple EVSEs may not be protected by the same RCD, nor may other parts of the installation be protected by the same RCD as any EVSE. 

hum

the last 3 I looked at had

1. circuit with no rcd protection

2. circuit with standard type b rcbo

3. circuit with standard dual rcd configuration

is it me or aren’t people doing this correctly?

 

[Risteard]

hum

the last 3 I looked at had

1. circuit with no rcd protection

2. circuit with standard type b rcbo

3. circuit with standard dual rcd configuration

is it me or aren’t people doing this correctly?

Undoubtedly plenty of installations are being done incorrectly. Hopefully those who have completed training on these are installing correctly as they cannot plead ignorance. 

 

[Murdoch]

Undoubtedly plenty of installations are being done incorrectly. Hopefully those who have completed training on these are installing correctly as they cannot plead ignorance. 

you wish !

its like solar connected in to dual rcd boards .... a very common sight

 

[Murdoch]

Last year I was asked by a customer to get a 2nd board in ready for a chargemaster installation.

On their specific request I fitted a "type A RCBO C32 " in the little CU ready for them

 

[Geoff1946]

ts like solar connected in to dual rcd boards .... a very common sight

Please enlighten me.

I had a solar system professionally installed a few years ago  On my dual split panel it's the only GE MCB on my otherwise  MK installation, and it is on the lightest loaded RCD.  The solar works OK.

The MCB mismatch did annoy me but I didn't actually complain. What is the perceived problem?

The only thing I have noticed is that if the RCD is tripped whilst the invertor is running at "full throttle", on a sunny day, there seems to be a surge. I say this because I did it once by accidentally touching a neutral to earth on a lighting circuit, resulting in blowing both tubes of an insectorcutor which is on an associated circuit on the same RCD.

Should the invertor have been put on an RCBO, on its own?

 

[Murdoch]

^^ 

solar can continue outputting 230 for up to 5 seconds AFTER the RCD trips so somewhat defeats the point of the RCD

 hence why you shouldn’t connect solar to a rcd shared with other circuit’s 

 

[Phoenix]

Some will counter that with that with its a standard DP RCD, then once its tripped, you are left with a separated supply for those five seconds so your fault path to earth has been broken anyway.

I think theres something that makes it worse as well, obviously when the solar is outputting, part of the current to run the load comes from the inverter with the grid making up the rest, lets say its a 50/50 at one partiuclar moment in time. 1kw being prooduced by the solar, and 1kwcomming from teh grid because there is a 2kw load. Surely the fault current will divide in the same way, so if you have 30ma running to earth, then 15ma from the grid, and 15ma from the inverter, only the first of those is comming through the RCD, so is it now effectivly a 60mA RCD? Though with the neutral link only the grid side is that actually true? I think I need to sit down and draw it out with good old Mr. Kerchoff.

I think we can all agree its a shoddy installation practice though, as is mixing and matching breakers

 

[Risteard]

I forgot to mention that an EVSE RCD must break all live conductors.

 

[Phoenix]

I'm just trying to work out that the logic for that being a requirement, I'm guessing its related to a fault on the supply network that lets the neutral rise up against ground voltage, and at the same time another fault that allows that neutral to be contacted, so neutral->earth fault to a car thats on a charger thats quite likely on a TT system. The electrode will pull down the touch voltage put not to safe levels, But the change of the two faults at once, pretty damn slim as when it first occurs the car will be tripping out the RCD in every supply point used, so would be repaired. So its only just occured, and then a supply issue occurs?

 

[Murdoch]

Having a DP rcd won’t help you if it trips, because the solar inverter will still be delivering 230v to the disconnected side of the RCDs and therefore all the load circuits

 so if you’re touching a live conductor, the rcd will cut off the mains but NOT the invertor input to the CU  until it stops delivering 230 v

 if you’re frail, it’ll be to late to worry about the up to 5 second cut off 

that’s why having solar is , in certain situations, so dangerous on a dual or single rcd board

 

[Phoenix]

 so if you’re touching a live conductor, the rcd will cut off the mains but NOT the invertor input to the CU  until it stops delivering 230 v

 if you’re frail, it’ll be to late to worry about the up to 5 second cut off 

Yes, but it'll only be 230v with respect to neutral, not earth for the rest of those 5seconds, as once the RCD trips the earth reference is gone and you effectivly have a 230v electrically separate supply in the same way a shaver point is.

I'm not saying its ok, I'm just saying its probably not quite as dangerous as it sounds when you say it quickly

 

[Murdoch]

Yes, but it'll only be 230v with respect to neutral, not earth for the rest of those 5 seconds, as once the RCD trips the earth reference is gone and you effectively have a 230v electrically separate supply in the same way a shaver point is.

I'm not saying its ok, I'm just saying its probably not quite as dangerous as it sounds when you say it quickly

How do you work that out.

The CPC's should always be connected or am I missing something?