Earth rod needed for shed supply or pme allowed ????

[Toneyz]

I never in 40 years of my working life asked for advice from any scheme.

Only had dealings with NICEIC via the previous so-called electrical contractors I worked for, spoke to their technical helpline on a few occasions and I found them extremely knowledgable

 

[Strima]

Only had dealings with NICEIC via the previous so-called electrical contractors I worked for, spoke to their technical helpline on a few occasions and I found them extremely knowledgable

Spoke to the NIC tech helpline on Friday for a sanity check and he knew the reg number straight off the top of his head before I'd even finished speaking.

 

[oracle]

You can use two RCD's, one type S at the CCU protecting the supply to the shed and normal RCD protecting the shed final circuits. This will give you discrimination between the two

 

[Strima]

You can use two RCD's, one type S at the CCU protecting the supply to the shed and normal RCD protecting the shed final circuits. This will give you discrimination between the two

What if the RCD in the CU is providing additional protection for other circuits?

 

[oracle]

Obviously I would use RCBO to supply the shed. I don't use split boards, I use breakers and RCBO's as suitable for each circuit.

 

[Nigel]

You can use two RCD's, one type S at the CCU protecting the supply to the shed and normal RCD protecting the shed final circuits. This will give you discrimination between the two

Why would you need a Type S? RCD?

 

[oracle]

BS7671 Regulations 314.1(iv)and 531.2.4 require installations to be subdivided into circuits to prevent accumulated protective conductor currents causing unnecessary tripping of RCD’s. Where there are RCD’s in series for Additional Protection, then Selectivity must be provided to comply with Regulation 536.3.
This can be provided by the use of Type S RCD’s which will provide a time delay to allow for a lower rated RCD down stream of the main RCD to operate first under fault conditions.

 

[Nigel]

BS7671 Regulations 314.1(iv)and 531.2.4 require installations to be subdivided into circuits to prevent accumulated protective conductor currents causing unnecessary tripping of RCD’s. Where there are RCD’s in series for Additional Protection, then Selectivity must be provided to comply with Regulation 536.3.
This can be provided by the use of Type S RCD’s which will provide a time delay to allow for a lower rated RCD down stream of the main RCD to operate first under fault conditions.

That does not answer my question.

 

[westward10]

Isn't that the 18th, too lazy to look.

 

[Dillb]

BS7671 Regulations 314.1(iv)and 531.2.4 require installations to be subdivided into circuits to prevent accumulated protective conductor currents causing unnecessary tripping of RCD’s. Where there are RCD’s in series for Additional Protection, then Selectivity must be provided to comply with Regulation 536.3.
This can be provided by the use of Type S RCD’s which will provide a time delay to allow for a lower rated RCD down stream of the main RCD to operate first under fault conditions.

That does not answer my question.

@oracle didnt quote you

 

[Nigel]

@oracle didnt quote you

Agreed. Thank you.

 

[oracle]

Reason I didn't quote you is I wasn't addressing it to you, simply posing an axiom. If you don't know about Type S RCD’s, I suggest you research them, along with the other types as well. BSEN 61008 and 61009 are not the only RCD’s out there.

 

[Nigel]

@oracle didnt quote you

Agreed. Thank you.

Reason I didn't quote you is I wasn't addressing it to you, simply posing an axiom. If you don't know about Type S RCD’s, I suggest you research them, along with the other types as well. BSEN 61008 and 61009 are not the only RCD’s out there.

I know all about Type S RCDs.

Again, why would the distribution circuit feeding the CU in the shed need a Type S RCD protection. You are the one saying to use it but cannot back it up.

 

[petermouse]

On this subject I recently spoke to an electrician who was repairing a street supply cable under the pavement. He agreed that out buildings should be TT’d. Because when a supply cable is repaired the tendency is to make it Tncs connecting the earth to the neutral to get better Ze readings. So a property with an apparent tns at the supply end may well be a tncs. Also on the subject of on a completely wooden/plastic construction no extraneous metal parts, then allowing the installer to extend the local earth to it. No mention is made of the danger of using class 1 equipment in this environment. I feel the more I read the less I actually know.

 

[Wilko]

... I recently spoke to an electrician who was repairing a street supply cable under the pavement. He agreed that out buildings should be TT’d. Because when a supply cable is repaired the tendency is to make it Tncs ...

Hi - supplies that present at the installation origin as TNCS (with or without PME) can be extended to outbuildings. The means of earthing at the origin can be reused at the outbuildings, it just needs to be properly designed. So my 20p worth is Mr StreetSupply is wrong .

 

[FatAlan]

I have a couple of out buildings total run about 50m which were fed by suspended 4mm T&E from RCD protected CU at house. Each shed CU was/is rodded. In the process of swapping to buried 6mm SWA on seperate MCB protected circuit with RCBOs at shed. Will use PME but also keep rods. This brings up old discussion that DNO engineer when converting a TT to PME advised that the rod be disconnected as it can cause nuisance tripping. I did leave it in place with no problem.

 

[oracle]

Agreed. Thank you.


I know all about Type S RCDs.

Again, why would the distribution circuit feeding the CU in the shed need a Type S RCD protection. You are the one saying to use it but cannot back it up.

Told you already, I was posting an axiom also told you before you appear to be a Troll. I will not respond to anything you post in future, so please don't tell me that I haven't answered your questions. I won't!

 

[Strima]

This brings up old discussion that DNO engineer when converting a TT to PME advised that the rod be disconnected as it can cause nuisance tripping.

That's where I've been going wrong, just remove the earth and your problems go away...

 

[Midwest]

Wasn't the 18th draft proposing rodding (pardon me) all PME or TNC-S supplies?

 

[Strima]

Wasn't the 18th draft proposing rodding (pardon me) all PME or TNC-S supplies?

It did but never got written in, it will probably be in the 1st amendment.