Technical
Bulletin
Painting of Fire-Resistant Cables
Painting of Fire-Resistant Cables
Frequently asked questions
1. If the cabling for a fire detection and fire alarm system has been painted, should a variation to BS
5839-1 be agreed and recorded?
2. Will the paint have any effect on the integrity of the cable.
The Facts
BS 5839-1 provides guidance for designing, installing, commissioning, and maintaining fire detection & fire
alarm systems in a non-domestic setting and recommends the use of either Standard or Enhanced grade
cabling for FD&A systems.
The Code of Practice recommends all cables used for fire detection & fire alarm systems should be of a single
common colour, and states that red is the preferred colour. Although this does not preclude the use of other
colours. The colour of the cable used for FD&A systems should not be used for cables of other general electrical
services within a building, in order for them to be clearly distinguishable from those of other circuits.
Painting of Cables
Most grades of Standard or Enhanced fire-resistant cable comprise of a Low smoke zero halogen (LSOH)
sheath.
In general, water-based paints are suitable for use on LSOH cables.
Oil/organic solvent-based paints might be likely to cause a swelling and softening to the cable following shortterm exposure, with potentially more serious impact on the cable integrity by way of degradation such as
cracking in the long term. The application of such Oil/Organic solvent-based paints would likely therefore not
be recommended by cable manufacturers1.
Furthermore, a significant concern associated with painting LSOH-sheathed cables is the potential impact on
their low smoke and/or zero halogen attributes during a fire incident. Any paint containing chlorine
compounds will augment the production of halogen gas emitted by the cable in a fire scenario. Additionally,
the low smoke properties of the cable sheath might be compromised in areas where paint is applied, as the
paint tends to generate significantly more smoke when burned compared to the cable itself.
It's important to note that once a cable is painted, its condition differs from when it underwent testing
according to BS 502002. Due to the applied paint, a manufacturer1 will be unable to guarantee the long-term
fire resistance of the cable, irrespective of whether the paint has any material reaction with the cable sheath
for either a short- or long-term duration.
Caution should also be taken where intumescent paints are used on or around cables. Whilst these types of
paints should provide an improved fire performance over standard paints, the underlying principle remains:
the cable hasn't undergone specific testing, making it impossible for manufacturers to assure its fire
resistance even with the use of such paints.
1
2
Prysmian UK
BriBsh Standard for Method of test for resistance to fire of unprotected small cables for use in emergency circuits
Painting of Fire-Resistant Cables • Version 1 • December 2023 •
Tel: +44 (0)20 3166 5002 • www.fia.uk.com
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Painting of Fire-Resistant Cables
In some instances, it might be appropriate to use PVC sheathed cables in an FD&A system or associated
systems.
Using a water-based paint typically poses no threat to the integrity of a PVC-sheathed cable. However, the
scenario differs for an oil-based paint. If solvents are part of the composition of a water-based paint, they
tend to evaporate rapidly, leading to very brief contact with the cable. As per the FIA consultation with cable
manufacturers, no long-term detrimental effects were foreseen in this regard.
Solvents present in oil-based paints tend to expedite the leaching of plasticisers within the PVC cable sheath.
This can result in reduced mechanical strength, raising the likelihood of cracking, brittleness, and decreased
cable flexibility. The presence of solvents or chemicals within oil-based paint could amplify the generation of
smoke, acid gas, and flame propagation tendencies of PVC cables.
Conclusion
Where cables are clipped directly, and therefore exposed, it is possible that at some point during the lifetime
of the system, the cables will be painted when a building is decorated.
Whilst this would visually alter the colour of the cable, it has not physically changed the original cable colour,
and as such, a variation to the recommendation in BS 5839-1 would not need to be proposed.
It would be good practice for any servicing and maintenance organisation to reference that the cables have
been painted, as part of their Special Inspection / Takeover documentation and on any subsequent service
documentation. However, this notation alone doesn't necessarily imply the need for cable replacement.
Where the original cable sheath markings such as manufacturer, grade of cable, conductor size, voltage rating
and 3rd party approval are likely to have been obscured due to the paint, it might be prudent to consider the
installation of labelling or identification markers to the cabling, therefore ensuring it remains identifiable as
FD&A cabling.
The FIA extends gratitude to Prysmian UK for providing valuable information used in creating this technical bulletin. For
further support and details regarding their products, comprehensive information is available in the technical section of
their website. https://uk.prysmiangroup.com/technical-area
Painting of Fire-Resistant Cables • Version 1 • December 2023 •
Tel: +44 (0)20 3166 5002 • www.fia.uk.com
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