adiabatic test of mian bond

[beaver74]

Hi all have tested a flat were the main bond is only 6mm
the incomer is 1361 60A
main earthing conductor is 16.oomm

doing the adiabatic calculation what disconnection time would i use to assess if this conductor is man enough (and yes i know it should be 10.00 but the customer want have any work done so i want to report to him and sleep at night.

on the same theme what disconnection time would you use generally 0.4 0.1

 

[Sintra]

Have a read of reg 543.1.3 which states that the time is the operating time of the disconnecting device corresponding to the fault current.

Then check table in appendix 3.

 

[dichroic]

What earthing system is it? TT TN-C-S OR TN-S ?

Regards

Dichroic

 

[Guest123]

You cant use the adiabatic to size bonding conductors........It depends on the earthing system present and condition of the conductor itself as to wether 6mm is still sufficient tor not.

 

[dichroic]

Where PME conditions do not apply, Regulation 544.1.1 requires a main bonding conductor to have a csa not less than half the csa for the earthing conductor of the installation and not less than 6 mm2.

Where PME conditions apply, Regulation 544.1.1 requires the main bonding conductors to be selected in accordance with the neutral conductor of the supply and Table 54.8H.

Regards

Dichroic

 

[Sintra]

I missed the bit about main bond and presumed the op was talking about the Main earthing Conductor.

 

[beaver74]

What earthing system is it? TT TN-C-S OR TN-S ?

Regards

Dichroic

sorry p.m.e system

 

[dichroic]

Just to be clear, you are on a pme system or otherwise known as a TN-C-S system. When using table 54.8 in the regs it is referring to the size of the neutral conductor inside the armoured cable of the supply cable NOT the size of the neutral conductor of the 25mm tails on the consumers side:


It is important to appreciate that the ‘supply neutral conductor’ referred to in Table 54.8 of the regulations is the neutral conductor of the electricity distributor’s low voltage network (otherwise known as the combined protective and neutral (PEN) conductor). It is not the neutral conductor on the consumer’s side of the supply terminals, which may have a smaller csa.

Many people think that this table is referring to the size of the "tails" neutral conductor.

Regards

Dichroic.

 

[sparkylad]

If the MPB is not being upgraded it is essential to check out the connection at the Clamp to ensure circulating currents have not caused overheating..then make comment on it on the P.I.R as code 4.