There are numerous ways to run the cabling or wiring from the roof back down to engine bay and listed below in order of preference is how most professionals, be it, 4x4 shops or auto electricians will complete the install.
Running wiring from the roof is generally not a plug and play affair and will require some auto electrical knowledge in selecting suitable wiring gauge and the joining or termination of wires due to the extended length of wiring required in addition to the supplied wiring harness.
1. Down the side of the windscreen glass. This is entirely vehicle dependent as some vehicles windscreens do not allow this position whatsoever. Generally wiring is run from the light into some twin core heavy gauge wiring available from any 12v supplier. This wiring will be positioned in the side of the windscreen and held in with some suitable silicon adhesive.
2. Down the back of the cab. The wiring will be much longer in lineal metres and less discreet, however is an applicable option and generally only needs cable ties to install. The cabling is run along the length of the roof attached to the roof rack or rail, and in the case of a ute, will generally loop across to either the sports bar or headboard of the tray itself and head down to the chassis rail then off to the engine bay.
3. Down the snorkel. Although not commonly adopted, it is possible to loop the wire from a roof light bar into the back of the snorkel head. Once it is in the snorkel head, the cable will run down into the dirty side of the airbox and will require drilling through the side of the airbox to penetrate the wiring back into the engine bay. (note; the penetration through the airbox will need to be completely sealed and tested prior to any possible river crossing)
4. Drilling through the roof. This is the least favorable option as it is not reversible. This option is quite self explanatory, where a hole is simply drilled through the outer roof skin and wires passed through a rubber grommet into the roof cavity and fed down into the vehicle.
Please refer to these above options as a guide only. It is always best to consult a 4x4 shop or qualified auto electrician on the intricacies of the install process and the correct selection of correct wire gauge if you are not quite sure.
Unfortunately we do not complete any installs.