wire low voltage lights to one cheap tap

[electroshak3]

Low voltage newbie here! I've got a cheap 300W transformer (the standard Home Depot type) that only has one set of terminals, but I need to run 2 or 3 separate 12 AWG cables out to my lights (about 15 lights / 120W total over 150 feet).

Can I just splice all those separate runs together underground and run one single cable up to the cheap transformer terminal?
Or is that a terrible idea? Should I just bite the bullet and buy the multi tap transformer to help manage voltage drop on those longer runs? Help me avoid a wiring mess!

 

[ZenithDragon]

You can splice them, but it’s not ideal. Each long run will drop voltage differently, so you’ll end up with uneven brightness. Multi-tap transformer’s the cleaner, safer move long-term.

 

[PGB1]

If those 15 lamps use 120 watts are LED, those will be some mighty bright lights.
Although LED conversions to incandescent equivalent is properly done with lumens instead of watts, average your lamps will be like having 60-75 watt incandescent each. Will your neighbors complain?

What ZenithDragon wrote about a multi-tap is a good plan. (Or single transformers for each circuit.)

Another option might to pick up a small solar panel which charges a battery for the lights. (You did not mention if AC or DC, so if AC you will need an inverter type.) I've noticed them in stores like Costco and Lowes.

 

[MamaEVA]

I’d probably go for the multi-tap just for peace of mind. The cheap transformer’s fine for short runs, but once you start mixing lengths, it sounds like things get messy fast.

 

[Alan]

Splicing multiple home-run cables underground will work, but it becomes messy fast and harder to troubleshoot later. The bigger issue is control. Multi-tap transformers exist exactly for situations like yours so you can balance out long and short runs. Do you have any flexibility in where the transformer sits, or is the 150-foot distance locked in?

 

[PGB1]

If the low voltage wire is small enough gauge, perhaps UR or UY connectors would be useful. They are silicone filled and can live out in the weather, perhaps next to the transformer. (I've no idea if they can be buried.)