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Ground burial transformer, Black, 12 v ac, 20va, IP68

The T2504 ground burial 12v weatherproof wire-wound toroidal transformer is resin-potted into a black polycarbonate boxes. Each transformer has a self-resetting thermal cut-off to protect against overload, 1.2m mains input cable and 1.2m 12v output cable for connection using separate weatherproof junction boxes (cable & connections carrying different voltages must be segregated) suitable for ground burial.

Dimensions 145mm depth, 150mm width.

The primary input cable HO5RN-F marked PRI takes the 240v feed and the secondary black cable SEC takes the 12v feed to the fitting or LV cabling.

Low voltage transformer loading example

The majority of exterior waterproof low voltage transformers are wire wound ( magnetic) torodial which are sealed in hard resin to prevent water ingress. The transformer must be loaded to 70% of it maximum capacity for it to function correctly. If you are going to put LED lamps on the transformer we recommend loading it to 80% of its maximum load capacity.

Transformer location and low voltage cabling

1.     Try and keep cable runs from transformers to garden light fittings as short as possible to ensure optimum performance, no
         more than two metres to the first lamp.

2.     Locate a transformer centrally amongst a group of garden lights it is to power; e.g. a radius of 8 metres for 5w LED lamps

3.     If you decide to run 2 sets of garden lights operated by separate switches, you must provide 2 separate transformers & circuits.

4.     Try not to put more than 10 lights on any one transformer otherwise voltage drop can reduce lamp and transformer performance.

5.     Try to avoid putting cable runs straight through the middle of the garden and try to run them along the fence line first, this will
        reduce the risk of putting a spade or fork through them when gardening.

6.     Where possible always try to keep the transformer above ground mounted on a fence post or spike, if you do have to bury them  make sure you use the burial    kits and fill with resin to reduce water ingress.


Make all connections in T9969 underground joint kit or similar resin-sealed joint. (Boxes with silicon-sealed lids do not protect against ingress of moisture through condensation and capillary action: ordinary silicon sealant does not bond reliably with all enclosure materials.) After burying the transformer and associated junction boxes, lay a paving slab or similar protective material over it, cover with cable warning tape and back-fill hole. NB: Where multiple ground burial transformers are to be installed in an area, allow connection points where possible above ground to allow for isolation in the event of future fault-finding. Connection of transformers to separate cores of a multicore cable may also be considered. Failure to adopt these recommendations may mean difficulty in fault diagnosis in the future and in extending or upgrading the system.

Item Specifications

IP rating: IP 68
Dimensions: Dimensions 115mm depth, 150mm width
watts: 20 Watt, 150 Watt, 50 Watt, 100 Watt, 200 Watt