EP2166283A1

EP2166283A1 - Fire and smoke resistant covers for electrical fittings

Info

Publication number: EP2166283A1
Application number: EP09252194A
Authority: EP
Inventors: Derek Alfred Ward
Original assignee: Intumescent Systems Ltd
Current assignee: Intumescent Systems Ltd
Priority date: 2008-09-22
Filing date: 2009-09-16
Publication date: 2010-03-24
Also published as: GB0817396D0; GB2463533A

Abstract

A ventilated cover for use with a separate ceiling mounted downlight comprises an open ended metallic sleeve (1) having a layer or coating of an intumescent material on its internal and external surfaces and at least two opposed side openings (2) positioned to register with locating arms (8) of a downlight. A lamp holder is supported by a bracket located above the uppermost open end of the sleeve and the height of the bracket above the sleeve is adjustable.

Description

This invention relates to ventilated covers for electrical fittings and more especially but not exclusively to a ventilated cover for a recessed electrical light fitting positioned in a plasterboard ceiling, the cover, in the event of a fire, isolating the light fitting to maintain the fire and smoke integrity of the celling. The invention further relates to such a cover in combination with an electrical light fitting.
Light fittings recessed into ceilings are well known. Such light fittings are known as downlights. These generally comprise a lamp socket connectable by wiring to a mains source of electricity. The fitting conventionally has spring-loaded arms which co operate with the upper surface of the ceiling to retain the downlight in its required position. The lamp socket is normally positioned above a hollow seating having an upper sleeve which, in use, passes through and defines a close fit with the periphery of the downlight receiving hole formed in the ceiling and a lower outwardly extending annular flange which, in use, lies below and in contact with the underside of the ceiling. The heat generated by such a light fitting can be considerable and can in itself represent a fire hazard. Furthermore, the recess in which the fitting is mounted can provide a path for smoke and fire to a room or space located above that ceiling.
Fire resistant covers for downlights are well known, examples being disclosed inter alia in our UK patents 2297609 and 2325728 . Such covers are formed separate from a downlight to be protected and consequently need to be carefully positioned over and spaced from the exterior of the downlight during installation. The upper surfaces of these covers are closed apart from an intumescent gasket through which electrical cabling can pas and rely on fixings into the ceiling structure to retain the downlight in place. In practice correct alignment with respect to a downlight can be difficult particularly where access to the ceiling space is limited. Furthermore, fixing a cover to a ceiling can be difficult and can detract aesthetically from the decor of the ceiling.
A cover which forms an integral part of a downlight is disclosed in our UK patent 2326467 . In this arrangement the downlight casing has a frust-conical reflector positioned within a fabric hood coated or impregnated with a liquid based intumescent material. This cover avoids the alignment problems discussed above. However, having a cover formed integrally with a downlight has proved to be expensive with each cover of necessity serving only one species or a limited range of downlights.
Our co-pending application GB0715535.1 discloses a ventilated cover for use with a separate ceiling mounted downlight. The cover includes an open ended metallic sleeve having a layer or coating of an intumescent material on its internal and external surfaces and at least two opposed side openings. The dimensions of the sleeve are sufficient for it to fit over a downlight and the side openings are positioned to register with locating arms of the downlight.
This invention seeks to provide an improved ventilated cover for a downlight which can readily be adapted to accommodate downlighs fitted with either conventional or energy saving lamps.
In one aspect the invention provides a ventilated cover for use with a separate ceiling mounted downlight, the cover comprising an open ended metallic sleeve having a layer or coating of an intumescent material on its internal and external surfaces and at least two side openings positioned to register with locating arms of a downlight, and a lamp holder supported by a bracket located above the uppermost open end of the sleeve and means for adjusting the height of the bracket above the sleeve.
The bracket preferably has two downwardly extending supporting arms each formed with an open ended slot which locates over an adjustable fixing which projects outwardly from the external surface of the sleeve.
The sleeve is preferably produced from steel and may be of a constant diameter or cross section throughout its height. The gauge of the steel is typically 1mm.
Preferably the intumescent material comprises fibrous strips or pieces of intumescent material adhered or otherwise fixed to the internal and external surfaces of the sleeve. The strips or pieces preferably extend around or substantially around the entire internal and external circumferences of the sleeve to define rings of intumescent material. The internal ring of intumescent preferably extends from the uppermost rim of the sleeve to a position between one third and one half of the sleeve height. The external ring of intumescent preferably extends from the lowermost rim of the sleeve to a position between one third and one half of the sleeve height.
The side openings may extend from positions adjacent the lower and upper margins of the internal and external intumescent rings respectively. Alternatively, the openings may extend to the lowermost rim of the sleeve to define open ended slots.
In another aspect, the invention provides, in combination, a downlight and a separable ventilated cover for resisting the passage of flames and smoke in the event of a fire, the downlight including a lamp socket connectable to a source of electricity and at least two spring loaded arms which, in use, bear against the upper surface of a ceiling to retain the downlight in position, and an annular seating for the lamp socket having a collar dimensioned to protrude partially through the ceiling in which the downlight is to be mounted and a lower outwardly extending flange whose upper surface, in use, lies in contact with the underside of the ceiling, the cover comprising an open ended metallic sleeve having a layer or coating of an intumescent material on its internal and external surfaces and opposed openings through which locating arms of the downlight can pass, a lamp holder supported by a bracket above the sleeve and means for varying the height of the bracket above the sleeve.
The invention will now be described by way of example only with reference to the accompanying diagrammatic drawings, in which:-

Figure 1 is a side view of a downlight cover in accordance with the invention;
Figure 2 is a section taken along line A-A of Figure 1;and
Figure 3 is a side view of an alternative downlight cover in accordance with the invention.

The downlight cover illustrated in Figures 1 and 2 comprises an open ended metallic sleeve 1 formed in its side with two opposed openings 2. The internal wall of the sleeve has adhered to it a fibrous strip 3 of intumescent material and the external wall of the sleeve also has adhered to it a fibrous strip 4 of intumescent material. The strip 3 extends downwardly from the upper rim of the sleeve and is of a width of between a third and a half of the height of the sleeve. The strip 4 extends upwardly from the lower rim of the sleeve and is of a width which is also between one third and one half of the height of the sleeve. In an un-illustrated embodiment, one or both of the strips 3, 4 extend over the entire height of the sleeve. In this arrangement holes are formed in the strip to coincide with the openings 2. The openings 2 are therefore not masked by the strips.
The cover shown in Figure 3 is similar to that of Figures 1 and 2 except that the openings 2 extend downwardly to the lower rim of the sleeve thereby defining open ended slots.
A brass lamp holder 6 connectable to a source of electricity is supported by a bracket 7 above the upper open end of the sleeve 1. The lamp holder maybe of BC, ES, SES or SBC type. The bracket 7 has two downwardly extending arms 8 each formed with an open ended slot 9. Projecting from the sides of the sleeve are screws 11 whose shanks act as guides for the slotted arms 8 of the bracket. The screws can readily be tightened to lock the arms to the side of the sleeve at any one of several possible locations. Thus, the height of the bracket above the uppermost open end of the sleeve can be varied at will.
Because the lengths of conventional 35 and 50 watt lamps differ from 9, 11 and 15 watt energy saving lamps differ it has hitherto been necessary to have one size of sleeve to accept conventional lamps and another size of sleeve to accept energy saving lamps. With ventilated covers in accordance with this invention, one sleeve will accommodate all known lamps, whether these be of conventional or of energy saving type.
In use, the sleeve 1 slides over the downlight it is to protect with its internal wall defining a reasonably snug fit with the external surface of the downlight. The spring loaded locating arms of the downlight pass through the openings in the sleeve and the lower rim of the sleeve sits on or slightly above an annular projecting lip of a seating for the downlight. The assembly of the downlight and the sieve is then passed through a suitably sized hole formed in the ceiling until the projecting lip of the seating makes contact with the underside of the ceiling. The locating arms are then positioned to bear against the upper side of the ceiling to lock the downlight firmly in place.
The height of the bracket 7 above the sleeve 1 is then adjusted to accommodate the particular lamp used in the downlight and the lamp connected to the lamp holder.
In the event of a fire, the intumescent material rapidly exfoliates completely to seal the celling opening thereby preventing the passage of smoke and fire. The intumescent around the outer surface of the sleeve completely fills any space between the downlight and the ceiling, and the intumescent around the inner surface of the sleeve completely fills the void of the sleeve. Tests conducted show that fire and smoke protection for periods in excess of one hour are consistently achieved with covers in accordance with the invention.
In an un-illustrated embodiment, one or each sleeve surface is coated with a liquid coating of an intumescent material.
It will be appreciated that the foregoing is merely exemplary of fire covers in accordance with the invention and that modifications can readily be made thereto without departing from the true scope of the invention as set out in the appended claims.

Claims

An assembly of a downlight and a ventilated cover for resisting the passage of flames and smoke in the event of a fire, the downlight including a lamp holder connectable through a lamp socket to a source of electricity and at least two spring loaded arms which, in use, bear against the upper surface of a ceiling to retain the downlight in position, and an annular seating having a collar dimensioned to protrude partially through the ceiling in which the downlight is to be mounted and a lower outwardly extending flange whose upper surface, in use, lies in contact with the underside of the ceiling, the cover comprising an open ended metallic sleeve having a layer or coating of an intumescent material on its internal and external surfaces and opposed openings through which the locating arms of the downlight protrude, and a bracket positioned above the sleeve on which the lamp socket is mounted and from which the downlight is supported, and means for adjusting the height of the bracket above the metallic sleeve of the ventilated cover.
The assembly as claimed in claim 1 in which the sleeve is produced from steel.
The assembly as claimed in claim 1 or 2 wherein the sleeve is of constant diameter or cross section throughout its height.
An assembly as claimed in any one of the preceding claims wherein the intumescent material comprises fibrous strips or pieces of intumescent material adhered or otherwise fixed to the internal and external surfaces of the sleeve.
An assembly as claimed in claim 4 wherein the strips or pieces extend around or substantially around the entire internal and external circumferences of the sleeve to define rings of intumescent material.
An assembly as claimed in claim5 wherein the internal ring of intumescent extends from the uppermost rim of the sleeve to a position between one third and one half of the sleeve height.
An assembly as claimed in claims 5 and 6 wherein the external ring of intumescent extends from the lowermost rim of the sleeve to a position between one half and one third of the sleeve height.
An assembly as claimed in claim 7 wherein the openings extend to the lowermost rim of the sleeve to define open ended slots.
An assembly as claimed in claim 7 wherein the openings extend to the lowermost rim of the sleeve to define open ended slots.