12v LED garden lighting upgrade – add second switchable circuit on same or separate driver?
First a little background, my old iron 12V mains transformer has died but I have a couple of stainless garden light fittings I want to retain which will take MR16 bulbs in the GU5.3 fittings. I want to add a couple more lamps to that circuit for a total of 4x 7W in series. In addition to that, I want to run another 12V circuit off the same mains supply to add lighting to a shed with two additional 7W MR16s but include a 2-pole switch in that circuit so I can power them on from the shed only when I need them (the mains switch will of course control both the garden and shed circuit).
The garden loop is about 50-65 feet using 2-core 12AWG wire so the estimated voltage drop looks negligible. My main question is whether to run both circuits off a single constant voltage LED driver or wire two separate constant voltage LED drivers off of the mains circuit (240V 10A). Obviously one driver will lower the up-front cost but will switching the shed circuit create any safety or inefficiency issues?
I couldn't find any clear info on mains current draw for LED drivers, only conventional transformers but I assume it's negligible. For current draw on the 12V circuit I estimate:
28W (4x 7) / 12 = 2.33A
14W (2x 7) / 12 = 1.16A
Total peak draw: 5.5A
If using two drivers I have selected a 20W driver that is rated for up to 1.67A and a 30W driver rated for 3-30W output (couldn't find current ratings) – both are rated for garden lighting in IP65 enclosures.
If using one driver I'll try and find a 50W driver rated for around 8A max draw. Not too worried if they're adjustable drivers given the minimal estimated voltage drop (2%).
- Single or two drivers (efficiency, bulb life, safety considerations)
- Is it ok to wire two drivers in parallel off a 10A 240V mains circuit if total draw under 10A?
- Anything else I'm missing?
Submitted May 28, 2021 at 10:41PM by Archie_Pelego
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