Do I need wireless sensors to comply with food hygiene law?

No. Retained Regulation (EC) 852/2004 requires effective monitoring at critical control points and records commensurate with the nature and size of the business. It does not specify an instrument. A calibrated probe and a written diary meet the requirement; sensors change the labour and the completeness of the record, not the legal duty.

What is the difference between a Bluetooth probe and a wireless sensor?

A Bluetooth probe still needs a person to take the reading; it just removes the typing and the transcription error. A wireless sensor is fitted to the equipment and records continuously without anyone present, usually with alerting when a temperature drifts out of range. Several suppliers offer both, and the sensors are the part that carries a hardware cost.

Guide

Digital temperature monitoring and probe integration

Updated 2026-08-15

Temperature is the check most food businesses record most often, so it is the one automation pays back on first. It is also where the hardware bill hides.

Three different things get called temperature monitoring

Manual logging in an app
Bluetooth probe capture
Continuous wireless sensors

What the law asks for, and what it does not

It does not ask for sensors. Retained Regulation (EC) 852/2004, Article 5 requires effective monitoring at critical control points and "documents and records commensurate with the nature and size of the food business". Annex II asks premises to provide temperature-controlled storage "designed to allow those temperatures to be monitored and, where necessary, recorded". A calibrated probe and a paper diary satisfy that. What automation changes is the labour and the gaps, not the legal position.

The numbers your system should alert against

8 °C chilled. gov.uk states that chilled food must be kept at 8 °C or below and that this is a legal requirement in England, Wales and Northern Ireland, and recommended in Scotland (gov.uk).
5 °C fridge setting. gov.uk advises setting the fridge to 5 °C or below so food stays cold enough even when the temperature moves. Alerting at 8 °C leaves you no headroom.
63 °C hot holding. Schedule 4 of the Food Safety and Hygiene (England) Regulations 2013 makes it an offence to hold cooked food for service or display below 63 °C where that is needed to control pathogens.
82 °C on reheat, in Scotland only. Schedule 4 of the Food Hygiene (Scotland) Regulations 2006 requires reheated food to reach at least 82 °C. If you operate across the border, check the system lets you set different limits by site.

What to ask before you buy hardware

What does each monitored unit cost, and how many gateways or controllers does my site need?
Is installation included, and who is responsible if a probe is fitted badly?
How is calibration handled, how often, and what does it cost after year one?
What happens to the data when the internet drops: does the sensor buffer readings, or is the record lost?
Who receives an out-of-hours alert, and what happens if nobody acknowledges it?
Can I still record a manual probe reading in the same system when a sensor is being serviced?

The buffering question is the one that separates a monitoring system from an expensive thermometer. A gap in an automated record is harder to explain than a gap in a paper one, because nobody was there to write anything down.

Corrective actions matter more than readings

Article 5(2)(e) of retained 852/2004 requires "establishing corrective actions when monitoring indicates that a critical control point is not under control". A system that captures thousands of in-range readings and nothing about the morning the walk-in failed is the weaker document. Ask to see what the record looks like on a day something went wrong, not on a day everything was fine.