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FIRE SERVICE AND GENERAL FIRE SAFETY TOPICS => Technical Advice => Topic started by: Dean Mathias on October 17, 2005, 11:44:27 AM

Title: Question ? Recommendations for mains power supplies
Post by: Dean Mathias on October 17, 2005, 11:44:27 AM

Can any provide some Guidance

BS5839 pt 1 2002 section 25.2  C

To facilitate local isolation during maintainance , suitable means should be provided for Double pole isolation of the low voltage supply circuit that serve's the power supply and control equipment.

Can anyone suggest a suitable device ? as an un-switched spur outlet does not conform as it is single pole device.

Title: Question ? Recommendations for mains power supplies
Post by: David Rooney on October 17, 2005, 06:16:47 PM

Hi
MK make a double pole spur with an integrated "fish tail" key switch, same as the emergency lighting keyswitch.

MK K963 KOALM

I believe they also do them now in red specifically for the job.

Title: Question ? Recommendations for mains power supplies
Post by: Graeme on October 17, 2005, 09:30:28 PM

Make sure you ask for the tamper proof screw option if the unit is accessible to joe public.

on the fuse carrier

Title: Question ? Recommendations for mains power supplies
Post by: colin todd on October 20, 2005, 04:03:51 AM

Graeme, you do not need the fuse-it is an optional extra.

Title: Question ? Recommendations for mains power supplies
Post by: Graeme on October 20, 2005, 05:52:28 PM

The model David Rooney quoted was the one with a fuse.
I prefer them to the 20 amp key switches as they are not made in grid sections.
i'm just a young fuss pot

Title: Question ? Recommendations for mains power supplies
Post by: Graeme on October 20, 2005, 08:25:16 PM

Colin-more  jobs i am going to now have the fire system 240v supply from consumer units on their own circuit breaker.
I prefer to have a dedicated isolator but clause 25.2b states the circuit should be soley for the fire alarm system.
So going by that and making sure there is a local means of isolating at the cie that can be locked in the off and on position, i take it this method is okay?

I don't have any input or responibility for the supply apart from making sure that the relevant boards are marked with labels 1-3 where needed.

Title: Question ? Recommendations for mains power supplies
Post by: colin todd on October 21, 2005, 06:53:51 PM

Graeme, Yes that is fine. The old dedicated isolator is now a bit old fashioned. The arrangement you describe is the norm but you want to watch that there is not a 30mA rcd serving the whole board.

Title: Question ? Recommendations for mains power supplies
Post by: Graeme on October 21, 2005, 07:29:45 PM

thanks Colin.
I got a nice suprise today when i asked for a spark to install the supply for my new system.He had fire resistant cable with him and even p-clipped it above the false ceiling.
I'm glad he does not use fr cable alot as it must be the same drum he's had for years so it was red and black conductors which matched the rest of the retro-fit job after i had scoured the land for old colour cable for additional wiring that was required.

Title: Question ? Recommendations for mains power supplies
Post by: Dean Mathias on April 21, 2006, 09:52:59 PM

Sorry for taking so long to come back to everyone who replied, i am now using the mk device, i recently had a NSI audit for BAFE accreditation as was asked for the electricians test cert to confirm that the new dedicated supply had been tested and certified as safe !!