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521.10.202

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521.10.202

Posted by whjohnson on Oct 8, 2019 10:39 pm

Plastic cable clips!
Are they completely banned now? What about vertical switch and socket drops which will be plasterboarded over? Would this situation be exempt?

Re: 521.10.202

Posted by Chris Pearson on Oct 8, 2019 10:56 pm

No and yes.

This topic came up during my annual assessment last week. We were agreed that cables clipped direct at waist height (e.g. in a workshop) are unlikely to present a hazard in the event of fire.

What isn't defined is "premature". (Ask your wife/girlfriend! 😏 )

Plastic cable clips are not banned. Specifically, if you are clipping them to blockwork prior to boarding over, it is difficult to see how they could ever collapse. Even with clipped direct, it may suffice to have a non-inflammable clip every third one. Similarly, plastic conduit may require a metal saddle every third one. A normal plastic clip or saddle will provide satisfactory support under normal circumstances: the metal clips will prevent fire-fighters being trapped by fallen cables.

Re: 521.10.202

Posted by AJJewsbury on Oct 8, 2019 10:58 pm

Plastic cable clips!
Are they completely banned now?

No, not banned at all. Just can't be relied upon as a sole means of support.

What about vertical switch and socket drops which will be plasterboarded over? Would this situation be exempt?

No exemption needed - the plasterboard will do the necessary supporting, so the clips aren't the sole means of support.

  - Andy.

Re: 521.10.202

Posted by whjohnson on Oct 9, 2019 12:05 am

That's fine.
What about an inflammable means of support attached directly to a flammable surface? E.G.SWA clipped horizontally along a plywood-clad cellar wall? Or cables clipped to a timber floor or ceiling joist?
Am trying to envisage a scenario where despite the use of inflammable clips, the thing falls over simply because of something which has not been thought through.

Re: 521.10.202

Posted by lyledunn on Oct 9, 2019 7:59 am

No doubt that Mr Pearson’s wife/girlfriend could define premature but in common parlance and without stated parameters, the meaning will be subjective. However, when one considers the intention of the regulation then an approach to the matter of securing cables can be better assessed. Electricians should be capable of applying reasonably informed judgement as to whether their  wiring systems are secured to prevent premature collapse in the event of fire. 

Re: 521.10.202

Posted by John Peckham on Oct 9, 2019 11:37 am

Chris


I have asked both my wife and girl friend and they are both unable to define or give an example of the term premature.

However in terms of premature collapse of wiring systems I have previously sought advice on the from an ex senior fire officer now fire risk assessor. His view was premature collapse was when elements of the building were failing because the fire was so extensive or hot.Prior top that stage would be the rescue stage for firefighters where they would be going in to a premises on fire with breathing apparatus to search for and rescue occupants. If due the excessive heat elements of the building were collapsing it would be to hot for the firefighters to enter and anyone who was trapped inside would be dead anyway. If that was the case they would fight the fire from outside the building squirting water in through the window apertures.

When the regulation was introduced in to the Wiring Regulations it was at the behest of the fire service as I think at the time 8 firefighters had been killed in 10 years mostly in residential premises. Because contractors were ignoring the definition of "Escape Route" as defined in Part 2 preferring to use their own definition to avoid having to implement the safety measure in the 18th Edition the term escape route was removed from the Regulation to ensure it was applicable without doubt to everywhere.

When this Regulation went in to the 17the Edition I was doing presentations on this at the Elex shows for Stroma. We were getting some people in the audience who were clearly not happy with this and questioned the need for this safety provision. At one Elex show after some objections from the audience a member of the audience put is hand up and said in addition to being an electrician he was a retained fire fighter and went on to say "this is killing my mates please do this" which stopped any further questions from the audience.

Every support does not have  to be metallic perhaps every third support if in your judgment it would be sufficient to prevent the cable falling down and trapping someone. There a loads of solutions from the manufacturers and suppliers for every type of cable and situation so there is no excuse not to do it, come along the the Elex shows (next one Sandown Park in November) and have a look at the solutions on display there.

Re: 521.10.202

Posted by Alasdair Anderson on Oct 9, 2019 12:04 pm

whjohnson:
What about an inflammable means of support attached directly to a flammable surface? 

You have to be careful with your use of terms - unfortunately 'inflammable' means the same as 'flammable'. What you mean is "a non-flammable means of support" (which I admit is obvious from your following sentence). I just raise this to make sure you don't accidentally specify an inflammable means of support and have no recourse when wood is used.
(For information: inflammable = something which can be inflamed (set fire to) and flammable = something which can burn)
You may think this is being pedantic, but if the wrong word is used in a specification it can be a problem and the lawyers are far more pedantic than I am.
Alasdair

Re: 521.10.202

Posted by mapj1 on Oct 9, 2019 1:47 pm

I think from the example of the clips onto plywood, the idea is to ask 'what if the substrate is to some degree flammable?'
The key here is the premature collapse part - actually wood is not that fast to burn, even a light weight plywood door is capable of holding a fire off for several minutes, and joists and cladding actually add vital tens of minutes of rescue time.
So what is needed ?
Firstly ask can the cable fall anywhere if the clips fail ? - if it is already at floor level, or droops a bit but stays well above head height and is then trapped by other structural elements, then it is not an issue. The fact that those other elements will eventually fall sets  a cut off time, as  by then a rescue is either all over, or no longer possible.
If however long before the woodwork has burnt through, the cable has dropped to a level where it creates a lethal sticky garrote, then this is the situation to be avoided.
By far the worst are things like plastic trunking running under a ceiling, as once it softens it drops everything, leaving the screws behind.
I suspect that plastic clips nailed upwards into any substrate ,even a flammable one, are not really on as the sole means of support, as with heat from below, the plastic will always soften well before the ceiling ignites.
 
regards Mike

Re: 521.10.202

Posted by Chris Pearson on Oct 9, 2019 2:27 pm

Alasdair Anderson:

whjohnson:
What about an inflammable means of support attached directly to a flammable surface? 

You have to be careful with your use of terms - unfortunately 'inflammable' means the same as 'flammable'. What you mean is "a non-flammable means of support" (which I admit is obvious from your following sentence). I just raise this to make sure you don't accidentally specify an inflammable means of support and have no recourse when wood is used.
(For information: inflammable = something which can be inflamed (set fire to) and flammable = something which can burn)
You may think this is being pedantic, but if the wrong word is used in a specification it can be a problem and the lawyers are far more pedantic than I am.
From the OED: "1959   Gloss. Packaging Terms (B.S.I.) 10   In order to avoid any possible ambiguity, it is the Institution's policy to encourage the use of the terms ‘flammable’ and ‘non-flammable’ rather than ‘inflammable’ and ‘non-inflammable’."

The use of "flammable" was very much frowned upon at my school, but OED allows it as a synonym for "inflammable" which is much the older word.

Re: 521.10.202

Posted by burn on Oct 9, 2019 2:45 pm

Chris Pearson:
No and yes.

This topic came up during my annual assessment last week. We were agreed that cables clipped direct at waist height (e.g. in a workshop) are unlikely to present a hazard in the event of fire.

What isn't defined is "premature". (Ask your wife/girlfriend! 😏 )

If the wall was 30 minutes fire rated, I would suggest the cable fixings collapsing less than 30 minutes would be classed as "premature" 
burn

Re: 521.10.202

Posted by MHRestorations on Oct 9, 2019 10:19 pm

What is often missed by other trades is that this regulation covers ALL types of wiring, not just power and lighting. It includes CCTV, data, telecomms, alarm wiring etc. 

On a job we're currently busy with the alarm installers were true professionals, using metal clips etc, and their routing was neat and a joy to behold.

Openreach, notsomuch

Re: 521.10.202

Posted by whjohnson on Oct 10, 2019 12:02 am

Folks I thank you for your input. And you are correct to pull me up on the use of the incorrect term "inflammable"! I put it down to a senior moment and should know better!

All my wholesaler stocks in terms of fireproof fixings (see what I did there!) is enamel paint coated steel builder's band. from them - It works out at around £10 inc vat for a 10 mtre roll.
Of course, they stock galv conduit saddles and the like, but I would imagine that the use of these would be frowned upon when hanging a bunch of T&Es - "Good workmanship and materials shall be used".
Buckle clips can still be had online but they are not cheap - around £20 for 100.
I wonder if Gas Safe have introduced similar constraints for plastic clips used with either plastic or copper pipe runs?
 

Re: 521.10.202

Posted by MHRestorations on Oct 10, 2019 1:17 am

https://www.screwfix.com/p/schneider-electric-thorsman-fire-cable-clips-for-twin-earth-cable-1-2-5mm-silver-100pk/767gv  are a bit pricey, but they satisfy your demand for good workmanship. If the cable is on view I'd go for those. If it's not (eg above a ceiling), then go for the banding. I've used it with no qualms. A woodscrew buried 1 1/2 to 2" into a joist is not going to collapse prematurely.

if it's a 'bunch' of T&E's, the band is the way to go. Good fixing into stuff that's not going to melt. (check what kind of wall plugs you're using if 'upside down' ... a normal rawlplug with a 2" screw won't fall out even in a fire if on a vertical wall, but if hanging from a concrete ceiling, more thought needs to be taken)

Don't forget to take into account the grouping factors!

I suspect those buckle clips AND the thorsman type will drop in price as awareness spreads (hope?)

Re: 521.10.202

Posted by mapj1 on Oct 10, 2019 9:05 am

I wonder if Gas Safe have introduced similar constraints for plastic clips used with either plastic or copper pipe runs?

Well the relevant standards in the UK do not permit plastic pipes in fixed indoor gas  work, only underground.  (hoses for free standing appliances tend to be  butyl  or nitryl rubber, which will combust at high temperatures)
While metal clips for gas pipes sound like a good idea, while we allow soft soldered joints indeed prefer them over compression fittings, there is a problem at well below wall ignition temperature, as the solder at the joints melts at about 230C.
Actually in some parts of the world with more gaswork than the two or three appliances per house common in the UK,  hard solder (more like brazing temperatures of 600C or so ) is required for domestic pipework, and soft solder has gone the way of the old lead pipe and is no longer permitted.

In practice however, the accident rates are comparable, falling gas pipes are rare,  perhaps partly because there are far fewer gas pipes clipped to ceilings than there are cables.

regards Mike

Re: 521.10.202

Posted by whjohnson on Oct 10, 2019 5:43 pm

In the context of the thread Mike, I was thinking more along the lines of rigid copper pipework presenting the same physical hazard as a cable would to firemen attempting access where the melting clips would allow the pipework to fall and present a dangerous obstacle/trip hazard for example.
There is also the problem that fallen half-melted lengths of plastic pipes present in the same way as plastic trunking?

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