Collingwood JB4 (Series) Gel Filled Waterproof Junction Box

A Sealed Joint for Outdoor Lighting Runs

The JB4 is a gel filled junction box built for joining outdoor series wired lighting, the kind of job you get when a run of bollards or ground lights needs to be linked together underground. It gives you a proper sealed connection between two cables without a bulky above ground box getting in the way.

Black Plastic, Built to Be Buried

The casing is plastic, moulded in black, and small enough to bury or tuck out of sight. At roughly 93.5mm long and 36mm wide, and weighing just 0.1kg, it sits easily alongside the cable run rather than becoming its own feature in the garden.

How It Works

Inside the JB4 is a single terminal block packed in gel. When you close the box, the gel surrounds the connection and seals it against water. Because the gel never sets hard, you can reopen the box later if you need to add another fitting or move one along the run, then close it back up and it reseals just as well.

Where It Works Best

This is a job for outdoor cable joints that will end up underground or somewhere damp, garden borders, driveway edges, anywhere a series of bollards or ground lights needs linking without a visible junction box on show. It also suits repairs or extensions to an existing run, since it can be opened, worked on, and resealed rather than replaced.

Collingwood Lighting

Collingwood Lighting designs and manufactures its LED products from Sywell, Northamptonshire, and has focused on LED technology since 2002. The brand says it was among the first to bring sealed for life, waterproof products like this one to the UK electrical wholesale market, an approach that shows in a connector built to be buried and forgotten about. Collingwood has also been awarded a Gold medal by EcoVadis, placing it in the top 5% of companies assessed globally for sustainability.

Good to Know

• Rated IP68, submersible to 1.3m, so it copes with wet ground or standing water
• Made from plastic, measuring roughly 93.5mm x 36mm and weighing 0.1kg
• Comes with a 1 year warranty
• Moonlight Design recommends installation by a registered NICEIC electrician for any outdoor wiring job

Questions People Ask

Can the JB4 be opened once it's installed?
Yes. The gel inside doesn't set hard, so the box can be opened, altered, and closed again without losing its seal.

How wet or deep can this go?
It's rated IP68 and submersible to 1.3m, so it's built for wet ground, standing water, or a straightforward underground burial.

What is the JB4 actually for?
It joins outdoor series wired lighting, such as a run of bollards or ground lights, giving you a sealed connection between two cables at each join.

Does it come with a warranty?
Yes, Collingwood covers the JB4 with a 1 year warranty.

93.5mm length x 36mm width

• Collingwood Residential Accessories Guide 2025

We offer free standard delivery on orders within the UK Mainland* (an additional fee applies for the Isle of Wight, the Isle of Man, the Scottish Isles, parts of Scotland, Northern Ireland, the Republic of Ireland, the Channel Isles and International).

*Collingwood orders under £150 incur a delivery fee of £9.95 inc. VAT.
*Any order under £49 incurs a delivery fee of £9.95.