An in-ground fitting's IP68 rating describes a sealed housing, tested in a lab. It says nothing about the join where the cable actually leaves the fitting, or the connections further down the run. This is the detail that separates an in-ground fitting that genuinely lasts 15 years buried in a lawn from one that fails within 18 months — and in the field, it's a very common failure, not a rare edge case.
Two routes water takes into an in-ground fitting
Most buyers only think about one of these. Worth stating both explicitly:
- Route A — through the housing seal or lens gasket. This is what the IP68 lab test actually measures: submerge the sealed housing, check nothing gets in.
- Route B — down or along the cable. Water runs down the outside of the cable jacket to the entry point, or wicks along the stranded conductor itself via capillary action between the individual strands — bypassing a perfectly good housing seal entirely, because the water never actually has to get past that seal to reach the inside of the fitting.
Why Route B is the one that actually kills fittings in the field
A fitting can be genuinely IP68 straight out of the box and still fail within a season if the cable entry isn't managed properly — because the failure path never goes anywhere near the tested seal at all. This is a very common failure pattern in the field: fittings turning up with water clearly having travelled up the inside of the cable and into the housing, with the housing seal itself completely intact.
This is routine, not rare
Cable-path water ingress is one of the most common in-ground lighting failures seen on real jobs — not a theoretical edge case. If an in-ground fitting is failing early and the housing seal looks fine, the cable entry and the join further down the run are the first place to look.
How manufacturers try to solve this
- Gel-filled or resin-potted cable entries — fully encapsulate the conductor right at the entry point, physically stopping capillary wicking along the strands before it can start.
- Double-sealed cable glands — add a compression seal directly on the cable jacket, on top of the housing's own seal.
- Pre-terminated quick-connect systems — designed so the field join happens inside a purpose-built connector, rather than as a raw twist-and-tape or wire-nut joint out in the open.
- Anti-siphon connector systems — some manufacturers now build connectors specifically designed to stop water travelling up the cable into the fitting via capillary action, rather than relying on the housing seal alone. This is a genuinely useful category to know about and ask a supplier for by function, even if the specific product detail for a confirmed recommendation is still being finalised on our end — worth checking this guide again for an update once that's locked in.
How to do a proper IP68 join in the field
1
Strip the cable cleanly
No nicked strands — a nicked strand is a wicking path in itself, regardless of what connector goes over the top of it.
2
Use a genuinely gel- or resin-filled IP68 connector rated for direct burial
Not a housing that's IP68 dry but relies on a grease that can be displaced over time or under mechanical disturbance.
3
Terminate in an accessible valve box where possible
Rather than a bare direct-buried joint — this makes future fault-finding possible without digging up the lawn.
4
Form a drip loop before the cable enters the fitting or gland
So water runs off the low point of the loop instead of tracking straight into the entry point.
5
Don't mix dissimilar metals at the join
Galvanic corrosion between the conductor, lug and terminal accelerates failure — especially relevant in the coastal corrosivity zones covered in our fitting construction guide.
6
Get the crimp and torque right
A loose crimp leaves a gap for water to wick into before it ever reaches the "sealed" part of the connector — the connector's own rating doesn't help if the crimp underneath it is poor.
7
Insulation-resistance test before backfilling
Cheap to check now with a megger. Expensive and disruptive to diagnose later once the garden bed is finished and the fitting is buried.
Practical takeaway — it all connects to material choice
Getting the cable join right ties directly back to the material and coating decisions in our fitting construction guide — the right base material and coating mean nothing if the cable join is the actual point of failure. Both need to be right together; neither substitutes for the other.
A good, verified how-to reference
We're planning to link a genuine, verified video walkthrough of a proper IP68 direct-bury join here — check back for an update, as we'd rather leave this blank than link something unverified.
Disclaimer: This guide is for general information purposes. Electrical connections, especially buried and in-ground work, must be carried out by a licensed electrician in accordance with AS/NZS 3000. See our
full disclaimer.