P1 and P2 fire alarm categories
P1 and P2 are property-protection categories under BS 5839-1. They concern protection of property, assets or continuity rather than being interchangeable with life-safety L categories.
Reviewed: 20 August 2026
This guidance is general information. The correct fire safety measures depend on the premises, its use, occupants, fire risk assessment and applicable legal duties.
P1
P1 is the broader property-protection category, using automatic detection across the premises subject to the detailed recommendations and documented variations.
P2
P2 provides automatic detection in defined areas where the fire risk or consequences justify property protection.
Life and property objectives can coexist
A system can have both life-safety and property-protection objectives. Design documentation should make the intended categories clear.
Business continuity
Insurer requirements, critical operations or high-value assets can influence property-protection objectives, but do not replace separate life-safety duties.
Frequently asked questions
What is the difference between P1 and L1?
P1 is a property-protection category; L1 is a life-safety category.
Can one system have both L and P categories?
Yes, where it is designed and documented to satisfy both objectives.
Sources and further reading
For legal duties and technical standards, use the current primary source and professional advice where required.