Coastal Source assembly
Pre-twisting the wires is correct with a dry wire nut, and it is what makes a buried connection leak.
A silicone-filled connector works by forcing gel into the gaps between the strands. Twisting the wires together first turns them into an irregular bundle that pushes the gel out before the seal forms. It is named as the most common mistake electricians make when they switch to these, which is to say the failure comes from competence rather than carelessness.
The fixture is almost never what failed
Landscape lighting fails at its connections. That is not a controversial claim in this trade, and one manufacturer states its position on the cheapest version of the problem plainly: they do not include pierce-point connectors in their boxes because they know they fail. When a system that worked for two seasons starts losing fixtures, the odds heavily favor a splice in the ground rather than anything in the light itself.
Which puts a lot of weight on a five minute task, and the task has a trap in it that specifically catches people who know what they are doing. A silicone-filled direct burial connector is a wire nut pre-loaded with non-hardening gel, and it works by forcing that gel in among the copper strands as the nut is twisted on. The reflex of anybody who has done electrical work is to twist the conductors together first and then cap them, which is correct practice with a dry nut and is exactly wrong here.
The guidance is unusually direct about who this catches: it is described as the most common mistake electricians make when switching from standard to silicone-filled nuts. Pre-twisting creates a large irregular bundle that pushes the silicone out of the connector before the seal is formed. The correct method is to strip the wires, align them side by side, push them straight into the gel-filled nut, and then twist the nut itself, which drives the gel into the gaps rather than out of them.
So the failure mode here is not ignorance. It is a correct habit imported from an adjacent trade, which is the same shape as several other things in this category and is why a five minute job is worth a page. The rest of it is choosing the right part, burying it at the right depth, and knowing what a failed splice looks like when you dig it up.
What it actually takes
Every individual step is minutes. The reason systems fail is that the wrong five minute version is indistinguishable from the right one until year three.
| Model | Time | People |
|---|---|---|
| Calling 811 before any diggingFree, and required in every state. | lead time | 1 |
| Killing power properlyTimer off, breaker off, and unplug the transformer. | 5 minutes | 1 |
| Choosing connectors rated for direct burialNot wet location. Different UL subcategory. | 15 minutes | 1 |
| Matching connector size to gauge and wire countToo large is loose, too small leaves copper exposed. | 10 minutes | 1 |
| Making a splice correctlyStrip, align, push in, twist the NUT. Never pre-twist. | 3 minutes each | 1 |
| Trenching to depthSix inches for low voltage. Deeper is not worse. | the bulk of the job | 1 |
| Sleeving under hardscapePVC conduit under walks and driveways. | 1 to 3 hours | 1 |
| Recording or hubbing splice locationsA buried splice you cannot find is a future excavation. | 30 minutes | 1 |
| Diagnosing an existing failureDig one splice and look at the copper. Green or bright. | 30 minutes | 1 |
The single most useful diagnostic in this category costs nothing: dig up one connection and look at the color of the copper. It tells you which of three completely different problems you have.
What to get right, specifically
Strip, align, push in, then twist the nut. Do not pre-twist the wires
This is the whole page and it is counterintuitive enough to be worth stating twice. A silicone-filled connector seals by forcing non-hardening gel in among the copper strands as the nut goes on. Pre-twisting the conductors first, which is correct with a dry wire nut and is what most people do without thinking, creates an irregular bundle that pushes the gel out of the connector before any seal forms. Guidance names it as the most common mistake electricians make when switching to these connectors. Strip about half an inch, lay the conductors side by side, push them straight into the gel, and twist the nut. If gel squeezes out around the skirt as you twist, that is the seal forming rather than sealant being wasted.
Wet location and direct burial are different ratings, not synonyms
This is the shopping trap and the packaging does not help. Weatherproof or wet location wire nuts are designed for above-grade outdoor use inside junction boxes. Direct burial wire nuts have enhanced sealing and materials engineered for constant soil contact, moisture and pressure, and the two carry different UL 486D subcategories which cannot be used interchangeably. So a connector honestly and accurately labeled for outdoor use can still be the wrong part for a splice you are about to bury. The instruction is to look for explicit language saying suitable for direct burial or for below-grade applications, rather than settling for wet location.
Green copper tells you which of three problems you have
The most useful thirty seconds in this whole category, and it separates three different failures that all present as dim or dead fixtures. Dig up one connection and look at the copper. Green corrosion means the splice has been letting water in, and the fix is to cut back to clean bright copper and remake it properly. Clean corrosion-free copper with dim lights at the end of the run means the run is too long for what is feeding it, which is a voltage drop problem and a completely different repair. And a system where the splices are clean and the drop calculation is fine points upstream at the transformer. One visual check, three diagnoses, and it costs a trowel and a few minutes.
Six inches for low voltage, and the other numbers are not yours
Burial depth gets muddled because people mix circuit types. For low voltage under thirty volts the figure is typically six inches minimum. For a residential 120 volt branch circuit with GFCI protection it is twelve inches. For direct burial UF cable without GFCI it is twenty-four inches, or eighteen in PVC conduit. Only the first of those applies to landscape lighting, and local requirements may be more stringent, so check. Six inches is not an arbitrary number either: it is deep enough to be below aerators, edgers and trowels, which is the actual threat to a landscape cable.
You do not need conduit in soil, and you do need it under hardscape
A useful pair of facts that saves both money and future excavation. In normal soil, conduit is not required for low voltage landscape wiring provided the cable is rated for direct burial and buried to depth, so trenching and laying cable directly is the correct approach rather than a shortcut. Under hardscape it is the opposite: run PVC conduit through any section passing beneath a sidewalk, driveway or patio. That is not about protection from moisture, it is about ever being able to replace that cable without breaking concrete, and it is the difference between a twenty minute repair and a masonry job.
Electrical tape is not a seal, and an indoor nut is not a connector
Stated bluntly by suppliers because it is the most common improvised repair. Electrical tape is not waterproof: it peels, water gets in, and the wire corrodes, so taping a splice is delaying the next repair rather than making one. Ordinary indoor wire nuts are described just as directly, as little plastic cones that are not sealed and will fill with water. There is a code dimension too, since the NEC requires connectors listed for wet locations when installed underground and you cannot tape up a wire nut that is not so listed. If you are genuinely stuck, self-fusing silicone tape, the kind that stretches and bonds to itself, is meaningfully better than vinyl, but tape should never be the primary seal on anything going in the ground.
Size the connector to the wires, and keep it out of the dirt while you work
Two small things that decide whether a correctly chosen connector actually works. Size matters in both directions: a nut too large gives a loose connection, and one too small leaves copper exposed, so match it to the gauge and the number of conductors being joined rather than using whatever is in the pouch. Then a practical detail almost nobody mentions: keep the connectors off the ground while you are working, hanging or resting on a rock, so soil does not clog the sealant before the splice is made. A connector packed with dirt cannot seal around copper, and it will look identical to one that did.
Consider a hub, and consider whether you will ever find the splice again
A daisy chain of buried splices is a system where every future repair starts with a shovel and a guess. Hub connectors gather several fixtures at a single point instead, and some are designed to be opened afterward: VOLT describes a junction hub using clamp-type connectors so wires can be added or removed during and after installation, and a micro-junction direct burial connector with micro-clamps and a silicone reservoir for hubs that must be buried. Whichever approach you take, record where the connections are. A splice that is properly made and completely unfindable is only half of a good installation, and the person looking for it in five years may not be you.
Before you make the first splice
Call 811 and wait for the locate before any trenching.
Turn the transformer off at the timer and the breaker, and unplug it.
Buy connectors explicitly labeled for direct burial or below-grade use, not just wet location.
Check the connector rating covers your wire gauge and the number of conductors per splice.
Confirm the cable itself is rated for direct burial.
Have PVC sleeving for any run crossing under a walk, drive or patio.
Plan trench depth at six inches minimum for low voltage, and check local requirements.
Decide whether hubs make sense, and plan how you will record splice locations.
Who this is really for
Anyone whose landscape lighting has started losing fixtures. The instinct is to suspect the lights, and the odds strongly favor a splice in the ground. One dug-up connection and a look at the copper usually settles it in a few minutes.
It also matters for anybody installing a system they intend to keep. The connections are the cheapest part of the job and the part that determines whether year three is uneventful. Doing them correctly costs an extra few minutes per splice, and one supplier frames the trade honestly: five minutes to strip wires and use a silicone-filled nut saves hours of troubleshooting in the mud a year later.
The case for having somebody do it is that the correct method here is counterintuitive, and the incorrect method is the one that experience teaches. Somebody who installs these knows not to pre-twist, knows wet location is not direct burial, sizes connectors to the conductors, keeps them out of the soil while working, sleeves under hardscape, and leaves a record of where the splices are. None of that is visible on handover day, which is exactly why it is worth paying for and exactly why it gets skipped.
What an installer does
- Calls 811 and waits for the locate before trenching.
- Kills power at the timer and the breaker and unplugs the transformer before working.
- Uses connectors explicitly listed for direct burial rather than wet location.
- Strips and aligns conductors and twists the nut, never pre-twisting the wires.
- Sizes each connector to the gauge and number of conductors in that splice.
- Keeps connectors clear of soil while working so the sealant is not contaminated.
- Trenches to at least six inches for low voltage, and deeper where local rules require it.
- Sleeves any run crossing under hardscape in PVC conduit.
- Uses hubs where they reduce the number of buried splices or keep them serviceable.
- Cuts back to clean bright copper when remaking a corroded connection.
- Records splice and hub locations for whoever services the system next.
Get it built by someone who has built one before.
Tell us your ZIP and what you bought. Installers near you will quote you directly, and you deal with them, not with us.
Questions people ask
Should I twist the wires together before putting on a waterproof wire nut?
No, and this is the mistake that catches experienced people. A silicone-filled connector seals by forcing gel in among the copper strands as the nut is twisted on. Pre-twisting creates an irregular bundle that pushes the gel out before a seal forms, and it is named as the most common mistake electricians make when switching to these connectors. Strip, align the conductors side by side, push them straight into the gel, then twist the nut.
Is a weatherproof wire nut the same as a direct burial one?
No. Wet location connectors are intended for above-grade outdoor use in junction boxes. Direct burial connectors have enhanced sealing and materials engineered for constant soil contact, moisture and pressure, and the two carry different UL 486D subcategories that cannot be used interchangeably. Look for packaging that explicitly says suitable for direct burial or below-grade, rather than accepting wet location.
How deep should low voltage landscape wire be buried?
Typically six inches minimum for circuits under thirty volts, and local requirements may be stricter. The other numbers people encounter belong to different circuits: twelve inches for a GFCI-protected 120 volt branch circuit, and twenty-four inches for direct burial UF cable without GFCI, or eighteen in conduit. Six inches puts a landscape cable below the aerators, edgers and trowels that actually threaten it.
How do I tell whether my problem is the connections or something else?
Dig up one connection and look at the copper. Green corrosion means water has been getting into the splice, and the fix is cutting back to clean bright copper and remaking it. Clean copper with dim fixtures at the end of a run points at voltage drop and a run that is too long for what feeds it. Clean copper and a sound drop calculation points upstream at the transformer. One visual check separates all three.
Can I just tape the connection?
No. Electrical tape is not waterproof: it peels, water gets in, and the copper corrodes, so taping is delaying the next repair rather than making one. Ordinary indoor wire nuts are equally unsuitable, being unsealed cones that fill with water. The NEC also requires connectors listed for wet locations underground and you cannot tape up a nut that is not so listed. Self-fusing silicone tape is better than vinyl in an emergency, but tape should never be the primary seal.
Do I need conduit for landscape lighting cable?
Not in normal soil, provided the cable is rated for direct burial and buried to depth. Do use PVC conduit for any section running under a sidewalk, driveway or patio, and that is about future access rather than moisture: a cable sleeved under hardscape can be replaced, and one buried directly under concrete cannot without breaking it.
Installers.org is not affiliated with, endorsed by, or sponsored by Coastal Source, VOLT Lighting, or any connector manufacturer or supplier referenced here. All marks belong to their owners and are referred to here only to describe the installation services that independent installers on this directory provide. Burial depths, connector listings and splicing rules vary by circuit class and by jurisdiction and local requirements may be more stringent than the figures given here: verify against the code adopted where you live and the listing on the products you buy. Line voltage work, including the supply feeding a transformer, is for a licensed electrician.