I need to move an existing cable for a bathroom vanity. The existing light is a strip light so the cable comes through the middle of the wall to the middle of the fixture. The new light will be 18" to the right of the current location but the cable isn't long enough to be re-routed. Is there a secure method to join/extend the cable and then drywall over the top?

Working on a tight budget so I won't be able to rewire the exiting loop or cable to add the length.

Any help or advice is appreciated.

First of all, it is code violation to cover over a connection point.

If you join the wires together, you must use a junction box and cover. The box cannot be covered over by drywall. It has to be easily accessible.

Only this connector is allowed. However, it may be disallowed in your area.

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