Dear All
Im quoting on changing a fuse board and the earth bonding to the gas is 6mm. TNCS system 100A main fuse at cutout (sealed so not confirmed)
The flat has concrete ceilings and floors and the bonding cable is deep in the structure of the building. No obvious route to run in a 10mm. I rang the NICEIC for a bit of advice, they said
" Why are you looking to replace the cable"
I said I thought all bonding had to be 10mm
He said that his guess is the flat was wired under 15th edition regs and at the time 6mm was acceptable.If a bonding cable is in place and shows no signs of heat damage it was perfectly acceptable to leave it in with a note on the cert.
Still not convinced I spoke to another spark I know and, confused he rang the NICEIC, same question different answer.
" No it needs replacing with a 10mm no matter what"
How can I get 2 different answers from them and which is right ?
^^^ Wot Tel said^^^ ...Make sure your EIC states that the bonding was inspected,tested and showed no sign of thermal damage at the time of your install,rear end covered then.
I've had this problem a few years ago. I asked the same question
They if it was intact and you carry out an r2 and check your cutout fuse.i did loads of jobs like that.
You have most deffo proved continuity with 0.05 ohms,
But better than that you have an acceptable reading when tapping away numbers on your calculator.
Luckily for you the seals are missing on the cut out fuse carrier (Henley block)
So what size is the primary device 60, 80, 100, BS 1361, BS88,
Whats the let through current with relation to possibly 6k circuit device 16k primary.
Whats the PFC in relation to the Ze
In other words can the cpc handle possible fault overload currents generated before the circuit is disconnected by the protective device.
If you want to be totally confident and prove or justify your findings
then adiabatic S= √(I²×t)/k And a little research is the way to go.
Because they are about as much use as an ash tray on a motorbike when it comes to any real electrical work. I bet you could visit NIC headquarters and count on only one hand the number of guys/gals up there who actually know what they're talking about.
I must admit, I was a bit confused when reading the OP, primarily because I've never heard of 'earth bonding'. I guess this could be the cause of confusion??
This always makes me laugh “shows no sign of physical or thermal damage”.
The conductor won’t show any sign of thermal damage unless it’s been a part of clearing a heavy fault. Normally it just sits there doing nothing other than look unsightly.
Just in case you'd like to see it in black and white.. Best Practise Guide No6 (Issue 2) - 'Consumer Unit replacement in domestic and similar premises' says the following on Page 5, Section 6.1(note 3)
"A 6mm main protective bonding conductor size could be deemed adequate where the minimum size required by regulation 544.1.1 of BS7671 is 10mm if the bonding conductors have been in place for a significant time and show no signs of thermal damage."
This always makes me laugh “shows no sign of physical or thermal damage”.
The conductor won’t show any sign of thermal damage unless it’s been a part of clearing a heavy fault. Normally it just sits there doing nothing other than look unsightly.
Well not really,if the service is at earth potential then in theory a sizable chunk of the normal neutral current could divert down the bonding wire on a TNCS system.
Reply to NICEIC conflicting advice in the Certification NICEIC, NAPIT, Stroma, BECSA Forum area at ElectriciansForums.net
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