I have outdoor lights around my screened in pool area. There is 1 wire that strings roughtly 50 feet, with 5 lights split off roughly 10 feet apart. When I purchased the house, the wire did not have a plug on it, and me not being an electrician, attempted to fix it. I found the lightbulbs for sale at One store only. It is a high voltage LED bulb, but very small and expensive. At 13$ each I bought one only. When attaching the new plug to the wire, I found no color coding on the wire to determine which was hot and neutral. I wired the neutral wire into the brass screw connector and vice versa for the other wire. I tested the bulb I bought with no luck except for an instant burnt out bulb. Upon researching, I found that writing on the wire casing indicates the neutral/white wire and re-wired the plug. Was that what burnt out my first bulb? Id hate to wate another $13 on a bulb when a new fixture will cost me $30.

Neutral is white wire, terminal (screw) is silver,
Hot is black wire, terminal (screw) is brass.

Verify voltage on bulb. AC has no polarity. With DC, only one way works.
Check for voltage on the wires with ground as the reference.
Neutral will usually have ribbs along the wire or an edge.
Have to feel or look very close.