BS7671 applicability and loudspeaker suspensions.

521.10.202.  Wiring systems shall be supported such that they will not be liable to premature collapse in the event of a fire. That is all that I can think of. There may be building regs. that cover suspended equipment that may cause harm if allowed to fall. I know that suspended stage lighting for example has a main support and back up to prevent it crashing to the ground.

And, are ceiling speaker fire hoods required?

134.1.1 Good workmanship and ...take account of manufacturer's instructions.

Looooooooooooook.....www.toa-products.com/.../f-122cu2_mt1e.pdf

Z.

Good point on the manufacturer's instructions.

I think the query originates from a commercial rather than domestic installer, where a suspended tile ceiling doesn't normally form a fire barrier (unlike the plasterboerd ceilings 'protecting' a timber floor above) but definitely something else to consider.

Agree about the need for the wiring systems to be adequately supported, but I can't stretch a loudspeaker into a definition of a 'wiring system!'

The secondary suspensions for theatre equipment are largely based on systems where fly bars are used and a hook clamp could be easily caught and lifted off by a piece of scenery flying past on an adjacent bar.  After a few things fell down it became a requirement for the secondary to be applied and it has stuck in almost all situations even though rigging methods have evolved in many cases and it is used commonly where there is no risk of an item being lifted off it's mounting.  Not that having a secondary there is a bad thing though.

I'm with zoomup on this one - I don't know of any direct BS 7671 requirement that light fittings (or any other accessory) need any secondary support - it's just wiring systems must not collapse prematurely in the case of a fire. There might be an implied requirement that the weight of the fallen fitting shouldn't pull down the wiring connected to it - which might be easier to achieve by supporting the fitting rather than beefing up the fireproof cable supports, but that sort of detail is up to the designer rather than any blanket BS 7671 requirement.

   - Andy.

A wiring system is an assembly made up of cable or busbars etc. See definitions.

Full details of the installation are unknown.

onepullwire.com/.../

Z.

The requirment in BS7671 is because cables have been known to fall and tangle up firemen. It is not that all items may fall, this is always true, but that becoming entangled has been found to be a significant danger.

As far as the theatre equipment, the safety bonds (cables or wires) are used because the fixings are by their nature temporary, often a single bolt for lanterns, and these may not be tight, or stay tight during use. Fixed items like support bars or truss do not have the same requirment, they are fixed by stable equipment, and even hoists, to allow them to be moved or lowered, and these are designed to be failure proof as far as possible. It is not reasonable to compare a single bolt (loose or otherwise) with arrangements which comply with crane (LOLER, lifting operations and lifting equipment) regulations. Typically these items have factors of safety of 6 (failure may occur at 6 times the rated load), and are thus safer than structural steelwork or other things we consider safe. Often people are surprised at the relitively low SWL of obviously strong items like shackles and wire ropes used for lifting, and even chains look quite large (although tested chains may have a lower safety factor). As with electrics, the important part of safety is inspecting the equipment regulary for any problems.

Thanks David - leaving aside the entanglement issue, so you have a view on if BS7671 has a requirement for secondary suspension of loudspeakers (I don't think it does), or if a loudspeaker would fall within the definition of 'equipment' under BS7671.  They require a source of electrical energy - it just (usually) comes out of an amplifier!