Lighting & Electrical
An enclosed trailer needs the same exterior lighting as any other trailer — plus, often, interior electrical the open trailer types don't.
Exterior Lighting
Tail lights, brake lights, indicators, number plate light and reflectors — the same baseline requirement as any trailer type, wired via 7-pin (unbraked/mechanically braked) or 12-pin (electric brakes) plug matching the tow vehicle.
Interior Power
Trailers set up as a mobile workshop or secure equipment store often add interior lighting and 12V or mains power points — genuinely useful, but this is auxiliary electrical work separate from the trailer's road-legal lighting circuit, and should be wired as such rather than tapped off the tow vehicle's trailer plug, which isn't rated for that load.
Questions & Answers
Can I run interior lighting off the same plug as the trailer's road lights?
Not advisable — the tow vehicle's trailer plug is rated for lighting/brake circuits, not auxiliary interior power. Interior lighting or power points should run off a separate deep-cycle battery/solar setup rather than the road-lighting circuit.