IET logo
Decrease font size
Increase font size
Topic Title: Need to move smoke detector
Topic Summary: wired system
Created On: 05 February 2013 09:18 PM
Status: Read Only
Linear : Threading : Single : Branch
Search Topic Search Topic
Topic Tools Topic Tools
View similar topics View similar topics
View topic in raw text format. Print this topic.
 05 February 2013 09:18 PM
User is offline View Users Profile Print this message


Posts: 512
Joined: 24 January 2008

Hi everyone

I need to move a smoke detector.
At the moment it is wired in FP200 in 25mm plastic conduit and is fixed to a concrete ceiling (surface)

The customer wants to fit a new lower plasterboard ceiling so the detector needs to be moved down about 400mm.

I want to remove the detector head and take the cables out of the conduit and then "poke" the cables through into the detector base once the new ceiling is fitted.

I only want to isolate that one detector as the other detectors/break glasses need to continue working.

Has anyone had to do this before? I know people will say get a Fire alarm company in to do it, but is it that difficult?

Many thanks in advance

 05 February 2013 09:26 PM
User is offline View Users Profile Print this message


Posts: 3715
Joined: 31 March 2005

removing the head will put the alarm into fault, which may or may not set it off bells ringing.
You need to find out the area which the alarm covers and make sure everyone knows whats being planned at a certain time, disable the alarm and take the head off. Get the conduit off just enough to slew the cable down the 400mm and reterminate the sensor EXACTLY the same as before and get the panel back in normal mode.
Leaving the head off will be a disaster otherwise.

Put it back into the new ceiling with a suitable metal galv conduit box glanded onto the cable above the ceiling with the sensor clamped into the board with some longish screws.

Edited to say only do it if your 100% ok with doing it otherwise get an alarm company to do it (yeah good luck with that one as they are a nightmare)

Lack of planning on your part doesn't make it an emergency on mine....

Every man has to know his limitations- Dirty Harry
 05 February 2013 10:25 PM
User is offline View Users Profile Print this message


Posts: 783
Joined: 09 March 2012

I got called out last week to look at a disabled call point, connected to a fire alarm panel.
The Company had called the fire alarm company to ask if they could come and have a look. Yes, they could, but at £300 plus parts.

I got the call, and repair job. £50 total cost. So, yes, fire alarm companies can be a nightmare,if you are a customer.
 05 February 2013 10:41 PM
User is offline View Users Profile Print this message


Posts: 680
Joined: 16 July 2011

what sort of system is it?

If its a conventional system you should have 2 two core cables to the base. Unplug the head, the panel will go into fault, go to the panel, enter the access code and push the "Mute Buzzer" button. cut the cable cores at the base and then pull the cable out of the conduit. If you are not going to reinstate the head there and then just connect the 2 blues together and the 2 browns together and twist the screens, ideally in at least a BE or Galv conduit box to give the joints some sort of protection. The panel should now go out of fault.

There is no need to disable the zone, but if you are really worried and want to look smart you can turn the mains supply off and drop the front of the panel and pull a lead of a battery

by the way remember if the cables are to be run surface (on the underside of the ceiling) they must be clipped using fire retardant fixings i.e. "P Clips" to prevent the cable from dropping down in the event of a fire and the plastic conduit melting. we usually use MMT 2 trunking and fix the cables through the trunking using P clips screwing through into joists where possible. You can either clip just one cable and attach the other cable to it using stainless tye raps or alternate the cables and fixings

Edited: 05 February 2013 at 10:48 PM by Dave69
 05 February 2013 11:54 PM
User is offline View Users Profile Print this message


Posts: 219
Joined: 10 January 2003

Most fire panels will have the ability to continue to operate when a sensor head is removed but the base is left connected in circuit. There is usually a bypass diode in the base which allows other sensors to continue working however, the fire panel may flag a fault in that zone.

If you are removing the base too, then perhaps do what Dave mentioned above.

M.I.E.T - Forfeited this due to The I.E.T's ridiculous membership rules!

New here?

See Also:

FuseTalk Standard Edition v3.2 - © 1999-2018 FuseTalk Inc. All rights reserved.