fire alarm 230v supply

[D Skelton]

Oh, and while I'm at it, I shouldn't even be replying to this thread, mutiny an' all that...

I've said my piece so I'm off! till October that is.

 

[stranded]

Oh, and while I'm at it, I shouldn't even be replying to this thread, mutiny an' all that...

I've said my piece so I'm off! till October that is.

Ah, good point. Forgot about that. Cant keep away from this place...

 

[tazz]

I am becoming fed up of tying to help you guys out...we have wiring regs and fire regs...they both work hand in hand, and are written by the same guys....stop being know it alls of little knowlege....this is wriiten in the BS5839 part 1 of fire installation....supply will be in enhanced fire cable cable to a lockable double poled switched fused spur adjacent to the fire alarm control panel.....end of

 

[davethsparky]

Not end of though really is it? Or are we not allowed to ask questions and attempt to find out the reasoning behind the regulations? I know independent thought is terribly out of fashion these days. Or are you happy to blindly follow regulations without seeking to understand them?

 

[tazz]

Not end of though really is it? Or are we not allowed to ask questions and attempt to find out the reasoning behind the regulations? I know independent thought is terribly out of fashion these days. Or are you happy to blindly follow regulations without seeking to understand them?

i would be happy to...but please remember these are the standards....

 

[davethsparky]

I think we all know that these are the standards, at least I hope we do. But the rule in question here does certainly seem to be a bit daft on the surface of it, but then with a decent discussion we could find out why it may not be so daft

 

[tazz]

No reply...ok this is a standard to protect the supply cable for 30-40 mins....then our calculations of 24 hours standby and 30 mins alarm take over, these standards are to protect life and property

 

[davethsparky]

I should say at this point my knowledge of fire alarms is very little indeed, but I don't think that affects this discussion, I accept that the BS requires it and am not suggesting that it should not be installed that way. I am seeking to understand why the BS requires it to be that way.

I take it from your post that the standard requires the mains supply to the panel to be maintained in the event of a fire somewhere along its run for a minimum of 30 mins with an option of 40 mins (I assume this is situation dependant). My question is why is this required? My assumption would be that the 30 mins of mains plus 30 mins battery alarm gives a full hour of the alarm sounding, is this close?

The question of what happens if the fire is further upstream than the supply cable was raised earlier. Lets say the DNO cutout has a loose connection and starts a fire, as a consequence the tails suffer fire damage rather quickly and make contact and take out the fuse. Relatively plausible I think. The fire rated cable feeding the panel hasn't helped much there has it?

One argument I can see is that it is better to have the largest amount of the supply fire proofed as possible, but I wonder if there is any other argument?

Thinking about it a bit more, how long does a DB survive in a fire? assuming its metal clad and the door is shut properly that is? Does it already meet the 30 minute requirement?

 

[tazz]

The idea is to meet the the best possible length of time possible...using enhance cabled will prolong the suuply to the control panel....the next is the correct calculation on zone/loop supply of the control panel to meet or prolong the battery time to produce minimum of 24hrs standby and 30 minutes of alarm....anything more is a bonus when dealing with life protection.
Any cable suppling any appliance needs to meet the required wiring standard, and if this was to cause a fire within itself, would therefore not meet any standard.

 

[davethsparky]

If the idea is to achieve the best possible length of time then why is FP200 acceptable when MICC would surely give a longer time?

Am I right in saying there are still certain places where MICC is the only cable allowed (london underground rings a bell)?

 

[tazz]

Micc is far superior but we are talking abaut pf200 enhanced there is a difference...Lul now accepts pf200 standard as long as it is enclosed in containment as additional protection

 

[davethsparky]

I shall have to read up on the enhanced version then and see what's so special!

Is it cheaper to put fp200 into conduit than to use micc? And could you use fp100 in the conduit or would that go against the fire alarm standards?

Also does the conduit have to be red? As I said I don't get involved in fire alarms but I've always wondered about that one. I know some places get obsessive about red cables and mini trunking etc whilst other places I've seen the red fp200 clipped in its own compartment of multi compartment white trunking. ( I'm not so daft as to not understand the support with fireproof clips thing)

 

[tazz]

Ok pf100 is fire proof singles idea is to used in containment, fp200 is fire proof with protective cover. As an old designer for lul, micc was to cost us millions, yes it needs supporting as fp200 with fire proof copper clips, but removing old micc off tiled walls which were listed, required cold glazing to repair the screw holes. Very expensive job. LUL now consider all lighting, power , fire and PA be installed within purposed built, and very fancy central running segragated containment. Main idea on colour coding is red for fire, white for data pa, oragne for 230v mains. Conduit itself does no require to be coloured red, but as all cables in commercial use, need to be supported, hence tray or box trunking....if you can imagine a fire in you local supermarket, with cables falling down in a fire condition, would not be a good event. This also goes for plumbing and air conditioning, where pipes now need to be properly supported

 

[davethsparky]

I would imagine the removal of any form of cable from the tiled walls would have caused the same problem though? Or indeed anything at all that was fixed to them.
Sometimes the whole 'listed' thing just gets ridiculous.

 

[tazz]

Totally....now the central purpose built containment sorts this problem out. As you can see now on most tube stations, a very fancy coloured containment runs very nicely down the centre of all passage ways, esculators and platform levels, which is idea for lighting pa etc.......coming across old disused stations is the most interesting being listed, you cannot touch anything, including 1950`s chocolate and 1p weighing machines and wall posters
Must admit, do miss working on underground...lol