Each harness is 30 metres (100ft) long with 100 lights. These have a clip at the end with 10 metres worth of lead that you simply plug into your transformer that is provided. Once you have completed this all you have to dd is plug your waterproof transformer into the mains and you are away. Simple as that. Each harness has to run to the transformer they cannot be joined together. Technical jargain - The lamps are long life, 10,000 hrs each 30m harness requires 30 watts (1.5 amp) of power 0.15amp of mains. Spare bulbs are availablle code B1's 24v 0.29w and are available at £25.00 for 100. We can also provide these Lights in Blue, Red, and green but this is subject to a surcharge of £100.00 due to little elves changing the bulbs over for you.