How do you wire outdoor wall lights from inside the house?

Drill a 10–12mm hole through the wall behind the switch position, angled slightly downward to the outside so water cannot track back in. Pass the 1.5mm² three-core-and-earth cable through in a rubber grommet or flexible sleeving, then terminate it in the weatherproof backbox or terminal enclosure supplied with the fitting. The live feed goes to the indoor switch first, and the switched line continues through the wall to the light — never place a joint outside unless the enclosure is rated IP65 or better. Most outdoor wall lights, including the Terba curved-arm and Cipher caged fittings, accept 1.5mm² cable directly through a glanded entry on the backplate, which keeps the seal intact. When choosing the fitting itself, match the backplate to the wall material: brick and render take standard fixings, while timber-clad walls need a mounting plate with a drainage gap behind it. The same method applies across the full range of outdoor wall lights, so the wiring plan rarely changes from one fitting to the next. Always isolate the circuit at the consumer unit before drilling or terminating anything.

IP44 is the minimum rating for any outdoor wall light exposed to rain splash, and IP54 or IP65 is the sensible choice for open elevations facing prevailing weather. The first digit covers solid objects, the second covers moisture, so an IP44 fitting resists water splashed from any direction — adequate for a porch under cover, but marginal for a gable wall with no eaves. BS 7671 adds zoning rules where the outside wall borders a bathroom containing a bath or shower: a fitting mounted on that wall within the zone 2 volume must meet the same IP and 30mA RCD requirements as an interior bathroom luminaire. In practice this rarely affects garden walls, but it catches out self-builders wiring en-suite external lighting. Check the manufacturer's declared rating on the backplate rather than assuming — a fitting sold as suitable for outdoor use may still be IP43, which fails on exposed walls. Mount the light at 1.8–2.0 metres to the centre of the backplate, seal the cable entry with the supplied gland, and apply a bead of exterior-grade silicone around the top edge of the backplate only, leaving the bottom edge open as a drainage path.

A standard single-gang indoor switch on the live side of the supply is the simplest arrangement and complies fully, provided the circuit is RCD-protected. The alternative is to omit the through-wall switching cable entirely: fit a weatherproof switch next to the door outside, or use a PIR sensor head that switches the load directly. PIR control suits security and porch lighting because the lamp only runs when movement is detected, which cuts running hours substantially — a meaningful saving on LED fittings left on overnight, and one of the practical steps in future-proofing your home against energy bills. If you use a PIR, set the time delay to 1–2 minutes and the lux threshold so it ignores passing traffic but triggers at the door. Manual override is worth having: many PIR wall lights switch to constant-on if you toggle the indoor switch twice within two seconds, which is useful for maintenance or entertaining. Avoid dimmer switches on outdoor fittings unless the manufacturer explicitly states compatibility, because cold temperatures and sealed enclosures change the load characteristics and cause flicker on low settings.

BS 7671 requires a 30mA RCD for any circuit serving equipment outside the equipotential zone, which covers every outdoor wall light without exception. In a modern consumer unit this means taking the supply from an RCBO or an RCD-protected way on the board; in older installations with a split-load board, confirm the lighting way is actually on the RCD side before connecting anything, because some legacy boards leave lighting ways unprotected. If the existing indoor lighting circuit is not RCD-protected, run a dedicated radial from a new RCBO rather than spurring off an unprotected way — it costs little more and isolates outdoor faults from the house circuits. Work on fixed wiring in England and Wales falls under Part P of the Building Regulations: notifiable if you install a new circuit, self-certifiable if you are simply replacing like-for-like on an existing protected circuit. Tenants should not attempt this work themselves; repair obligations for fixed electrical installations sit with the landlord, as set out in Citizens Advice: landlord repair responsibilities. Test the RCD with its integral button after completing the installation, and record the result on any electrical certificate issued.