Discuss How to test a circuits in steel conduit as the cpc in the UK Electrical Forum area at ElectriciansForums.net

So Ian, are you saying in effect that SB can be used to lower a Zs to achieve disconnection times ?, I do have the 18th regs book but I am just being lazy ;)

I don't have the 18th GNs yet, but I am considering getting them
 
Section 419 deals with achieving fault protection through the likes of supplementry bonding if ADS can’t be achieved by 411.3.2
Is this with intent of reducing Zs or a measure to reduce danger to exposed parts.
 
So Ian, are you saying in effect that SB can be used to lower a Zs to achieve disconnection times ?, I do have the 18th regs book but I am just being lazy ;)
Supplementary bonding to the location between accessible exposed conductive parts and extraneous parts and circuits is one method.
Another more commonly used method is Rcd protection
 
There are basically two reasons for SB, the special locations part is to do with reducing Ut to keep it below 50V, medical locations below 25V, back in the 16th agricultural locations required Ut below 25V as well I recall, but I don't recall now which specific amd, or if it ever changed in that entire edition.
The other part is to achieve disconnection times and was to reduce Zs by default, the regs are worded --- backward in a lot of cases.
 
There are basically two reasons for SB, the special locations part is to do with reducing Ut to keep it below 50V, medical locations below 25V, back in the 16th agricultural locations required Ut below 25V as well I recall, but I don't recall now which specific amd, or if it ever changed in that entire edition.
The other part is to achieve disconnection times and was to reduce Zs by default, the regs are worded --- backward in a lot of cases.
I can’t even remember the 16th that well
Wish I had kept my yellow copy I used to pass the exam.
What I do remember from that time is the awful bonding and in particular the radiator clamps we used to supplementary bond the bathrooms
Looked hideous if you couldn’t hide them
 
I could dig them out Westy, but what do you make of the second part of reducing disconnection times ? this part has nothing to do with Ut or special locations.
 
No, I could get my 16th editions out, but as the disconnection times part are still in the current edition and GN8 for the 17th amd 3 there is not much point really, I will look up the regs spin posted up later, and see what actually changed.
 
This is the latest version:
419.3 Except where Regulation 419.2 applies, if automatic disconnection cannot be achieved in the time required by Regulation 411.3.2.2, 411.3.2.3 or 411.3.2.4 as appropriate, supplementary protective equipotential bonding shall be provided in accordance with Regulation 415.2 and the voltage between simultaneously accessible exposed-conductive-parts and/or extraneous-conductive-parts shall not exceed 50 V AC or 120 V DC.
 
In the brown book 16th 413-02-15 is deleted in 1992 amd2

This reg is present in the green book amd1: 1992 16th though, and says pretty much the same as the blue book above (which I also have).

The 16th was a bit strange as there was at least one reset in between the green book amd 1 :1992, the blue book :2001 (no amd given even though it is almost a decade later) and the brown book :2004 both amd 1+2

brown book 16th.jpg

green book 16th.jpg
 

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