TN-S (and one of those garage questions you love - this time for an EV chargepoint)

[thegruf]

Hi,
Welcome to my domestic supply, the product of many electricians some qualified, some employed by builders over the years undoubtedly less so!

- can somebody please confirm if this is TN-S please (lead incoming cable)



Also, although I dont make a habit of looking at it - is this the correct way to do the earthing?
Looks like a just standard earth bonding strap (is that good enough?) and I thought this should go to the MET block not both ways to the MET and off to the CU directly. I guess it doesnt really matter impedance wise.

Warning - follow up question is about a garage

A long time back when the garage went up I was told to put a 4mm two core SWA over to the garage, which I duly did, but to be honest as the garage was only ever used as a store it never got wired up.

More recently as some other work was being done I put a much larger 16mm 3 core SWA feed over to the garage (only 1.2m from the house; total about 15m cable length to where the garage CU is planned) in anticipation of purchase of an EV (32A charge).

I assume even with the garage this close is is best to TT it, not export the earth.

Did wonder though whether to use the 4mm for the CU in the garage and just have the EV charge point direct, probably off a small CU added in the houseas the current board is already full (and yes the tails going to need upgrading fro m16mm to 25mm for those of you with sharp eyes)

Thoughts appreciated please.

 

[davesparks]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

Yes it's TNS
Can't see the clamp on the lead in any detail, some lead clamps are very similar to pipe clamps.
The 16mm 3core is sufficient to meet your bonding requirements so why would you want to not use the reliable TNS earth and use a less reliable TT?
Why do you think the tails need to be changed?

 

[Richard Burns]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

TNS supply, rather poor earth clamp but see it a lot, for the extra 300mm of cable I would have had a dedicated MET, but no real problem.
Use the 3 core 16mm² to supply the garage CU, since it is in place. Ensure it is fused down at the origin.
Extend the equipotential zone out to the garage, not really a major issue.
Make sure the charging point is in compliance with the IET regulations and guidance.

 

[thegruf]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

wow - that's quick replies folks, thanks.

So, as the garage is close no need to TT. Good, I can see that's preferred.

Figured as the tails to the CU are only 16mm, would be a good idea to get these upgraded to better cope with the load from the house +plus the new 32A load from the EV.

Was just figuring to get a 32A commmando type socket for the EV. Are there other IET regs I might be missing?
(I know you can get grants but too much hassle tbh and you get a meter that reports back to HM Govt who know enough about me already!)

After mixed experience with electricians and the only good one I ever used now emigrated to Oz, I want to make sure I get this speccd right this time, so I dont end up with a half baked job done.

 

[davesparks]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

Distance has got nothing to so with whether you use the TNS earth or a TT earth. The deciding factor is the requirement for equipotential bonding and the ability of the protective conductors to fulfil the requirement.
16mm 3 core used for single phase provides a protective conductor which meets the requirements for main bonding in your installation.

 

[thegruf]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

understood - thanks (though if the garage was far enough away ...)

So, is it possible to get 16mm into a plastic CU as will have a spare way now if I forget the 4mm, presumably with the swa terminated in a metal box?
or is my original thought about a separate small metal CU to terminate the swa split off from the meter tails with a henley block going to work better

 

[Richard Burns]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

I would suggest researching mennekes car charging sockets/plugs as most EV will have a dedicated type of plug and often a dedicated EV charging point, just get a supply installed initially until you know what system you are going to need.

Also have a look for IET code of practice for electric vehicle charging equipment installation.
Lot of fun stuff to take account of!

We cannot really provide a step by step guide to the installation as we have not seen it.
The installing electrician can decide on the method of SWA termination and the method of supply that best suits them.

 

[amlu]

Re: TN-S (and one of those garage questions you love - this time for an EV chargepoin

leave the plastic consumer unit alone, mount a small metal one next to it and terminate SWA in there. split the tails with a henley block.