Fire Door Monitoring Sensors: What They Prove, and What They Definitely Do Not

Last updated: 17 August 2026

Short answer: a door sensor cannot prove fire door compliance, and any supplier who says otherwise is selling you a problem. What it can do is tell you, continuously, that a fire door is being wedged open or has been tampered with between the statutory checks. The Milesight WS301 (£38.90 ex VAT) covers indoor communal doors; the IP67 EM300-MCS (£52.37) covers exposed or external openings.

That distinction is the whole point of this article. Regulation 10 requires a physical inspection by someone competent. A magnetic contact reports one bit of information, open or closed. Those are different jobs, and confusing them is how a building ends up with a dashboard full of green ticks and a set of fire doors nobody has actually examined.

On this page:

• What Regulation 10 actually requires
• What a sensor cannot tell you
• What a sensor genuinely does tell you
• WS301 or EM300-MCS?
• Where to put them, and how many
• Using the data as evidence
• Frequently asked questions

What Regulation 10 actually requires

Quarterly checks of communal fire doors, and annual checks of flat entrance doors on a best endeavours basis. The duty applies to multi-occupied residential buildings in England with storeys over 11 metres in height, and it has been in force since 23 January 2023.

The government’s fact sheet on fire doors under Regulation 10 sets out both duties: responsible persons must undertake quarterly checks of all fire doors including self-closing devices in the common parts, and annual checks of all flat entrance doors on a best endeavours basis, where best endeavours means determining the best approach to engage residents to gain access, and gathering evidence of the steps taken if access cannot be achieved.

There is a third duty that matters here more than most suppliers mention. Responsible persons must give residents information about the importance of keeping doors closed, that doors and self-closing devices are not tampered with, and that faults or damage should be raised immediately, at move-in and annually thereafter.

Read those three duties together and the role of a sensor becomes obvious. It has nothing to do with the quarterly inspection. It has everything to do with the two behaviours the resident-information duty is aimed at: doors left open, and self-closers tampered with.

What a sensor cannot tell you

A magnetic contact reports whether a door is closed. It says nothing about whether the door still works. That gap is much larger than it sounds.

A fire door inspection looks at the condition of the intumescent and smoke seals, the gaps around the leaf, the hinges and their fixings, the condition of any glazing and its beading, whether the door and frame are undamaged, whether the self-closer actually closes and latches the door from any angle, and whether the certification and specification are appropriate. Not one of those can be inferred from a contact sensor.

Worse, a door can be closed and still fail. A fire door with a defeated self-closer, a 6 mm gap at the head, or missing intumescent strip will read as perfectly closed to a magnetic contact all day long. If the sensor is treated as compliance monitoring, it will actively conceal that failure behind a green status.

So be precise in how the system is described internally. It is a door position and tamper monitor. It is not a fire door inspection, and it does not reduce the frequency or scope of the checks Regulation 10 requires.

What a sensor genuinely does tell you

It closes the gap between quarterly inspections with continuous evidence of misuse. A quarterly check is a snapshot four times a year. A contact sensor is a record every day in between, and misuse is a daily phenomenon.

The two findings that recur in real buildings are a fire door wedged open on a warm afternoon, and a bin store or riser door propped for convenience and forgotten. Both are exactly what a magnetic contact catches, and both are the behaviours the resident-information duty exists to address. Having a dated record that a specific door was held open for four hours on eleven occasions in a month turns a vague concern into something a housing officer can act on.

Tamper detection is the second genuinely useful output. The WS301 raises a tamper alarm when the device is dismounted, so removing the sensor is itself an event rather than a silent gap in the data.

The third use is a nudge. Where residents know that a propped fire door raises an alert to the concierge, the propping usually stops, and that behaviour change is worth more than the data.

WS301 or EM300-MCS?

Specifications are from Milesight’s published pages; prices are live UK stock ex VAT.

• WS301 — detection distance 10–15 mm, open/close status alarm plus tamper alarm on dismount, one 1200 mAh ER14250 cell giving roughly 4 to 7 years, IP20, −20°C to +60°C, 50.5 × 31 × 18.5 mm, screw or adhesive mounting. £38.90.
• EM300-MCS — detection distance 20–30 mm, IP67 with UV resistance, one 4000 mAh ER18505 cell with an 8000 mAh option and over 10 years quoted life, −30°C to +70°C, 105.6 × 85.3 × 27 mm, with integrated temperature and humidity sensing. £52.37.

For a communal corridor or a riser cupboard, the WS301 is the right device and the £13.47 saving per door adds up across a block. Its 10 to 15 mm detection distance suits a well-fitting door where sensor and magnet sit close together on the leaf and frame.

The EM300-MCS earns its premium in three situations: an external or partly exposed door where IP20 will not survive; a door with a larger or less consistent gap, where the 20 to 30 mm detection distance gives margin; and anywhere a battery change means arranging access, since over 10 years beats 4 to 7. Its temperature and humidity output is a useful secondary in an unheated bin store or plant room.

Where to put them, and how many

Start with the doors people actually prop, not with every fire door in the building. Monitoring all of them is expensive and generates noise; monitoring the wrong ones generates nothing.

The usual candidates are cross-corridor doors on residential floors, bin and refuse store doors, plant and riser cupboards, doors onto smoking areas or bike stores, and stair lobby doors near entrances. Those are where convenience conflicts with fire strategy, and they are where the propping happens.

Mounting matters more than it looks. The sensor goes on the door frame and the magnet on the leaf, or vice versa, with the gap between them inside the detection distance when the door is closed. On a door with a rebate or an intumescent seal, that gap is not always where you expect, so check it with the door shut before committing to adhesive. Never fix anything into the leaf or frame in a way that compromises the door’s certification, which is a question for the responsible person, not the installer.

Each sensor reports over LoRaWAN, so a single gateway usually covers a block and no cabling is needed at the door. Our gateway buyer’s guide and LoRaWAN primer cover that side, and the Awaab’s Law phase 2 guide covers a related monitoring duty in social housing.

Using the data as evidence

Records are a Regulation 10 theme, and this is where the data earns its keep. Responsible persons are expected to keep records of completed and failed inspections and to ensure faults are identified and rectified. Door-position data does not replace those records, but it sits alongside them well.

Set a threshold rather than alerting on every opening. A fire door opens hundreds of times a day in normal use and none of that is interesting. Held open beyond a few minutes is interesting. Held open repeatedly at the same time each day is more interesting still, because it points at a cause: a delivery round, a bin collection, a smoking break.

Then close the loop. Log what was done about each alert, and keep that with your fire safety records. A dated trail showing a propping problem identified, residents informed, and the pattern stopping is exactly the kind of evidence that demonstrates active management of the building.

Finally, review it against the quarterly inspection. If the inspection finds a self-closer that has been disconnected and the sensor data shows that door standing open for weeks beforehand, you have learned something about that location that neither source would have told you alone.

Frequently asked questions

Can a sensor replace a fire door inspection?

No. Regulation 10 requires physical checks of the door, its seals, gaps, hinges, glazing and self-closing device. A magnetic contact reports open or closed and nothing about condition. Use it between inspections, never instead of them.

How often must fire doors be checked?

In multi-occupied residential buildings in England with storeys over 11 metres, communal fire doors must be checked quarterly and flat entrance doors annually on a best endeavours basis, under the Fire Safety (England) Regulations 2022, in force since 23 January 2023.

Which sensor suits an external fire door?

The EM300-MCS, because it is IP67 with UV resistance and rated −30°C to +70°C. The WS301 is IP20 and belongs indoors.

Will fitting a sensor affect the door’s certification?

Anything fixed to a fire door leaf or frame is a matter for the responsible person and the door’s certification, particularly if screws penetrate the leaf. Adhesive mounting avoids penetration but must be assessed for the environment. Get this signed off before installation, not after.

How long do the batteries last?

The WS301 is quoted at roughly 4 to 7 years on a 1200 mAh cell depending on configuration. The EM300-MCS is quoted at over 10 years on a 4000 mAh cell, with an 8000 mAh option. Where access is difficult, that difference matters more than the £13.47 price gap.

Should every fire door be monitored?

Rarely worth it. Monitor the doors that get propped: bin stores, riser cupboards, cross-corridor doors and anything onto a smoking or bike area. Whole-building coverage costs a great deal and mostly records normal use.

The bottom line

Be honest about what you are buying. A contact sensor is a misuse and tamper monitor that fills the gap between quarterly inspections, and described that way it is genuinely useful and cheap at £38.90 a door. Described as compliance monitoring it is a risk, because a defeated self-closer reads as closed. Pick the handful of doors that actually get propped, set a hold-open threshold rather than alerting on every swing, and keep the record alongside your Regulation 10 inspections. Prices above are live UK stock ex VAT — browse the range, or send us a door schedule and we will spec it and quote within one working day.