Consumer Unit located Remotlly from Supply Cut OUT

[Deleted member 14631]

Some thing I have not really come accross before but I have a Client looking at a renovation of an old Property. For various reasons including Western Power the Clients PME supply may be located in a Garage. However the House will be about 20 metres away from the Garage and the main consumer unit will be located in the house. I am assuming I would connect the Consumer unit as a TT to the garage with an earth rod located at the consumer unit at the house. There are loads of of awkward little things at this job and I dont know why the supply and consumer nit are worrying me

 

[ezzzekiel]

run a swa from service head to house, a sfu will be required in the first 3metres of the swa

 

[Deleted member 14631]

run a swa from service head to house, a sfu will be required in the first 3metres of the swa

Sorry what is an "sfu" you refer to in the first 3metres

 

[malcolmsanford]

SFU = Switch Fuse Unit something like that

Can I ask why your thinking of ditching the PME in the garage for a TT system

 

[Deleted member 14631]

Sorry realise what SFU is now. Was going to have a supply isolator installed by Western Power and then have the main supply fuse protect the cable to the consumer unit as per normal tails.

Was going to treat the main house consumer panel as a remote building. Have not done the calculations on cables and Volt Drop, earth resistance yet ( early days)

 

[malcolmsanford]

Sorry realise what SFU is now. Was going to have a supply isolator installed by Western Power and then have the main supply fuse protect the cable to the consumer unit as per normal tails.

The isolator is not a protection device so the DNO will most likely insist the those 20mts of tails be protected withing 3 meters of their head by a swich fuse.

Was going to treat the main house consumer panel as a remote building. Have not done the calculations on cables and Volt Drop, earth resistance yet ( early days)

All your really doing is extending a set of tails from the meter. I would not class this as an export of the earth and keep it PME. Where do the services for water and gas come in, at the garage also ?

 

[Deleted member 14631]

Thank you malcolmsansford.

The water comes into the main house on Plastic, very Rural location and NO gas. am assuming house inside will be in Copper from Stop cock at the min

Your comment on exporting and keeping it PME actually takes me back to my initial thoughts before some else ( outside forum) mentioned TT etc I will re-evaluate and gut instinct ( before the maths) will take me back to very long tails and earth cable from Garage to main consumer unit

 

[malcolmsanford]

Thank you malcolmsansford.

The water comes into the main house on Plastic, very Rural location and NO gas. am assuming house inside will be in Copper from Stop cock at the min

Your comment on exporting and keeping it PME actually takes me back to my initial thoughts before some else ( outside forum) mentioned TT etc I will re-evaluate and gut instinct ( before the maths) will take me back to very long tails and earth cable from Garage to main consumer unit

You can test if the house pipework is copper that it is an extraneous conductive part by doing an IR test with a wander lead from your MET to each pipe and if it exceeds 22kohm then there is no need to bond it.

 

[Deleted member 14631]

Thanks I was not clear on the Pipe work. The property is undergoing a full renovation hence the Mains having new Locations because of poles in the road etc and relocating incoming to Garage unit.

Hence there is No Water at Present except the inevitable MDPE blue Pipe in a hole in the ground as the house has been gutted. I did not know if they were plumbing in Plastic or old fashion Copper and Have not seen underground if the Blue MDPE is been replaced from the main to the house yet.

MAy I ask one question . When People take about exporting earth or not eg to a garden shed. What drives using an exported Earth or a Local Earth at Shed. Or is it just a mater of doing the Calaculations and Earth measurements.

 

[gamblor6]

the fabric of the remote building and the dno are the 2 main factors there.

 

[Engineer54]

Nothing to do with the fabric of the installation or the DNO!! The main consideration and limiting factors are when there is extraneous conductive parts, ie Water pipe etc, and distance, where it then becomes uneconomical running a suitably sized bonding conductor!!!


EDIT..... When we are talking about PME supplies that is...

 

[High Tower]

cut out to Switch fuse with no more than 3m of tails, 25mm SWA 3 core, glanded with CW glands to switch fuse, armouring earthed for the purposes of Fault protection, black core slieved for the purpose of a earth conductor, glanded to the main CCU.

 

[Deleted member 14631]

cut out to Switch fuse with no more than 3m of tails, 25mm SWA 3 core, glanded with CW glands to switch fuse, armouring earthed for the purposes of Fault protection, black core slieved for the purpose of a earth conductor, glanded to the main CCU.

Thanks for this

 

[gamblor6]

Nothing to do with the fabric of the installation or the DNO!! The main consideration and limiting factors are when there is extraneous conductive parts, ie Water pipe etc, and distance, where it then becomes uneconomical running a suitably sized bonding conductor!!!


EDIT..... When we are talking about PME supplies that is...

extraneous conductive parts like the structural steel? and the fact some dno,s wont let you?
agreed about the too expensive to run a bond tho.

 

[Noton1205]

From cut out to meter, from meter to switch fuse, then run swa from switch fuse to consumer unit. Thats the way i would do it to keepthe pme.

 

[Colin Integrale]

cut out to Switch fuse with no more than 3m of tails, 25mm SWA 3 core, glanded with CW glands to switch fuse, armouring earthed for the purposes of Fault protection, black core slieved for the purpose of a earth conductor, glanded to the main CCU.

Yep. Did the same today as it goes.

 

[Engineer54]

extraneous conductive parts like the structural steel? and the fact some dno,s wont let you?
agreed about the too expensive to run a bond tho.

I can't say for all DNO's but i have a good friend in one DNO company who is an area manager coming up to retirement. According to him, apart from petrol stations Caravans sites and a few other unrelated areas they are not really interested. As it happens, he bought some land some years ago and built what is a steel framed brick and block infill house. And yep, he's on a PME supply, cad-welded bonding to MET.

Problem with PME supplies, for the average electrician, is there are just too many myths flying around out there, that confusion seems to rule!!!

 

[gamblor6]

I can't say for all DNO's but i have a good friend in one DNO company who is an area manager coming up to retirement. According to him, apart from petrol stations Caravans sites and a few other unrelated areas they are not really interested. As it happens, he bought some land some years ago and built what is a steel framed brick and block infill house. And yep, he's on a PME supply, cad-welded bonding to MET.

Problem with PME supplies, for the average electrician, is there are just too many myths flying around out there, that confusion seems to rule!!!

ok that ill agree to.

 

[TPES]

Having a debate with another spark.

Same situation is that the customer wants there CU fitting in the garage and moving from under the stairs, prob 15m from the intake.. I suggested running SWA from switch fuse under stairs to new CU position, my mate can't see why I can't run 25mm tail set to new CU, I said if you did you would need to RCD the tails, and he said yeah stick 100ma on it..

 

[malcolmsanford]

Why is it a TT system..................... If your not going to bury the tails in the wall then you don't need to fit an RCD at all.

 

[acquiesce1979]

Hello, i know this is old now but for others looking you would need to have a distributors switch after the main meter (where you read the meter) then you would have to have a 80ma fuse then meter tails to your new consumer unit.... location! you would only need to convert to TT system if the board in the garage was seperate to main consumer unit... Although if you dont have the ability to find the information in the regs then maybe you should think of consulting a qualified person! because Building Control would have to notified and they will not like it!!!

 

[Knobhead]

Now that what I call energy efficient. You can rewire my place if you can get it to work on an 80ma fuse!

 

[topquark]

Now that what I call energy efficient. You can rewire my place if you can get it to work on an 80ma fuse!

I knew LED technology would go far

 

[Engineer54]

Hello, i know this is old now but for others looking you would need to have a distributors switch after the main meter (where you read the meter) then you would have to have a 80ma fuse then meter tails to your new consumer unit.... location! you would only need to convert to TT system if the board in the garage was seperate to main consumer unit... Although if you dont have the ability to find the information in the regs then maybe you should think of consulting a qualified person! because Building Control would have to notified and they will not like it!!!

Here we go again TT this, TT that, ....when are these people going to take the time and learn about the industry they are in??

 

[robsparky1975]

Here we go again TT this, TT that, ....when are these people going to take the time and learn about the industry they are in??

Perhaps in another 6 weeks time lol

 

[Knobhead]

I don’t think he’s quite got where the service head is or the CU. Typical 6 week wonder, (2 weeks in to his course)!

Still want to know how to run a supply off an 80ma fuse though. There’s a fortune to be made there!

 

[acquiesce1979]

Are you referring to me? and not that I have to explain myself but I have been a director of an electrical contracting firm which over the last 5 years has turned over 2mil a year. So thank you for your insight but I dont need it.

 

[Engineer54]

Are you referring to me? and not that I have to explain myself but I have been a director of an electrical contracting firm which over the last 5 years has turned over 2mil a year. So thank you for your insight but I dont need it.

And just how many, unnecessary TT systems have you installed in those 5 years??

 

[Guest123]

which over the last 5 years has turned over 2mil a year.

Turnover is vanity
Profit is sanity
Cashflow is reality

:sifone: