PME supply at my new house.

[wcavanagh]

Been reading up about PME, my new house has no connect to MET or Gas. Found te following, is this correct.

With PME. the neutral and earth conductors of the supply are combined. The supply company connects the neutral solidly to earth frequently throughout the distribution network. At the customer's connection point the company supplies an 'earth' (which is actually connected to the neutral) to which all the installation earths and equi-potential bonding are connected. Note that within the installation, the earth and equi-potential bonding are kept separate from the neutral in the usual way.

With PME. there is a potential danger in that if the combined neutral/earth conductor of the supply became broken (very unlikely but nevertheless possible), the voltage on the earth conductors could rise towards the full supply voltage. It is most important therefore that equi-potential bonding is rigorously applied in installations supplied by PME. The minimum size of main bonding conductor is 10 sq mm but may need to be up to 25 sq mm depending on the size of the incoming neutral/earth conductor: the supply company will advise you.

 

[westie101]

Correct,

 

[wcavanagh]

Fantastic, as soon as I move in I will make sure it is sorted right away.

Do I phone the DNO or the people I will pay the bill for?

Sorry if it's silly, it's my 1st house so making sure everything is sorted.

Also who will check the size of earth cable from the cut out, it is no more than 6mm at the moment.

Thanks again
Will

 

[westie101]

A
At the end of the day there is nothing to say that the earthing is PME, there are a number of other earthing types and you may need an electrician.
Yes you should phone the DNO as it it their responsibility. (if for no other reason than they may be able to tell you the earthing type)

 

[riveralt]

With PME........The minimum size of main bonding conductor is 10 sq mm but may need to be up to 25 sq mm depending on the size of the incoming neutral/earth conductor: the supply company will advise you.

But in that case your line or neutral conductor would be 70mm - bit big for a domestic property.

Looking at your photographs uploaded 6 days ago, it looks as if your incoming tails are either 16/25mm so your earthing conductor should be 16mm - difficult from the photograph but it looks like a 10mm.

 

[wcavanagh]

A
At the end of the day there is nothing to say that the earthing is PME, there are a number of other earthing types and you may need an electrician.
Yes you should phone the DNO as it it their responsibility. (if for no other reason than they may be able to tell you the earthing type)

Thank you, the cut out has a label on it saying PME. Here is a picture.

Untitled

• wcavanagh
• 8 Jun 2011
• 2

Thank you again for taking time to reply,

Cheers,
Will

 

[wcavanagh]

With PME........The minimum size of main bonding conductor is 10 sq mm but may need to be up to 25 sq mm depending on the size of the incoming neutral/earth conductor: the supply company will advise you.

But in that case your line or neutral conductor would be 70mm - bit big for a domestic property.

Looking at your photographs uploaded 6 days ago, it looks as if your incoming tails are either 16/25mm so your earthing conductor should be 16mm - difficult from the photograph but it looks like a 10mm.

Thanks, 100% its not 10mm, I took some 10mm earch cable with me, and it was almost twice as thick as the cable from the cut out.

I will have the keys in 2 weeks, so guess 1st job has to be to get a sparks in.

Cheers,
Will

 

[westie101]

Looking at your photographs uploaded 6 days ago, it looks as if your incoming tails are either 16/25mm so your earthing conductor should be 16mm

A point of confusion, according to our regs for a supply neutral conductor size up to 25mm2, 10mm2 earthwire is acceptable to us.

The service cable looks to be 25mm2 copper.

 

[Taylortwocities]

When you say "new" house.

Is it really new or is it new to you?

 

[wcavanagh]

When you say "new" house.

Is it really new or is it new to you?

Yes new to me moving, house was built 1930

 

[riveralt]

Looking at your photographs uploaded 6 days ago, it looks as if your incoming tails are either 16/25mm so your earthing conductor should be 16mm

A point of confusion, according to our regs for a supply neutral conductor size up to 25mm2, 10mm2 earthwire is acceptable to us.

The service cable looks to be 25mm2 copper.

I picked this up from the OSG and Table 54.7 of the BRB - where the cross sectional area of the line conductor (S) (16<S<=35) the protective conductor of the same material as the line conductor shall be 16mm.

 

[wcavanagh]

I will be having a plumber in to install central heating as soon as I move, while he has the floor up, it would be a good time to add the earth cable from the mains water entry area back to the cut out area.

I doubt the sparks will be there while this is being done, would it be worth my while laying in this cable? Ready for connection when I get all this sorted? Just thinking save taking up floor boards twice.

If so, should this be 16mm then not 10mm? As there is nothing in at the moment, would like to make sure the correct size is in place?

Or is this a job for the sparks?

 

[JohnW2]

[I picked this up from the OSG and Table 54.7 of the BRB - where the cross sectional area of the line conductor (S) (16<S<=35) the protective conductor of the same material as the line conductor shall be 16mm.

Yes, but the pre-amble to Table 54.7 (i.e 543.1.4) indicates that Table 54.7 is only for use when one can't be bothered to calculate the required CSA properly (per the preceding sections of 543.1) - the implication, I think, being that Table 54.7 gives over-cautious figures for the lazy, but that calculation will often show a smaller CSA to be adequate.

Kind Regards, John.

 

[ban-all-sheds]

Or is this a job for the sparks?

Get some clamps and DIY.