When you fire rate a ceiling you measure the amount of time it can hold back a fire before it spreads to the floor above. But what happens when you cut a hole in a ceiling to fit recessed lighting?
According to Neil Perdell, a technical services manager, you immediately compromise that ceiling's fire rating and contravene a number of regulations.
Q
Why does a recessed light pose a fire risk?
A Most premises have fire-rated ceilings. This is the amount of time
that a ceiling can hold back the fire before it spreads to the floor
above. A fairly typical fire rating for a ceiling is 60 minutes. Of
course, when you cut a hole in a ceiling to fit recessed lighting, you
immediately compromise that ceiling's fire rating. The gaps within the
light fitting will now be that ceiling's weakest point. Flames, smoke
and heat will find that gap and pour through it, spreading the fire
to the floor above.
Q
Won’t the light fitting fill the hole and restore the integrity
of the ceiling by itself?
A Almost certainly not. Conventional fluorescents and downlights are
not designed to fit seamlessly into a ceiling. No matter how good a
job of installation you make, there will still be a gap - and the fire
rating of the ceiling will still be severely compromised.
Q
Must a ceiling's fire integrity be restored after lighting is fitted,
or is it optional?
A The answer put simply is yes! The Building Regulations 1991 Approved
Document B Fire Safety 2000 Edition Section 11.2 (applicable in England
and Wales) says: 'If a fire separating element is to be effective, then
every joint, or imperfection of fit or opening to allow services to
pass through the element, should be adequately protected by sealing
or fire-stopping so that the resistance of the element is not impaired'.
The IEE Wiring Regulations 16th Edition BS 7671: 2001 Section 527-02-01
says: 'Where a wiring system passes through elements of building construction
such as floors, walls, roofs, ceilings, partitions or cavity barriers,
the openings remaining after the passage of the wiring system shall
be sealed according to the degree of fire resistance required of the
element concerned (if any)’. In other parts of the UK The Building
Standards (Scotland) Regulations 1990, Amendment 5, 1999, Technical
Standard Part D or The Building Regulations (Northern Ireland) 2000,
Technical Booklet E would apply.
Q
How can a ceiling's fire rating be restored?
A Ideally, every luminaire in a recessed light fitting should be fitted
with a fire protection cover to BS476:
Pt.23.
Q
How can a fire protection cover restore a ceiling's fire rating?
A A fire protection cover prevents both flames and heat being transmitted
through the luminaire up into the ceiling void. Usually these covers
have a 60 minute rating, which will be in keeping with a typical ceiling
fire rating, although the best can last up to two hours.
Q
When is the best time to install a fire protection cover?
A Obviously, the best time to fit a fire protection cover is at the
time the lights are being installed, but they can also be retrofitted
quite quickly and economically.
Q
What kind of fire protection covers are on offer?
A Several types of fire protection covers are now available - the woven
cloth types and fully intumescent 'caps' which simply drop over the
fitting. Both can be highly effective in stopping fire, although the
'cap' design is seen as being quicker and simpler to install both in
new applications and in retrofits. Being fully intumescent, it swells
to over three times its thickness in the event of a fire and is therefore
particularly effective in minimising the transmission of heat, as well
as flames. Both types are readily available from selected electrical
wholesalers and models are available for use with both downlights and
fluorescent modules.
Q
Do fire protection covers put any extra strain on ceilings?
A No. They're very lightweight and suitable for use with all ceilings,
including plasterboard and suspended ceilings.
Q
Is it true that fire protection covers can also help with the acoustic
performance of a ceiling?
A Yes, but only some types. When recessed lighting is installed, it
compromises the acoustic rating of a ceiling in just the same way as
it does the fire rating. Sound bleeds through the gaps. UK Building
Regulations Approved Document E now requires that adequate steps are
taken to prevent this transmission of sound from one part of a dwelling
to another. Good quality Fire Protection Covers can solve the problem.