Bonding

[biscuitman]

Hello Everybody,

Just wondered if anyone can help, I had a fixed wire testing done on our factory, it is just asmall unit around 600sqm. one of the code 1's was that the bonding to water and gas needed upgrading.

When I had another electrician come and quote I told him that the bonding failed as it needed up grading to 25mm, he told me that it is currently 10mm and without doing caluclations cant see in the world why it needs to be 25mm. it is around 30 metres in length.

Now I dont know what to do or who is right, is my test certificate right? it also contained a code 2 for disconnection of a socket we no longer use and the 2nd electrician seemed a bit concerned.

Thank you

 

[ricicle]

Could well need upgrading depending on the type and size of supply.

 

[ericmark]

I have too many times followed an electrical condition report to find both items missed and items included which if one is to follow the Electrical Safety Councils guide lines should not have been included.

I have questioned some of the Electrical Safety Councils guide lines. And this is the point it is a personal assessment by the guy doing the test and although some items are cut and dried as to coding many are not so easy to criticize either for inclusion or omission from the report.

I have quoted the 17th Edition many times to support my point as it if an item should pass or fail but the 17th does not categorise as to if a failure is 1, 2, 3, or 4 on old or 1, 2, or 3 with new system. The 17th (BS7671) only says if it passes or fails.

As to earth cables there is a TABLE 54.1 and Table 54.7 with the main being TABLE 54.8 all which try and say what size earth is required. The earthing system TT or TN and the supply cables sizes all have a bearing on the size required. It would be a brave man to give an answer without visiting the site.

 

[biscuitman]

Thank you for your replies,

I thought that when a test is done it is done to a regulation that all electricians follow, not that it is their own choices as such, does that mean that some electricians could end up costing companies more should they fail extra parst than that of another electrician that may think the same parts are fine and passable?

Thanks

 

[EFLImpudence]

Depends which one is correct.

 

[biscuitman]

and how would someone in my position know?

 

[RF Lighting]

By asking on DIYnot.com and providing us with all the information we require.

 

[Spark123]

An EICR should be carried out to the current edition of the regs, it depends which electrician understands the regs better!
The recommended maximum resistance of a Main Protective Bonding conductor is 0.05Ω for a bog standard TN 100A service. At 20°C a 10mm² conductor has a resistance of 1.83mΩ/metre. This equates to somewhere in the region of 27m so in theory at least the first sparky sounds rightish! 16mm² would probably be OK at 30m, that is of course if you have a 100A TN service. In the case of TN-CS the DNO can require you to have bigger.

 

[RF Lighting]

Also there is regulation 544.1.1 which may requires a larger MPB conductor if the supply is PME and the incomming neutral CSA is over 35.0mm²

 

[ricicle]

Also there is regulation 544.1.1 which may requires a larger MPB conductor if the supply is PME and the incomming neutral CSA is over 35.0mm²

Which is what I was hinting at

 

[biscuitman]

thank you again for your replies, the second electrician did mention 16mm after looking around, these tests do seem like a bit of an open book to me.

I can post all day long but again it would be your opinion's against someone else's.

Should I stick to NIC only electricians? would this guarentee some sort of standard?

Should I stick to test only companies? I get plenty of calls from these weekly, infact they never stop pestering for fixed wire and pat testing work

 

[Scoby_Beasley]

Should I stick to NIC only electricians?

Not necessarily as it may only mean they have a bigger wallet to join a scheme!!