Smoke Detector Wiring

[bilbo_88]

Hi All

Just a quick one. Recently had a job to install inter linked smoke detectors in the communal area of a house converted to 2 flats. Health and safety requested standard mains powered smokes with interlink.

I wired this through floors in T+E as I would in a standard domestic property, but have been pulled by another electrician stating it has to be in FP200. I have wired these from the lighting circuit (also wired in T+E) and used radio link bases so wiring it in FP200 seems pointless and pretty harsh reason to fail an EICR?

Any opinions and reg references are appreciated

 

[westward10]

Ask what Reg you have breeched. Are the cables exposed on the escape routes.

 

[Octopus]

Is the T&E visible? surface mount?

Is the property going to be a HMO?

 

[bilbo_88]

Cable Is in surface mounted trunking with fire clips inside. Not a HMO, literally upstairs and downstairs landing with front door to each flat on each floor

 

[westward10]

Cables on escape routes should be avoided however not prohibited and should be kept as short as possible if it is necessary. Even if the cable were low smoke the trunking is not and I probably would have used FP. Are you being told why it is not suitable.

 

[Specialist]

Might be wrong (Happened before) but don't the rules class a house where 2 or more people live & that are not related as a HMO ?. So although it's been subdivided inside, it may still class as 1 house as with bedsits.
Think I'd be asking the local authority what they class it as.

 

[charlie76]

What grade of system is it?

 

[charlie76]

From BS5839-6:2013 it sounds like what you have put in is a grade D system, this should however have been communicated to you at tender stage by the specifier. It is implied by the equipment they have told you to install but you should confirm this. If this is the case (Grade D) then BS5839-6:2013 clause 16.5 a) states that "may comprise any cable suitable for domestic mains wiring"

 

[westward10]

Don't think the type of system is relevant it is the wiring method on an escape route. Be interesting to know the comment on the EICR

 

[charlie76]

Don't think the type of system is relevant it is the wiring method on an escape route. Be interesting to know the comment on the EICR

If it were a grade A, B or C then he would be using FP. The wiring method described in BS5839-6:2013 states that it should be installed as per BS7671 which doesn't ask for FP on escape routes.

 

[Ian1981]

Where non metallic cable trunking is used in escape routes suitable fire resistant means of support can be used inside the trunking
Regulation 522.11.201 so can't see the problem if pvc conduit/ trunking is used as long as it has metallic supports for the internal wiring.

 

[charlie76]

Where non metallic cable trunking is used in escape routes suitable fire resistant means of support can be used inside the trunking
Regulation 522.11.201 so can't see the problem if pvc conduit/ trunking is used as long as it has metallic supports for the internal wiring.

Thats right. Be aware though how you fix the internal metallic supports to the building fabric. We recently had an LPCB inspection and they no longer accept plastic plug and screw as a fire resistant method of supporting anything on an escape route. They are now expecting metal rawl plugs or frame fix type screws without a plug. In tests they carried out, plugs melt and drop.

Same goes for surface P clipping or saddle clips they expect metal plugs or frame fix screws.

See attached.

 

[westward10]

Nothing to do with cable fixing but flame propagating systems on an escape route, not at home to check Regs though.

 

[Ian1981]

Thats right. Be aware though how you fix the internal metallic supports to the building fabric. We recently had an LPCB inspection and they no longer accept plastic plug and screw as a fire resistant method of supporting anything on an escape route. They are now expecting metal rawl plugs or frame fix type screws without a plug. In tests they carried out, plugs melt and drop.

Self drilling masonry screws are the way forward.

 

[Ian1981]

Nothing to do with cable fixing but flame propagating systems on an escape route, not at home to check Regs though.

That regulation mentions absolutely nothing about flame propagating systems just supports.
Pvc containment is not prohibited as long as cables have metallic supports to prevent premature collapse.
Regulation 422.2.1 which can mean LSoH cables

 

[westward10]

Think we are at odds with different Regs, I get the cable fixing bit but it is the use of flame propagating materials on an escape route can't check it out at the moment.

 

[Midwest]

Last NIC/Elecsa 'web in air' vid I watched, Cable & Stantiforth stated the use of 'plastic plugs' were still deemed to be acceptable in such situations, it was the 'clip or fixing' that has to be metal or fire resistance. Seems, their advice comes from some document or study, suggesting the plastic rawplug, would survive fire due to the surrounded concrete or brick structure.

Once again, these 'organisations & bodies' need to have some sort of joined up thinking, and stop offering conflicting guidance.

Or is it the case, some manufactures sense a marketing opportunity.

 

[Octopus]

Once again, these 'organisations & bodies' need to have some sort of joined up thinking, and stop offering conflicting guidance.

I've just seen a pig flying past the window.... and IF, I say IF the IET got its act together, the "variety" of interpretations wouldn't be required..

 

[Midwest]

I've just seen a pig flying past the window.... and IF, I say IF the IET got its act together, the "variety" of interpretations wouldn't be required..

We can all live in hope, even in utopia

 

[westward10]

That regulation mentions absolutely nothing about flame propagating systems just supports.
Pvc containment is not prohibited as long as cables have metallic supports to prevent premature collapse.
Regulation 422.2.1 which can mean LSoH cables

422.2.1 states wiring systems shall be non-flame propagating. It is there in black and white.

 

[Wilko]

Fresh back from a few days away, I'm tempted to ask "so would normal cable be flame propagating ? "
Fire rated cables I get, but is that the same as non flame propagating ?
May need to duck off back to Heidi Land

 

[westward10]

Think people are so blinded by Am 3 and fire resistant fixings they ignore the requirements for cable systems on escape routes and T&E most certainly would not comply even if it were fixed with indestructible clips. Comment frequently when doing FRAs on this type of thing.

 

[bilbo_88]

Ok great, thanks for all your advice guys. And for those who were asking it was a grade D system

 

[Ian1981]

Try non fire propagating pvc conduit to bs en 61386-1
Bs en 50085
Bs 4607
All expectable in escape routes.

Winner rating??
Are we still in school??

 

[Wilko]

Reading that 422.2.1, towards the end it does say for BD2/3/4 the wiring systems shall be fire rated... (edit : just read Ian post #24 )
I did set fire to a cable to see what happened - not as bad as I'd hoped thought with the cable self extinguishing within about 10sec. Not surprising it failed IR testing after meeting Mr Rothenberger. Now for the pics

 

[Ian1981]

Reading that 422.2.1, towards the end it does say for BD2/3/4 the cables shall be fire rated...
I did set fire to a cable to see what happened - not as bad as I'd hoped thought with the cable self extinguishing within about 10sec. Not surprising it failed IR testing after meeting Mr Rothenberger. Now for the pics

View attachment 36346

Try that with LSOH cable which is non fire propagating and will not give off the fumes standard twin & earth will

 

[westward10]

Ok great, thanks for all your advice guys. And for those who were asking it was a grade D system

So what did the EICR say.

 

[bilbo_88]

So what did the EICR say.

FP200 not used for smoke detectors- C2

Had no regulation reference or anything

 

[Ian1981]

FP200 not used for smoke detectors- C2

Had no regulation reference or anything

Potentially dangerous???

 

[Octopus]

Potentially dangerous???

No - C3 maybe?

 

[Ian1981]

No - C3 maybe?

I would say it's more to do with a fire alarm service report issue and not a eicr.
You could note it on the eicr in comments if there was an issue but bs 7671 don't cover fire alarms.
Bs 5839 -1
Bs 5839-6 for dwellings

 

[westward10]

FP200 not used for smoke detectors- C2

Had no regulation reference or anything

I would contact them and ask their reasons. A Grade D system does not need fire resisting cable unless the requirements of BS7671 could only be met by doing so. I find it unlikely, though not impossible the reason is for an inappropriate wiring system on an escape route. More likely they have misread BS5839-6 or confused it with BS5839-1, the fact they have given a Code 2 is neither here nor there and it would be interesting to know why they have picked up on it to resolve your problem.

 

[davesparks]

Reading that 422.2.1, towards the end it does say for BD2/3/4 the wiring systems shall be fire rated... (edit : just read Ian post #24 )
I did set fire to a cable to see what happened - not as bad as I'd hoped thought with the cable self extinguishing within about 10sec. Not surprising it failed IR testing after meeting Mr Rothenberger. Now for the pics

View attachment 36346

fire will tend to travel upwards rather than down so you have it biased towards self extinguishing there. If you did it again but set fire to the bottom of a vertical section of cable you might get it to burn a bit longer.

 

[charlie76]

An interesting read if you have 10 minutes spare.

 

[tazz]

We are going off in a tangent here..lol
Domestic fire detection must meet BS5839 part 6 & BS 7671. Grade D can be wired from the consumer unit or from a local light fitting, in normal T&E. If specified then LSOH. As with emergency lighting, the units contain back up batteries. So the cable is sacrificial. The units also require a screwdriver to remove from the base, giving total isolation from mains, complying with the lockable isolation rule. Grading such as A,B,or C utilize a central psu, or control panel so the cable now becomes and issue to supply as long as possible. So here FP or Pyro would be required.