BS7671 Green Book

dichroic · May 13, 2012

Can someone tell me where in the new green book it gives the maximum disconnection time for a circuit on a TN system when there is likelyhood of contact from livestock? I just can't find it ?

Dichroic

telectrix · May 13, 2012

don't think there is a specific time in the regs. however, 705.411.41... RCDs, so the disconnection times applicable to the RCD/s will apply.

Richard Burns · May 13, 2012

Agricultural with contact with livestock not allowed a TN system, must be TT.
Section 7 something.

Edit: Sorry Tel's right

telectrix · May 13, 2012

Richard Burns said:
Agricultural with contact with livestock not allowed a TN system, must be TT.
Section 7 something.

or TN-S

dichroic · May 13, 2012

Thanks guys............to clarify;

Protection against shock may be provided by

1: ADS with additional protection by rcd (30ma) for final circuits supplying socket outlets rated at 32A or less.
2: ADS with additional protection by rcd (100ma) for final circuits supplying socket outlets rated at more than 32A.
3: ADS with additional protection by rcd (300ma) for all other circuits.

OR

by the use of SELV or PELV.

Where does it state that TN-S systems cannot be employed?

Regards

Dichroic

Sparky Ninja · May 13, 2012

It doesn't, only a TN-C system is prohibited.

In locations intended for livestock, supplementary bonding shall be required.

spark 68 · May 13, 2012

Where does it state that TN-S systems cannot be employed?

See Tels post ^^^, it doesn't, it says TNC-S/PME is not recommended where there is no metal grid laid in the floor Sec 705.

And for ADS the 0.2s has been removed, replaced by the requirement of RCD's