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Topic Title: Fire alarm cabling - door hold open units.
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Created On: 21 April 2013 03:45 PM
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 21 April 2013 03:45 PM
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Smith249

Posts: 362
Joined: 09 September 2004

Hi guys,

We have been asked to first fix the fire alarm cabling on a job as part of other works with the fire alarm company carrying out the second fix. We have a meeting with the fire alarm company next week prior to the work starting but I just want to be a bit more clued up before hand as I haven't ever installed the supply to door hold open units - these are the type which are built into a door closer with a cable coming off them.

Is the normal way to do this to run a separate fire rated cable from the fire panel and loop in and out of all the door units? - are these units normally powered from the fire panel on 24v via an aux relay then when the fire alarm triggers it drops the 24v to the units? - also what would you expect the max run for these on 1.5mm FP200 type cable and what would be it's limit before going to 2.5mm

Any advice on this would be appreciated so I have a better idea before the meeting.

Many Thanks.
 21 April 2013 03:56 PM
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nlasen

Posts: 164
Joined: 23 December 2006

Some are run that way and others have a local power supply serving sevaral units and then a fire alarm interface. to break the feed to the hold open which will then close

The thing to establish with the fire alalrm people is whether there are any release buttons required at switch height to enable the doors to be closed manually.

A lot of fire alarm companies prefer to use another power supply as the panel is not rated to run a lot of door hold opens.

They will be able to advise you once you have a meeting with them.

All cabling to be in FP200 or equivalent is the norm

Nick
 21 April 2013 03:59 PM
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OldSparky

Posts: 592
Joined: 28 June 2011

howdy

they generally are fed from their own power supply, possible with batt back up.

There will be a pair of terminals in the FA panel to trigger the release of the doors.

i suppose the size of cable would be determined by the length of run. but they are low powered so you could go a long way. depends if they are mains ones too?

piece of cake.

who is doing the FA?
 21 April 2013 04:15 PM
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Smith249

Posts: 362
Joined: 09 September 2004

The units have a rocker switch on the connection box so these can be used to release the doors I guess? as they are in reach. I was going to bring the FP200 cables to a 1 gang recessed box above the hinge side of each door with a blank plate. They can then fit the door unit cable to this as the small connection box that comes on the end of the units doesn't look big enough to take 2x FP200 cables - they can either mount this box adjacent to the blank plate or on the blank plate.

The very basic spec they sent me says 'The existing system is a 12 zone conventional system and that there are using the 2 remaining spare zones - 1 for the new upstairs elevation, 1 for the new downstairs elevation and that the existing sounder circuits will be used'. I take it from that it is not an addressable system so I need separate cables for upstairs and downstairs heads/call points?

From the panel location then I would run :-
1x FP200 looping around to all the required door positions
1x FP200 looping round to all the sounder positions
1x FP200 lopping around to the smoke heads and call points upstairs
1x FP200 looping around to the smoke heads and call points downstairs

The runs won't be more than 150 meters I wouldn't of thought.

Would you advise putting recessed metal BESA boxes in the ceiling for the smokes with the FP200 glanded into them from behind for support of the sounder and extra wiring space or would you just leave the 2 cables hanging out the plasterboard for them to fix the sounder direct?

Most of the wiring is above the plasterboard ceiling but there it needs to run outside for about 10 meters. I was going to do 2 runs in dual Pclips with brass screws however will the red fade in years to come, is this acceptable? steel conduit would be a real pain due to the wall surface.

Thanks again.
 21 April 2013 11:05 PM
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leckie

Posts: 1864
Joined: 21 November 2008

Pretty sure these can be 230v as well as 24v, or certainly used to be. Speak to or google cooper fire alarms. Whichever way, separate power supply, and use the fire alarm auxiliary contacts to remove the supply and thus release the doors. Switch by the doors also releases the doors.
 22 April 2013 10:12 AM
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OMS

Posts: 19668
Joined: 23 March 2004

From the panel location then I would run :-

1x FP200 looping around to all the required door positions

Check on the door equipment - it can be 24V or 240V and may or may not require battery back up - most normal is switching at a door (or group of doors). Check (as you have a conventional zoned system) if every door is to close on global comand or just selected doors protecting (and within) the zone of operation. On a conventional system, you will need to find the dedicated zone auxilary contacts per zone (or use a sounder circuit relay for global oberation). Cabling may or may not need to be fire rated. In many cases, doors should close on mains failure anyway - so non fire reated cable is common - don't fire rate a circuit that doesn't need it - it's akin to wiring self contained emergency lights in fire rated cable - it diminishes the system safety operation.

1x FP200 looping round to all the sounder positions

Nope - there will be either one, two or more sounder circuits present - if you have zoned sounder circuits then you'll need an additional sounder circuit for each new zone. If you have global sounder circuits (either a single circuit in the building and one at the panel or an interleaved pair of sounder circuits around the building, then you are going to have to find the existing EoL devices and extend from there. You cannot add a spur or "T" to a sounder circuit as you'll defeat the end of line monitoring.

1x FP200 lopping around to the smoke heads and call points upstairs

One per zone, yes

1x FP200 looping around to the smoke heads and call points downstairs

as above



Get a proper circuit map of what your employer wants - don't guess - you'll end up in a mess - and take acount of what the system is designed to do and my comments above. Agree the grade of cable required by BS 5839 - it may be normal or enhanced grade and that will lead you to the correct soft skinned cable - don't assume. I had a job ripped out recently because the contractor couldn't understand the difference in cable grades and assumed every soft skinned cable complied with both grades - so be warned.

Regards

OMS

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