Grade D LD2 or Grade A? Choosing the Right Fire Alarm for Your HMO

Two letters, two different questions

BS 5839-6 describes a domestic fire alarm system with two labels. The grade (A, C, D1, D2, F1, F2) describes the type of equipment and how it is powered. The category (LD1, LD2, LD3) describes how much of the property is covered. A licensing officer asking for 'Grade D LD2' is therefore asking for a particular kind of alarm installed in a particular set of rooms.

The grades, from simplest to most complex

• Grade F: battery-only alarms. F1 has a sealed long-life battery, F2 a replaceable one. Acceptable in some owner-occupied homes, not in licensed HMOs.
• Grade D: mains-powered alarms with a backup battery, interlinked so they all sound together. D1 has a sealed, tamper-proof backup battery; D2 has a replaceable one. Grade D1 is what most new HMO installations use, and it is the system that costs from £600 installed.
• Grade C: mains-powered detectors and sounders with central control and a standby supply, but without a full panel. Rarely specified for HMOs today.
• Grade A: a full fire alarm system with a control panel, detectors, manual call points and sounders, installed to the commercial standard BS 5839-1 for its components. Required for larger HMOs and quoted from around £1,200.

The categories, from most to least coverage

• LD1: detection in every circulation space and every room where a fire could start, apart from bathrooms and small cupboards. The most protective and the most expensive.
• LD2: detection in the escape routes plus the rooms with the highest fire risk, in practice the living rooms and kitchen. This is the category most London councils ask for in shared houses.
• LD3: detection in the escape routes only. The minimum for a single-family house and generally not enough for a licensed HMO.

Which one does your HMO need?

The decision belongs to your council's licence conditions and the property's fire risk assessment. Most London boroughs base their conditions on the LACORS housing fire safety guidance, which broadly works like this for shared houses:

• One or two storeys: Grade D, usually Category LD2 in London because most boroughs want living rooms covered as well as the escape route.
• Three or four storeys: Grade D, Category LD2, often with emergency lighting on the escape route.
• Five or six storeys, or buildings with complex layouts or higher risk: Grade A, Category LD2, with emergency lighting.
• Converted buildings with self-contained flats: often a mixed system, with a Grade A system in the common parts and Grade D alarms inside each flat.

Wired or radio-interlinked?

Grade D alarms can be interlinked by cable or by radio. Both meet the standard. Wired interlinks suit empty properties or refurbishments where cable can be run neatly. Radio-interlinked alarms suit occupied, furnished houses because there is no cabling between alarms, so nothing to chase into walls or run under floors. The mains supply to each alarm is still required in both cases.

What each option costs

• Grade D1 LD2 for a typical shared house: from £600 installed and certificated.
• Grade A panel system: from around £1,200, depending on the number of zones and devices.
• Annual servicing for either: from £80 per property, with a certificate issued every visit.
• Emergency lighting and extinguishers: quoted per property at the survey.

Getting it right first time

Ask the installer to state the grade and category on the quote and on the certificate, and to confirm it matches your licence conditions. Security Red Alert surveys every HMO before quoting, installs Grade D and Grade A systems to BS 5839-6, and issues the certificate on the day. Call 020 8946 5567 for a free survey anywhere in London.