Quick Answer: Match the splice kit to your pump cable’s wire gauge and conductor count before anything else— most residential submersible pumps run 14-8 AWG stranded cable with either 2, 3, or 4 conductors, and the generic “wire splice kit” results that dominate search (small-gauge, gel-filled twist-on connectors built for landscape lighting) don’t fit that cable or survive being lowered down a well casing. The Gardner Bender 600V Underground Pump Wire Splice Kit (8-14 AWG, about $11-$17) covers the widest range of common pump gauges with heat-shrink, mastic-lined connectors; the Boshart 3-Wire kit (14/12/10 AWG, about $6.59 for 3 splices) matches 3-wire control-box pumps exactly; and a 4-wire #10-14 AWG kit (about $10.39) fits 4-wire deep-well setups.
A submersible well pump’s underground electrical connection is only as reliable as the splice joining the pump’s short motor leads to the longer drop cable running up to the surface. Get the wrong kit—wrong gauge, wrong conductor count, or a connector never meant to go underwater—and the splice is the thing that fails, usually at the bottom of the well where it’s the hardest and most expensive part of the system to reach.
Splice kits compared
| Kit | Wire gauge | Conductors | Best for | Price |
|---|---|---|---|---|
| Gardner Bender 600V Underground Pump Kit | 8-14 AWG | 2 | Most 2-wire pumps (best overall) | ~$11-$17 |
| Boshart 3-Wire Heat Shrink Kit (3-pack) | 14/12/10 AWG | 3 | 3-wire control-box pumps | ~$6.59 |
| 4-Wire #10-14 AWG Splice Kit | 10-14 AWG | 4 | 4-wire deep-well pumps | ~$10.39 |
1. Gardner Bender 600V Underground Pump Wire Splice Kit — Best Overall
Gardner Bender 600V Underground Pump Wire Splice Kit
- Covers the 8-14 AWG range most residential 2-wire submersible pump cable falls into, so it fits a wider range of pumps than smaller-gauge kits without needing to special-order.
- Mastic-lined heat-shrink tubing bonds to the cable jacket as it shrinks, sealing the splice rather than just insulating it—the actual waterproofing method, not the crimp itself.
- 600V rating matches standard residential well pump circuits with margin to spare.
- Widely stocked at hardware stores and electrical suppliers, so a replacement is easy to find on short notice if a pump needs to come out of the well.
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The Gardner Bender kit is the safe default for the most common case: a 2-wire pump, standard residential gauge, and a part that’s easy to source again later if the splice ever needs to be redone.
2. Boshart 3-Wire Heat Shrink Splice Kit — Best for Control-Box Pumps
Boshart 3-Wire Heat Shrink Splice Kit (3-pack)
- Sized for 3-wire pumps—the type wired through a separate above-ground control box rather than a control box built into the pump itself—with one connector-and-tube set per conductor.
- Covers 14, 12, and 10 AWG, the three gauges most common on residential 3-wire drop cable.
- Sold as a 3-pack because a 3-wire splice needs all three conductors joined at the same point in the cable, not just one.
- Not a fit for 2-wire pumps, which only need two connectors—check your control box (or lack of one) before buying.
If the pump has its own separate control box mounted near the pressure tank, see our well pump control box guide for how that box’s starting circuitry relates to the splice down in the well—this is the kit that matches that setup.
3. 4-Wire #10-14 AWG Splice Kit — Best for Deep-Well / Grounded Setups
4-Wire #10-14 AWG Submersible Cable Splice Kit
- Adds the fourth connector-and-tube set a grounded 3-wire-plus-ground pump needs, which a standard 3-wire kit doesn't include.
- 10-14 AWG range matches typical drop cable on wells deep enough to need the extra ground conductor as a separate run rather than relying on casing grounding alone.
- Same crimp-then-heat-shrink installation method as the smaller kits, just scaled to one more wire.
- Confirm all four conductors are the same gauge before buying—some 4-wire pump cable runs a smaller ground wire than the three power conductors, which this kit's connectors may not match.
A 4-wire setup is the one most likely to need two kits rather than one if a well also uses an inline check valve near the pump that was removed for the same service call—buy enough connectors for every joint being reopened in the same trip.
The gauge trap: most “wire splice kit” results aren’t rated for pump cable at all
Searching “wire splice kit” turns up mostly small-gauge, gel-filled twist-on connectors—3M’s DBR/Y series is the best-known example—built for landscape lighting and sprinkler-valve wire. Those connectors are rated for roughly 18-10 AWG, which can overlap with pump cable on paper, but they’re designed to sit buried flat in soil, not to be crimped onto stranded pump cable and then dragged down a well casing on a drop pipe during installation or pulled back up during a repair. The kits built specifically for submersible well pumps use crimped stake-on (butt) connectors instead of twist-on connectors, sealed with heat-shrink tubing rather than a pre-filled gel cap—a mechanically tougher joint matched to the cable’s exact gauge, which is why the three kits above are sold by wire gauge and conductor count first, brand second.
How contractors actually make the splice
Installation guidance published by Boshart (a manufacturer of these kits) and trade coverage in The Driller both describe the same sequence: strip and clean several inches of insulation so the heat-shrink tubing’s adhesive can bond, seat each wire fully into the stake-on connector against its internal stop without forcing it past that stop, then center the heat-shrink tube over the crimped connector and heat from the middle outward until adhesive shows at both ends. The spacing matters as much as the technique—per Boshart’s own installation instructions, splices should be staggered by a minimum of about 4 inches for 3-inch tubes and about 7 inches for 6-inch tubes, so the joined cable doesn’t form one bulky lump at a single point that’s more likely to scrape or catch against the well casing as the pump goes down (or comes back up for service). Most installers also tape the pump cable to the drop pipe on both sides of each splice for physical support, independent of the splice itself holding the electrical connection.
Confirm the wire count before you buy
A 2-wire pump has a control circuit built into the pump itself and needs only two spliced conductors. A 3-wire pump relies on a separate above-ground control box to start the motor and needs three. A 4-wire pump is the same 3-wire pattern plus a dedicated ground conductor run as a fourth wire rather than relying on the casing for grounding. Buying a 2-wire kit for a 3-wire pump (or vice versa) is the single most common mismatch—check the existing control box, or the cut end of the old cable if the pump’s already pulled, before ordering a replacement kit.
The bottom line
Gauge and conductor count decide the right splice kit, not brand name—a kit rated for the wrong wire size or missing a conductor won’t seal properly even if every other step is done right. The Gardner Bender 600V kit covers the common 2-wire case, the Boshart 3-wire kit matches control-box pumps exactly, and the 4-wire kit adds the ground conductor deep wells often run as a separate wire. Whichever kit fits, stagger the splices per the manufacturer’s spacing guidance and tape the cable to the drop pipe on both sides—the splice is only as reliable as the installation around it.
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