Upgrading CU

[ml1936]

Is it still ok to upgrade CU is main bond is only 10mm and customer not willing to pay to upgrade to 16mm because of mess it'd cause?

 

[RF Lighting]

How big is the incomming supply?

If you are talking ablout a standard domestic supply, then 10.0mm² is all that is required for the protective equipotential bonding.

If you mean the main earth from the supplier, then this would need to be replaced with 16.0mm²

 

[Spark123]

If they are not willing to pay for you to make the system compliant with the regs, walk away.

 

[GaryMo]

Are you talking about the main earthing conductor or protective equipotential bonding conductors?

Earthing arrangements (TN-S, TN-C-S, TT)?
Size and type of main fuse?
Ze / PFC?

 

[ml1936]

TN-C-S
0.34ohms Ze
1.3kA PFFC
60A Main Fuse

Main Bonding

 

[GaryMo]

TN-C-S
0.34ohms Ze
1.3kA PFFC
60A Main Fuse

Main Bonding

As you say it's the 'Main Bonding' (Protective Equipotential Bonding Conductor(s)) you're talking about then there isn't a problem as it's already 10mm.
There's no requirement to upgrade it to 16mm unless the supply neutral is between 35mm and 50mm (not likely).

What size is the Main Earthing Conductor?

 

[lazygit]

As already said 10mm is fine for main bond (up to 25M in length)
16mm for earth conductor is preferred but smaller is not necessarily non compliant.
Use the Adiabatic equation

 

[Spark123]

How do you use the adaibatic?
Generally, with TN-CS you need to contact the distribution network operator and ask them what size is required.

 

[lazygit]

How do you use the adaibatic?
Generally, with TN-CS you need to contact the distribution network operator and ask them what size is required.

543.1.1 basically says you can do 1 of 2 things.
1- Either select the earth from table 54.7 which means 16mm earth for line conductors up to 16mm.
2- Use the equation from 543.1.3 to caculate the earth size based on fault current and the time it takes the protective device to operate.

If the network operator has other demands regarding earth size then they should take priority, but all Im saying is what the regs book requires you to do.

In my opinion the bigger the better when it comes to the size of the incoming earth, because if the meter is under the stairs there is possibility of being pulled off completely when the ironing board gets put back

 

[RF Lighting]

543.1.1 basically says you can do 1 of 2 things.

What does the very first line of 543.1.1 actually say, without paraphrasing?

Pay particular attention to the six words between the first two commas.

In my opinion the bigger the better when it comes to the size of the incoming earth, because if the meter is under the stairs there is possibility of being pulled off completely when the ironing board gets put back

I don't think I've ever seen a meter pulled off a wall, and even if it had been, what difference would the size of the main earth make? And besides which, this thread is about the size of the Protective Equipotential Bonds, not the main earthing conductor.

 

[lazygit]

What does the very first line of 543.1.1 actually say, without paraphrasing?

Pay particular attention to the six words between the first two commas.

I apologies for creating confusion, and as you have pointed out 543.1.1 refers to earthing and not bonding.
The OP did not make it clear if we were talking about earthing or bonding. I decided to comment on both & point out that earth conductors less than 16mm are not always non compliant to the regs.

I don't think I've ever seen a meter pulled off a wall

Neither have I.
After reading my reply again it does look like I am talking about pulling the meter off the wall, but I actually meant pulling an earth conductor of small CSA from the MET.
Sorry for taking this thread off at a tangent, and not giving a clear reply in the first place

Regards

edited to correct some bad grammer (although its still pretty lame)