My assessor said that the minimum CSA for a Main earthing conductor for a TT was 16mm. I questioned this as I thought it was 4mm.
Regulation 542.3.1 states every earthing conductor shall comply with section 543.
Section 543 refers mainly to the adiabatic (reg 543.1.3) or reg 543.1.4 (table 54.7), so if the CPC meets the adiabatic then its ok.
The on site guide even has a Table ( 4.4(ii) ) on page 41 (green copy) showing that 4mm is acceptable for a TT. I'm assuming this is from 543.1.1.
The assessors justification for the 16mm on a TT was that there is a diagram in OSG showing the CPC on a TT with 16mm written next to it (see page 16, fig 2.1(iii) - green OSG). Also the Electricians guide to the building regs - reprinted 2012 version (Table 3.3.2b - page 40) clearly shows that a 16mm CPC is required for a TT (assuming 25mm tails)??
How do you guys read the regs with regards minimum size CPC for a TT?
Also, just as an aside, why do we always have to have 16mm CPC for PME or TNS? If the regs say we can use EITHER reg 543.1.3 OR 543.1.4 why cant we just use the adiabatic (reg 543.1.3) and perhaps use a 6mm if it meets the reg?
Regulation 542.3.1 states every earthing conductor shall comply with section 543.
Section 543 refers mainly to the adiabatic (reg 543.1.3) or reg 543.1.4 (table 54.7), so if the CPC meets the adiabatic then its ok.
The on site guide even has a Table ( 4.4(ii) ) on page 41 (green copy) showing that 4mm is acceptable for a TT. I'm assuming this is from 543.1.1.
The assessors justification for the 16mm on a TT was that there is a diagram in OSG showing the CPC on a TT with 16mm written next to it (see page 16, fig 2.1(iii) - green OSG). Also the Electricians guide to the building regs - reprinted 2012 version (Table 3.3.2b - page 40) clearly shows that a 16mm CPC is required for a TT (assuming 25mm tails)??
How do you guys read the regs with regards minimum size CPC for a TT?
Also, just as an aside, why do we always have to have 16mm CPC for PME or TNS? If the regs say we can use EITHER reg 543.1.3 OR 543.1.4 why cant we just use the adiabatic (reg 543.1.3) and perhaps use a 6mm if it meets the reg?
