Feature, Residential

Why LEDs struggle to break into prisons

The UK's Ministry of Justice has unveiled its latest technical specification for lighting – but it barely mentions LEDs.

Looking to win some business from the custodial sector? The Ministry of Justice has unveiled its latest technical specification for lighting, with the emphasis firmly on quality and longevity. 

However the document – titled the Ministry of Justice, Estate Directorate Technical Standards: Electrical Installation (operating at low voltage and extra low voltage): Standard number: STD/E/SPEC/018 – is remarkably short on LEDs.

After all, there are lots of aspects of LED performance that would appear to lend themselves to custodial lighting: the discreet form factor that the source makes possible that could reduce overall luminaire size; the operational benefits from energy usage and lighting control; the potential safety benefits in using Power over Ethernet wiring; and the colour quality that’s now available across the LED range are just four of the headline issues pointing towards the potential for LED lighting. 

But there are some serious technical criteria to overcome first.

Manufacturing standards

As you’d expect, all of the usual luminaire and components manufacturing and testing standards need to be complied with – and if your equipment doesn’t comply with BS EN standards, then you’ll have to make a special submission to MoJ Technical Standards for its consideration.

Luminaire testing

The testing that you do won’t be done in-house, I’m afraid. Luminaires will be tested either by MoJ or, more likely, you will engage a UKAS-accredited test house that will carry out tests in accordance with the MoJ Model Agreement for testing.

Sturdiness of construction

Ingress and impact rating will apply. The MoJ is looking for impact resistance of IK10 and an IP2X for general use inside buildings. And luminaires will be fitted with tamper-resistant exposed fixings. And you will comply with all anti-ligature design requirements.

Of course, if you’re looking to provide luminaires for cells, you’ll have to work much harder. The specification for cell luminaires requires an IP65 rating because fires inside cells are dealt with by ‘cell inundation’, achieved by spraying water into the cell via an aperture in the door. And the IK rating is off the scale. After all, these are places where the occupants don’t necessarily want to be and occasionally decide to take out their frustrations on whatever is to hand.

Luminaires need to withstand sustained attack without distortion that might lead to supports for ligatures. And for the same reason, burn tests are also carried out on diffusers to check if it’s possible to male a hole that could be used to support a hook for a ligature.   

LED performance reporting

LED technology has been reviewed on a regular basis and has yet to gain a foothold in the sector. This may have something to do with the current requirements for lamp and luminaire performance which marginalises the usual in terms of cost savings benefits.

Required life terms

Light source mortality must be no greater than 10% within the declared life expectancy.
Light source output must not fall lower than 80% at the end of declared life expectancy.
Fluorescent tubes are required to have a declared life expectancy of 45,000 hours, with associated HF control gear having a life expectancy of at least 50,000 hours.

There’s an important point to make here. These figures relate to sources and control gear, not to entire luminaires. Embedded LED fixtures that require removal of the entire fixture are likely to be frowned on. Informally, the MoJ would expect a life term of around 25 years for luminaire housings; not an unreasonable figure when so much effort has to go into the construction quality.

What’s evident from reading the MoJ standards for prison lighting is the emphasis on luminaire performance. Light sources are selected because of their known qualities, and T5 lamps with 3000K colour temperature could be described as the default lamp, given the performance standards demanded. At some point the LED will start to make an appearance, probably within an existing, approved, luminaire housing. Whether that basic kind of retro-fit delivers all of the benefits that LED technology can bring to custodial lighting is a question still to be answered – possibly yet to be asked.


  • Lux Review, in association with Designplan,  is hosting a special webinar discussing Best Practice in Lighting for Prisons, the hows and the whys of a custodial lighting specification. 


  • The webinar takes place on Wednesday 8 June at 1pm BST and is free if you register here. Please click on the Lux Webinar logo for more information and registration details


Picture: Nino Photography