Exporting PME to garage

[peteelecs]

Please canyou help I am a bit confused about the earthing to a shed if the house is PME can I just run an earth from the MET to the shed or can I only do this if house is TNS.How do i get earth to shed if its PME hope this doesnt sound to confusing any suggestions would be appreciated

 

[Deleted member 9648]

dunno about exporting earths. my missus says if i spend all day on this forum, she will export me and the PC to the garage!

........

 

[pushrod]

dunno about exporting earths. my missus says if i spend all day on this forum, she will export me and the PC to the garage!

Hey telectrix, you get my vote for the (intentionally) funniest poster on here
(there are are a few who make me smile when it's not intended!)

 

[trebor]

A garage will prob have a concrete floor then an issue is that the garage may be damp, have incoming services etc.
In which case you would not export a PME/TN-C-S house earth from the house, you would make the garage a TT install with earth rod

You are right to point out the damp floor situation which was known as an area of increased risk in my days as an installations inspector, what has not been mentioned so far on this long discussion is that the electrician has now been duckshoved the legal responsibility of using pme safely since the demise of the inspector, I say legal as it is the ESQCR who impose the pme regs and lets not forget that this is statutory document which every contractor should be aware of and possibly one that could be used against him/her as a duty holder

 

[Deleted member 9648]

You are right to point out the damp floor situation which was known as an area of increased risk in my days as an installations inspector, what has not been mentioned so far on this long discussion is that the electrician has now been duckshoved the legal responsibility of using pme safely since the demise of the inspector, I say legal as it is the ESQCR who impose the pme regs and lets not forget that this is statutory document which every contractor should be aware of and possibly one that could be used against him/her as a duty holder

In the kind of domestic situation discussed here the key document is bs 7671.....as long as the installing electrician complies with that he has met his responsibilities.

 

[jamesb1]

hi everybody can i clear a few points up a friend has asked me to wire up his garage/workshop . i have had a look over the job which i was going to install a metal clad db . reason being so i can gland the armoured in and metal clad sockets for mechincal protection and the feed with a 3core swa cable from the db in the house which is not rcd protected but i can fit a rcbbo to hager db to protect the cable and all the circuits the garage construction is breeze block and gurder its 10meters from the house its more like a workshop to be honest is my method wrong ? oh yes the house earthing sytem is pme


thanks james

 

[pushrod]

hi everybody can i clear a few points up a friend has asked me to wire up his garage/workshop . i have had a look over the job which i was going to install a metal clad db . reason being so i can gland the armoured in and metal clad sockets for mechincal protection and the feed with a 3core swa cable from the db in the house which is not rcd protected but i can fit a rcbbo to hager db to protect the cable and all the circuits the garage construction is breeze block and gurder its 10meters from the house its more like a workshop to be honest is my method wrong ? oh yes the house earthing sytem is pme

thanks james

You don't need to protect the distribution cable to the garage with an rcd as it is already has mechanical protection
, just use a submain with an rcd in.

 

[jamesb1]

ok thanks for that i just thought it would be easier to protect to whole thing from the house as i need a breaker for it and the just fit a dp mian switch at the garage db, and mcbs but can i use a metal clad db and sockets with a pme earthing system and the breeze block building with gurder type construction ?????????????????????

 

[pushrod]

structural steel should be bonded.

 

[jamesb1]

no probs there mate does that need to be a seperate earth back to the main earth terminal 10m/2 or can a spare core be used within the armoured if say a 4 core was used what about pme being used to earth a out building

 

[IQ Electrical]

no probs there mate does that need to be a seperate earth back to the main earth terminal 10m/2 or can a spare core be used within the armoured if say a 4 core was used what about pme being used to earth a out building

If you use the suppliers earth, your distribution circuit will have to be sized as a combined CPC and main protective bonding conductor and sometimes this is a better reason for making an outbuilding a TT system rather than worrying about this 'exporting PME' stuff.

The minimum CSA will be 10mm from table 54.8

 

[jamesb1]

hi thanks again for the replysi have some 4 core 10mm swa that i was going to use would i still need to run a seperate 10mm earth into there aswell ? or can i use a spare core ? i also have already bought the metal clad db is this ok to use still with a imported pme system ? and the garage/unit has a water supply via a plastic supply from the house mdpe ? blue pipe then 1 meter of copper with a tap on the end

 

[pushrod]

Are you Part P ? - you do realise this work is notifiable and has to be fully tested, the results and inspections of which need to be recorded on BS7671 forms or equivalent.

 

[SimpleSimon]

hi thanks again for the replysi have some 4 core 10mm swa that i was going to use would i still need to run a seperate 10mm earth into there aswell ? or can i use a spare core ? i also have already bought the metal clad db is this ok to use still with a imported pme system ? and the garage/unit has a water supply via a plastic supply from the house mdpe ? blue pipe then 1 meter of copper with a tap on the end

I don't think it's best to use a metal clad db. If you get any earthing problems or future upgrades of the structure, you may find you'll have to TT the structure and therefore it would be against regs to use a metal one.
Shouldn't need to bond the water with plastic incoming. But this is notifiable work.

 

[jamesb1]

Hi yes guys thanks I know it notifable work i have my nvq3 and 17th edition I work for a jib firm but it's all industrail stuff im going to get my part p
berfore this job is done but just want to know what the yes and nos are

 

[pushrod]

I don't think it's best to use a metal clad db. If you get any earthing problems or future upgrades of the structure, you may find you'll have to TT the structure and therefore it would be against regs to use a metal one.
Shouldn't need to bond the water with plastic incoming. But this is notifiable work.

What reg are you thinking of there or are you just talking about the possibility of the 'new' TT being connected to the original CU and the need to de-link them?