Fire alarm mains supply

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The supply mains cable must be wired in a fireproof cable. An unswitched spur is not good enough for local isolation. You should fit a grid arrangement with a keyswitch and fuse to get the double pole isolation. I expect this will eventually filter through to all items that have an unswitched spur Even i got it wrong untill a couple of years ago.

 

fuze-box

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Yes, it should also have its own Isolator with mcb, ideally lockable or fish key type and not spured off from a socket or light supply, it should be labled "Fire Alarm Supply do not switch off", on a red notice board or Fade Free Durable sticker.

 
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Yes, it should also have its own Isolator with mcb, ideally lockable or fish key type and not spured off from a socket or light supply, it should be labled "Fire Alarm Supply do not switch off", on a red notice board.
I recently quizzed the NIC about this. I always used to fit a separate red switch fuse labeled 'Fire alarm, do not switch off'. I can find no reference to the separate isolator in either BS7671 or BS5839.

 

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BS 5839 25.2 c to f)

"To facilitate local isolation during maintenance, suitable means should be provided for double pole isolation of the low voltage supply circuit that serves the power supply and control equipment."

 
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