Power point in external glasshouse

[cliffed]

Client wants 2g socket in greenhouse, obviously IP rated,will be supplied from Rcd, the greenhouse consists of metal frame work on the ground.
Does this require MPBC

 

[cliffed]

Why TT, just run a 1.5mm^2 swa including the armour as CPC and bonding and it meets the regs.

Cheapest option

Except Pme supplies

 

[westward10]

If that is the new book I did wonder if it applied to all TN systems.

 

[cliffed]

If that is the new book I did wonder if it applied to all TN systems.

It’s in the new book but without looking @ the blue book I’m pretty sure it’s in there too.

 

[cliffed]

I doubt if I would take a Pme supply to the greenhouse anyway.
It just highlights the requirements & the expense, if done correctly the costs of adding a Power point

 

[westward10]

It’s in the new book but without looking @ the blue book I’m pretty sure it’s in there too.

It is there but is now amended.

 

[cliffed]

It is there but is now amended.

Cheers…can’t get to my book yet…having a new bathroom fitted, the house upside down @ the moment

 

[Julie.]

Except Pme suppliesView attachment 96674

No not except PME, it is except where PME conditions apply.


You should not be applying PME as the CNE will have been split at the header into L, N & E. You should never combine the N & E within the installation.


The note re except where PME conditions apply, was there over several versions of the regs, we would still apply the 50% or min 10mm^2 rule.

In fact there is no sizing for bonding within the (wiring) regulations where PME does apply!

This is usually determined by the utility themselves, and is often 50% or min 16mm^2 for customer service points, and generally 32mm^2 within the network (eg SNE sheath to CNE) even if its to one customer.

 

[cliffed]

No not except PME, it is except where PME conditions apply.


You should not be applying PME as the CNE will have been split at the header into L, N & E. You should never combine the N & E within the installation.


The note re except where PME conditions apply, was there over several versions of the regs, we would still apply the 50% or min 10mm^2 rule.

In fact there is no sizing for bonding within the (wiring) regulations where PME does apply!

This is usually determined by the utility themselves, and is often 50% or min 16mm^2 for customer service points, and generally 32mm^2 within the network (eg SNE sheath to CNE) even if its to one customer.

I don’t intend to combine N & E..never have…For me it’s gonna be a TT system @ the greenhouse.
Also the 10mm MPBC would apply if using the DNO earth

 

[westward10]

This has become somewhat confused I asked in #22 if this applied to all TN systems and whilst TN-C-S does not necessarily mean PME I was answered yes it does but it doesn't?

 

[cliffed]

This has become somewhat confused I asked in #22 if this applied to all TN systems and whilst TN-C-S does not necessarily mean PME I was answered yes it does but it doesn't?

Definitely not apply to TNS

 

[Julie.]

I don’t intend to combine N & E..never have…For me it’s gonna be a TT system @ the greenhouse.
Also the 10mm MPBC would apply if using the DNO earth

Where do you get the 10mm from?

If that's from table 54.8 or 544.1.1 then as per your wording - those figures are "except where PME conditions apply "

 

[Julie.]

This has become somewhat confused I asked in #22 if this applied to all TN systems and whilst TN-C-S does not necessarily mean PME I was answered yes it does but it doesn't?

I understood you to mean all tn conditions applicable to electrical installations beyond the utility supply point when I answered yes i.e. the area covered by the wiring regs; but fair enough, within the utility network the content of the wiring regs is not necessarily applicable.

 

[cliffed]

Where do you get the 10mm from?

If that's from table 54.8 or 544.1.1 then as per your wording - those figures are "except where PME conditions apply "

10mm on a TNCS/ PME supply where the Neutral size is 35mm <

 

[Julie.]

10mm on a TNCS/ PME supply where the Neutral size is 35mm <

Where do you get this from?

If it's table 54.8 or 544.1.1 then as per your wording - those figures are "except where PME conditions apply "

 

[cliffed]

Earthing systems recognised