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.
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...
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
Just out of (genuine) interest Westy can you give me the reg number for the 16th where SB was not allowed to reduce a Zs ?, I still have regs books and some OSGs going back to the 15th ed and I will look it up.
The special locations bit in my previous post, which I never bothered writing out is...
In the 17th GN8 amd3 (which is the last GN series I currently have) it gives reg 411.3.2.6 and states "Supplementary bonding is required by BS7671 to be provided in the following circumstances: where, in the event of an Earth fault, the conditions for automatic disconnection cannot be fulfilled...
Exactly Des,
If the spark had charged on the low side it would have been pay peanuts yada yada, if he had charged high then it would have been rip-off merchant, I don't see how the electrical firm could have won a fair trial on here :(
the plasterer looked crap but I digress, Essex knows F-all...
It may cause some confusion in domestic as it is not in the OSG ;) nor in app15 pics in the regs book ;), and wasn't really seen that much in that environment until fairly recently (more frequent kitchen re-fits ?) , however in the industrial/commercial world it has been around for almost ever...
Just for further information regarding Testing/certifying 'lollipop' circuits here is Voltimums take on it.
Common issues relating to hybrid ring/radial final circuits - https://www.voltimum.co.uk/articles/common-issues-relating-hybrid
In domestic it tends to be done when only the kitchen is refurbed, usually repurposing the 6mm^ feed that was formerly used for the electric cooker circuit , save ripping the rest of the house apart.
In Industrial/commercial it may be done for volt drop/max Zs reasons using a larger feeder...
Interesting and fascinating discussion about CE marking and EN standards as ever chaps :) however the OPs location is given as South Africa, I don't think any of these directives apply to him :cool:, no doubt similar national/international equivalent standards do though. :rolleyes:
At least they didn't do what one spark did to a friend of mine :mad:namely told the customer they had a "faulty Earth" :mad::eek: and promptly disconnected it (CPCs) from a S/O :mad:, I got involved later when instead of the RCD (split load board) tripping the fault resulted in the MCB tripping...
These Official Forum Sponsors May Provide Discounts to Regular Forum Members - If you would like to sponsor us then CLICK HERE and post a thread with who you are, and we'll send you some stats etc