Extinguishing Project

[Allen Higginson]

Afternoon - just looking a couple of answers or confirmations (so no "well,I think it's best practice to...."!!).
(i) Do you have to install a "DP/switched via special key" isolator (as per 5839) or will a fused spur do?
(ii) There are external relays fitted (in enclosures) whose coils are switched by the extinguishing panels first and second stage contacts.
Is it acceptible that the cables from the panel to the coils are FP (or equiv.) but the cables going out on the contact side are wired in 6 core grey 0.6mm signal cable or do they all have to be in FP up the the point of final termination (ie - right at the connection on the equipment that it's shutting down)?

My answers are (i) the former and (ii) the latter!!

[Galeon]

Buzz IMO ,
Supply spur would be best to be d.p
As long as you have everything bolted together ie couplers and bushes , I would treat it as internal panel wiring . In relation to your shutdown(s) which may be supplied by others as long as its a closed contact , I don't see you have a problem.

[Allen Higginson]

Well,my point on this is that the shutdowns are on the machine that the system is protecting aon so are part of the actual solution a la -

"It is essential that all interconnections operate correctly at the time of a fire. This is particularly important in the case of cables that link control equipment to manual call points, automatic fire detectors and fire alarm devices, and that transmit signals to an alarm receiving centre. It is only less important in the case of interconnections between the fire alarm system and other equipment that are so arranged that failure of interconnecting cables during a fire would not lead to a dangerous condition (e.g. because the failure causes the other equipment to change state to that appropriate to the fire condition)."

The relay shuts down the adhesive being supplied to the coating head and the actual machine itself.

[David Rooney]

7273 pt 1

Clause 8.2 says

"The wiring of for the extinguishing system should conform to the recommendations given in BS 5839 pt 1:2002 Clause 26 for cables of standard fire resistance."

So I would take that to include the mains supply and means of isolation.

Also, 6266: 2002

6.3.2 Circuit integrity for risk Category D and Category E installations Where continuity of service from the electronic equipment is required for life safety reasons or to prevent unacceptable interruption to operations, additional precautions might be necessary to ensure that power and data cables are not unduly susceptible to damage by fire. Power cables should therefore be of a fire-resistant type, and conform to Category CWZ of BS 6387:1994.


So having carried out the RA, if the shutdown circuit is considered "critical" then the field wiring to which you refer should be fireproof......... in my opinion..