Best IP66 Enclosures for Outdoor Wiring: 2025 Expert Review
Oli at OR Electrics
Fully Qualified 18th Edition Electrician
If you live in Leeds, you know our weather is unforgiving. Whether it's driving rain or damp winter mornings, moisture is the number one enemy of outdoor electrics. A poorly sealed junction box isn't just a nuisance that trips your RCD; it's a potential fire hazard.
Many homeowners assume any plastic box will do, but there is a massive difference between a generic container and a proper IP66 rated enclosure. I frequently get called out to fix 'nuisance tripping' issues, only to find a waterlogged junction box that wasn't fit for purpose or wasn't installed correctly.
In this review, I've selected three IP66 enclosures that I encounter or use in the field. I've broken them down into a budget-friendly option for simple jobs, a professional bulk option for larger projects, and a compact solution for tight spaces.
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Specs vs. The Real World
The Spec: "IP66 Rating"
"The box is completely dust-tight and protected against heavy seas or powerful jets of water."
The rating is only valid if you seal the cable entry points correctly. If you drill a hole and don't use a proper stuffing gland or silicone sealant, that IP66 rating drops to zero immediately.
The Spec: "UV Resistant"
"The plastic won't degrade in sunlight."
Cheaper plastics become brittle after a few years of direct UV exposure, leading to cracks. It's always worth mounting enclosures in the shade where possible to extend their lifespan.
My Top 3 Recommendations
Three options to cover different needs and budgets
Knightsbridge JB009BK Large IP66 Weatherproof Enclosure in Black
Knightsbridge
This large enclosure from Knightsbridge is an excellent choice for DIY projects where you need a bit more room to manoeuvre. The extra internal space is perfect if you are housing bulky connectors or a small LED driver for garden lights. It's robust enough for typical residential use in Leeds gardens.
The Good
- Spacious interior makes wiring easier for beginners
- Robust polycarbonate construction capable of withstanding impact
- Compliant with UK wiring regulations
The Bad
- Large footprint may look unsightly on smaller walls
- Requires careful drilling for cable entry to maintain IP rating
Installer Tip:
Use the extra space to create a 'drip loop' inside if possible, or ensure your external cables loop downwards before entering the box. This prevents water from running down the cable and straight into the terminals.
Priced at £12.99 at the time of writing
Check Price on AmazonWISKA COMBI 308/5/S Enclosure, IP66, Junction Box (10 pieces)
okoium
Whilst the listing brand name appears generic, these are genuine Wiska Combi boxes—the industry standard for electricians across the UK. This pack of 10 is fantastic value for anyone planning a larger garden lighting project. The self-sealing membrane entries mean you often don't need separate glands, speeding up installation significantly.
The Good
- Industry-standard reliability trusted by professionals
- Self-sealing membranes save time and ensuring a tight seal
- Excellent domed lid provides extra internal space
The Bad
- Bulk buy only (pack of 10) - higher upfront cost
- Slightly smaller internal working space than the large Knightsbridge box
Installer Tip:
These boxes are superb because of their domed lids. Even if the box feels full, the lid usually accommodates the Wago connectors easily. Always push the cable through the membrane just enough to create a seal—don't over-insert.
Priced at £49.99 at the time of writing
Check Price on AmazonKnightsbridge JB008BK Medium IP66 Weatherproof Enclosure in Black
Knightsbridge
Sometimes you don't have the wall space for a massive enclosure, especially on the narrow brick returns found on Victorian terraces in Leeds. This medium-sized option from Knightsbridge offers the same robust protection as its larger brother but in a 125x86mm footprint, making it ideal for discreet installations behind security lights.
The Good
- Compact size is easier to hide
- Very affordable price point
- Durable impact-resistant polycarbonate
The Bad
- Restricted internal wiring space can be fiddly
- Not suitable for housing bulky transformers
Installer Tip:
Because space is tighter here, preparation is key. Strip your cables neatly and use lever-style connectors (like Wagos) rather than screw terminals to make it easier to fold everything into the box before closing.
Priced at £8.75 at the time of writing
Check Price on AmazonFrequently Asked Questions
What does IP66 actually mean?
Do I need to clean the enclosure?
Can I bury these enclosures underground?
Do I need an electrician to install an outdoor junction box?
Why is my outdoor lighting tripping the electrics?
Are black enclosures better than grey ones?
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