Garden Lighting Help Sheet No. 1 - Exterior & Ground Burial Transformers

A transformer is an electrical or electronic device which changes voltage; in garden lighting this is usually from mains voltage (240 volts a.c. - alternating current) to 12 volts a.c (low voltage). From the transformer to the garden lights low voltage cables typically run under mulch, gravel, paving, decking or over structures. To minimise cable voltage drop to the garden lights, identify groups of garden lights which can be supplied from one central transformer. Check that the transformer location is within the length of the low voltage cable permitted (see Help sheet 3: Low voltage cabling layout.) In many rear gardens, a typical garden lighting configuration may require one transformer on each side of the garden and perhaps one transformer to cover features at the far end of the garden.

The standard range of garden lighting transformers are housed in black weatherproof IP65 boxes to be mounted on a wall or post, hidden behind planting and landscape features, in manholes or outbuildings or under decking.

Part No.	Watts	Width mm	Height mm	Depth mm	Weight kg
B9505	50	121	106	78	1
B9510	100	121	120	78	2.3
B9515	150	134	141	88	3
B9520	200	134	141	88	3.3
B9530	300	134	141	88	4
B9540	400	172	155	110	6
B9560	600	172	175	110	8

Each unit has 600mm mains input and low voltage output cables for connection to steel wire-armoured mains cables and low voltage cables to individual garden light fittings in a separate weatherproof junction box, the size of which can be selected to suit the number of connections needed and to provide segregation of different voltages. Each transformer is resin-sealed in the case has a self-resetting thermal cut-off to protect against overload and is dimmable using an inductive dimmer suitable for transformed low voltage lighting.

Ground burial transformer kits, for locations where transformers can’t be hidden, comprise a polycarbonate enclosure to be drilled for the number and type of cable glands needed, a toroidal transformer and one or more two-part resin sealant packs. The transformer and cables are connected in the enclosure and operationally tested; the sealant pack is then mixed in its own sealed pouch & poured into the enclosure to completely seal it. The resin sets in about 30 minutes, after which the enclosure can be buried, with slab and warning tape over it. Each transformer has a self-resetting thermal cut-off to protect against overload and is dimmable using an inductive dimmer suitable for transformed low voltage lighting. Where several ground burial transformers are to be installed in an area, allow connection points with in-line fuses where possible above ground to allow for isolation in the event of future fault-finding. Connection of transformers to separate cores of a multi-core cable may also be considered. Surface-mounted transformers are preferable for ease of fault diagnosis and for extending or upgrading the system in the future.

Part No:	T9402	T9405	T9410	T9451	T9420	T9430
Watts	20	50	100	150	200	300

IP68 electronic transformers are adaptable units for ground burial, wall or post mounting or location under decking, hedges and shrubs. Each is a 150mm lozenge shaped sealed unit with 2m input cable for connection to a 240v supply in a separate weatherproof junction box and a 2m low voltage cable for connection to low voltage output cables to individual garden light fittings in a box or via heat shrink cable joint or cable splice kits. Not dimmable. Protection is by a non-resetting internal fuse.

B9401 35-105va 12v AC transformer
B9402 20-70va 12v AC transformer