Waterproof Copper Crimp Connections for Landscape Lighting
A properly sized and properly compressed copper crimp, protected inside a compatible waterproof housing, is one of our preferred connections for low-voltage landscape lighting. It combines a firm mechanical splice with a separate moisture barrier—two jobs that both need to be done well.
King Innovation offers two useful options: the compact 20245 DryConn Dry-Crimp kit and the 20810 CPC-C central point connector. Here is how they work, how to choose the sleeve size, and which tools belong in your installation kit.
Why use copper crimp connections for landscape lighting?
A crimping tool compresses a copper sleeve around the prepared conductors. A correctly made joint holds those conductors together without relying on the protective cap to keep the wires in contact. This makes the method especially appealing when you want a permanent splice and a consistent installation process across a property.
We recommend the method for installers who will take the time to match the sleeve, wire bundle and crimping tool. The advantage comes from the completed connection—not simply from choosing copper. An oversized sleeve, an overlooked fixture lead or an incomplete crimp can undermine the result.
Think of connection quality as part of the lighting design. A beautiful fixture still depends on the splice feeding it. When troubleshooting an intermittent light, inspect the connections along with the lamp and socket before assuming the fixture needs replacement.
How do waterproof copper crimp connectors work?
There are two parts to the system:
- The copper sleeve makes the electrical and mechanical connection. The tool compresses it around the stripped wires.
- The sealant-filled housing protects that connection. The completed splice goes into the specified protective housing, which is closed according to its instructions.
Installers often call these “grease tubes.” For the King systems discussed here, the moisture barrier is dielectric silicone sealant. It does not repair a loose crimp or replace proper contact between the copper conductors. A bare crimp sleeve is not a complete waterproof landscape-lighting connector.
King 20245 vs. King 20810: which should you use?
| Feature | King 20245 Dry-Crimp | King 20810 CPC-C |
|---|---|---|
| Format | Compact prefilled housing with an insert | Longer silicone-filled tube with wire channels and a latched lid |
| Where to consider it | Individual splices where its approved wire combination fits | Central connection points serving grouped fixture leads |
| Published conductor range | #18–#10 AWG copper | #18–#10 AWG copper |
| Maximum voltage | 50V | 50V |
| Pack | 25 filled housings, 25 small sleeves and 25 large sleeves | 25 CPC-C connectors with crimps and silicone tubes |
King identifies both systems for direct-burial use. Follow the exact connector instructions and permitted conductor combinations. Neither the word “waterproof” nor direct-burial suitability establishes approval for continuous underwater service.
20245: two crimp sizes in one kit
The King 20245 kit gives installers a choice of small or large copper sleeves. Choose the appropriate sleeve for each joint; you do not use both sleeves in one splice. Although the bag contains 50 sleeves, it has 25 waterproof housings, so it supplies up to 25 complete sealed splices.
20810: a tube for central point connections
The King 20810 CPC-C suits layouts that bring fixture leads back to a common connection area. Its tube is approximately 3-11/16 inches long. The finished crimp must reach the bottom of the sealant-filled tube; conductors then sit in the wire channels before the lid is latched. A larger housing does not give unlimited sleeve capacity.
Choosing between small and large copper crimp sleeves
Choose by the entire conductor combination, not just the largest wire. Record the gauge, quantity and solid or stranded construction of every conductor entering that splice. The #18–#10 overall range is not permission to combine any number of wires within it.
For example, a 12/2 cable continuing past a fixture with #18 leads creates a bundle of two #12 conductors and one #18 conductor on each side of the circuit. That is the combination to check against the sleeve instructions. This example explains counting; it is not a blanket approval for either sleeve.
- Small sleeve: use when the exact bundle falls within its permitted combinations.
- Large sleeve: use when the approved bundle requires it. A larger sleeve is not automatically a stronger connection for fewer or thinner wires.
- Neither sleeve fits: change the connector or junction plan. Never remove strands to make the wires fit.
Replacement copper sleeves are also available as 10-310C, 100-pack and 10-311C, 50-pack. Gardner Bender publishes respective gauge ranges of #18–#10 and #14–#8. These separate product ratings do not establish interchangeability with a King waterproof kit. Confirm the sleeve, housing and wire combination together; a sleeve's standalone rating cannot increase the completed system's limits.
Recommended tools: King four-way crimper and Milwaukee 7-in-1 pliers
King 46540 four-way crimper: Buchanan-style compression
The King Innovation 46540 four-way wire crimper is our dedicated tool choice for this type of copper-sleeve work. Installers often call this a Buchanan-style crimper; the product linked here is made by King Innovation.
Its cam-operated plungers apply even compression, and it adjusts for two sleeve sizes. King's instructions identify latch position A for small connectors and B for large connectors. Match the setting to the approved sleeve, then complete the compression as directed. Ordinary gripping pliers are not a substitute for an appropriate crimping tool.
Milwaukee 48-22-3078 wire stripper with built-in crimper
The Milwaukee 48-22-3078 7-in-1 wire stripper and combination pliers is a useful preparation tool for landscape-lighting work. It strips #8–#18 solid wire and #10–#20 stranded wire, and includes cutting, gripping and crimping functions. Its stranded-wire stripping range includes common #10 and #12 landscape conductors.
Milwaukee describes the built-in crimper for insulated and non-insulated terminals. Some Professionals prefer to crush the crimp as opposed to use a 4 way tool. For a dedicated four-way tool, choose the King 46540.
How to make and waterproof the splice
Disconnect power before working and follow the full instructions packaged with the connector. Keep the two conductors of a lighting circuit separate: a conventional two-wire connection needs a separate insulated splice for each circuit path.
- Plan the joint. Check the conductor combination and sleeve size. Allow cable slack so the splice does not carry tension.
- Prepare the housing in the correct order. For 20245, pass the conductors through the base ports before stripping and crimping.
- Prepare clean conductor ends. Use the correct stripping opening and the connector's specified preparation. Align strands and pre-twist where King's instructions require it.
- Make the crimp. Insert the bundle fully and use the specified indent-type crimping tool. Check that every conductor is captured; trim excess bare wire as directed.
- Complete the seal. On 20245, seat the conductors in the insert and snap it into the body. On 20810, seat the splice fully in the silicone tube, arrange the wires in the channels and latch the lid.
- Verify the installation. Check operation and fixture voltage under load before final placement. Restore power only after exposed connections are safely enclosed.
Do not substitute ordinary grease, household caulk or tape for the specified sealing system. King's 20245 instructions prohibit reuse. Plan fresh components when remaking a permanent crimp connection.
Common questions about waterproof crimp connections
Are copper crimps better than waterproof wire nuts?
We consider a correctly installed crimp-and-seal system one of the strongest options for a permanent landscape-lighting splice. Waterproof twist-on connectors can also work well when correctly selected and installed. Compare all three approaches in our landscape lighting waterproof connector guide.
Does the silicone conduct electricity?
No. The dielectric sealant protects the joint; the compressed copper connection carries the current. Adding more sealant will not fix a loose wire.
Can I use these connectors with 10/2 or 12/2 lighting cable?
Those individual conductor gauges fall within the published overall ranges, but the entire bundle must be approved for the selected sleeve. Count feeder conductors, outgoing cable conductors and fixture leads separately. Never combine both supply conductors in one crimp.
Do I need two waterproof connectors per fixture?
A typical two-wire fixture tap has two separate splices, so it generally needs two complete connector assemblies. Branching and central-point layouts require a count based on the actual wiring plan.
Build your connection kit
Start with King 20245 Dry-Crimp or King 20810 CPC-C, then add the King 46540 four-way crimper and Milwaukee 48-22-3078 combination pliers. Browse our landscape lighting wire connectors or send us the wire gauges and conductor count at each splice for help selecting components.
Manufacturer references: Dry-Crimp instructions; CPC-C instructions; 46540 tool instructions; Milwaukee 48-22-3078 specifications. Reviewed September 23, 2026.
- Atlantic Lighting