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How-to · UK domestic

How to fit an outdoor LED bulkhead light

A bulkhead fitting is one of the most common outdoor lighting jobs: back plate on the wall, cable through the gland, three conductors connected, diffuser on. The job looks simple, and often is. The bits that catch people out are IP rating, the earth, and making sure the circuit already has proper RCD protection before anything goes outside.

Helpful video reference. The "4lite IP65 Wall Ceiling Light Installation Guide" from Screwfix covers the key steps clearly: back plate, gland, wiring and diffuser. The video is for a specific IP65 fitting but the wiring sequence applies to most standard UK bulkhead fittings. Watch it alongside this guide.

Before you start. This guide covers like-for-like replacement or a new fitting on an existing, correctly protected circuit. If you are running a brand-new cable from the consumer unit, outside to a new position, that is Part P notifiable work under Building Regulations. Stop and call an electrician. Also: confirm the circuit already has RCD protection before connecting anything outdoors. If in any doubt, switch off and call.

1. Check the IP rating for your location

IP stands for Ingress Protection. The two digits tell you how well the fitting resists solid particles (first digit) and water (second digit). For outdoor use in the UK:

Most modern LED bulkheads sold in the UK are rated IP65 as standard. Check the rating on the box before you buy. Fitting an IP20 indoor light outside is a common mistake that leads to water ingress, corrosion and an increased fire risk.

2. Choose your mounting position and cable route

Bulkhead lights are usually surface-mounted to a flat wall. The cable enters through a weatherproof cable gland built into the base. Position the fitting so the gland faces downward or at an angle where water will drain away, not pool inside.

If you are replacing an existing fitting, the cable will already be in place and the gland position is fixed. For a new position, confirm the cable route and how it exits through the wall before you start drilling. The cable itself should be twin and earth (1.0 mm² or 1.5 mm²) running in the wall in the standard prescribed zone where possible, or protected in conduit if surface-run.

3. Isolate the circuit at the consumer unit

Find the relevant lighting circuit on your consumer unit, switch it off, and test at the supply point with an approved voltage tester. A neon screwdriver is not acceptable for proving dead: use a two-pole tester with known working batteries, and test it on a known live source before and after using it.

If the fitting is outside and you are not certain which MCB or RCBO controls it, switch off all lighting circuits and test. Only restore one at a time until you identify the correct one.

4. Fix the back plate to the wall

Open the fitting, remove the diffuser and gear tray (if separate), and use the back plate to mark fixing positions. Most bulkheads need two or three screws depending on the design.

Drill and plug the wall with appropriate fixings for the surface: masonry rawlplugs and countersunk screws for brick or render, suitable fixings for UPVC cladding or timber. Feed the cable through the gland before you tighten the plate. Once the plate is on, tighten the cable gland until it grips the outer sheath firmly - this is the weatherproof seal, so do not leave it loose.

5. Connect the conductors

Most UK bulkhead fittings have a terminal block inside the body for three conductors:

If your cable is old pre-2004 wiring with red and black conductors, the red is live and black is neutral. The bare earth still needs green-yellow sleeving over it before it goes into the terminal.

Tighten each terminal firmly and tug each conductor to confirm it is seated. Loose terminals are the most common cause of faults in outdoor fittings.

6. Check the earth connection

Metal bulkhead fittings must have an earth connection at the fitting body. Most have a separate terminal on the casing as well as one on the terminal block. Connect the CPC to both if your fitting has them.

Plastic fittings with no metal parts accessible to touch do not need an earth at the fitting body, but the CPC should still be terminated correctly in the terminal block if the manufacturer specifies it.

If there is no earth wire in your existing supply cable, stop. An outdoor metal fitting with no earth is an electrocution risk. Call an electrician.

7. Fit the diffuser and test

Refit the gear tray and diffuser, making sure no wiring is trapped or pinched. Most bulkhead covers clip or screw on and have a rubber gasket that forms the IP seal - check the gasket is seated correctly in its groove before tightening.

Restore power at the consumer unit and test the light switch. Check for any unusual buzzing or flickering, which can indicate a loose connection or incompatibility between the LED driver and the switch (common with older dimmer switches on non-dimmable LED fittings).

Stop and call an electrician if: there is no earth wire in the supply cable; the existing cable shows signs of damage, discolouration or old rubber insulation; the RCB or MCB trips when you restore power; or the job involves running a new cable outside from the consumer unit, which is notifiable under Part P.

When to call us

Like-for-like bulkhead replacements are a straightforward job for a careful homeowner who is confident with the process above. New outdoor circuits, cable routes through walls, or anything involving old wiring without a proper earth - call. Small jobs in Sandwich are priced at £10 per 10 minutes.

Fitting outdoor lighting in Sandwich?

Richard fits outdoor bulkhead lights, PIR security lights and festoon supplies across Sandwich and east Kent.

Contact Richard

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