Thorn Lighting invented the 2D lamp in 1983 and since then it has become a workhorse of circulation area lighting. Drive past any local authority tower block at night and you’ll see rows of wall-mounted bulkhead luminaires with the tell-tale cool white glare of 2D lamps.
It’s easy to see why the 2D bulkhead was successful: it’s cheap, reliable and has a good distribution of fluorescent light in a pleasing circular package.
But its ubiquity means it was only a matter a time before an LED retrofit was developed. There have been a few, but the Zd from British company Zeta Controls is the first we should take seriously. Zeta is the brainchild of Oxford engineering graduates Paul Tyrrell and Phil Shadbolt, who developed the Zd unit.
Using patented technology, the Zeta team says it has created a product that eliminates point source glare and solves the heating issues associated with LED lighting in an IP-rated housing. It’s available both as a lamp and as a lamp-and-luminaire combination.
The main benefit of the Zd over the 2D is, of course, lower maintenance costs. But lower energy consumption is available too: a triac dimming option with microwave sensing allows, says the company, eight-fold efficiency gains by operating the unit only when it is needed.
Our tests reveal the 23W Zd delivers 1,300 lumens at an efficacy of 57 lumens per watt. But what is really remarkable is that the Zd doesn’t need a heatsink, so no need for a chunky die-cast body. It will happily sit in an adapted 2D luminaire.
HOW WE DID THE TESTS
The benchtest took place at Lux’s official test house, the highly respected laboratories of 42 Partners in Wolverhampton. The tests were conducted in a 3.5 metre integrating sphere (one of the largest in the UK) in accordance with EN13032 at 25ºC with the luminaire in a horizontal orientation after 100 hours burn-in.