BS 8436 Cable

HI Alan


As I state at the end of my last post full cable sizing calculations will be undertaken to confirm compliance with the requirements of BS 7671:2018.

BS 8436 explicitly states that "protective devices used for the cables covered by this British Standard shall be either a Type B circuit breaker conforming to BS EN 60898 or a Type B RCBO conforming to BS EN 61009-1."  Not exactly any wiggle room there - using a Type C breaker would put the cable outwith its product standard.


The standard also states that the cables are "intended for installation in air (which includes installation in trunking or other closed systems), and in thin partitions and building voids when connected to a suitably selected protective device...When cables are to be installed in any other environment, reference should be made to the cable manufacturer."  Again, pretty clear - If the manufacturer has data for installation on a tray, fine.


P

What I was digging for was to find out what the cables supply and were do they go when they come off the tray.


if they come off the tray and run through a building void you’re back to square one. 


Andy Betteridge.

It doesn't really matter what they serve does it?


The key constraints are the required circuit breaker type/rating, the limitation on available conductor sizes and the installation method information available from the manufacturer.


P

PWW235 - Exactly.?

Hi Weirdbeard.


To be perfectly honest no I haven't contemplated the use of HiTUFF. 


I was trying to get away from the black industrial look. I am looking to use the BS 8436 Cable in Commercial installations.


I have recently spoken to Prysmian Technical Department who were very helpful. They referenced the BS 8436 Document where it stated that only Type B MCB's to BS 60898  can be used with the cable.


So I am resigned to design around B Type breakers for lighting and small power circuits which may not be a huge problem and look for alternative cables for supplies for items such as gas interlock panels etc.


Thanks for your input.

pww235:

It doesn't really matter what they serve does it?


The key constraints are the required circuit breaker type/rating, the limitation on available conductor sizes and the installation method information available from the manufacturer.


P

Of course it matters what they serve, presumably the connected equipment HAS TO BE protected by a a Type C MCB  because it has an inrush current that would trip a Type B MCB.


Or are you applying some unwritten rule that in commercial installations Type C MCBs are used, because that’s the way it’s done?


Also if the cable is in a safe place within the cable tray why does it need any armour or earthed protection at all, unless it needs it when it drops out of the tray to the connected equipment?


I presume this is going to be some cable choice based on the colour of the sheath available rather than what the cable is actually designed for, in which case you drop the spec done to some white sheathed low smoke twin and earth cable, the customer won’t know the difference when they are stood looking up at it.


Andy B

Unless of course the foil is preferred for EMC reasons....


 - Andy.

As I have previously stated a number of times, I was simply looking for an alternative to SWA and getting away from an industrial look..


No big deal. Prysmian have confirmed that BS 8436  identifies B Type breakers only.


I will will roll with this. Some of the loads are 3 phase some single some loads require C type whilst others will be fine with B Type.


I would like to thank everybody who has contributed to this post. It has been both interesting and enlightening to read each and every reply. It has indeed been a very positive and rewarding experience.