Lugs, Ferrules, Heat-shrink, Glands
Hardware
The unglamorous hardware that makes wiring reliable and safe: lugs bolt wires to terminals, ferrules stop stranded wire from splaying in screw clamps, heat-shrink insulates and strain-relieves, glands seal cable entries.
What it looks like
Lugs, Ferrules, Heat-shrink, Glands
A typical hardware — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Wire gauge range
mm² / AWGEvery crimp part fits a specific conductor size — colour coded.
Stud/bolt size
mmRing lug hole must match the terminal stud (M3–M10).
Shrink ratio
:12:1 standard; 3:1 with adhesive for sealing joints.
Gland size / IP rating
M12–M25 glands; IP68 for outdoor boxes.
Markings
Crimp insulation colour = size (red 0.5–1.5 mm², blue 1.5–2.5, yellow 4–6); glands stamped with thread size and IP rating.
Standard values
Red/blue/yellow lug assortments, 1–10 mm ferrule kits, 2:1 heat-shrink assortments.
How to choose
Match the wire size exactly (a loose crimp is a future fire), use ferrules on every stranded wire entering a screw terminal, adhesive-lined shrink outdoors, and glands rated for the cable diameter.
Pinout & package
n/a — these are hardware. Use a ratcheting crimper matched to the terminal family; pliers-crimps fail.
Example circuits
- Ferruled wires into DIN-rail terminal blocks
- Ring lugs on a battery bank with adhesive heat-shrink
- Sealed gland bringing mains into an outdoor enclosure
Common failures
High-resistance joints from wrong-size or pliers-made crimps (they get warm — feel a suspect connector), wires pulling out where strain relief was skipped, water wicking into unsealed splices.
How to test
Tug test every crimp (it should hold the wire's rated pull), then millivolt-drop under load: a good crimp drops almost nothing; a warm terminal is a failing one.
Substitutes
Solder + adhesive heat-shrink can replace a butt splice (stiffer, less vibration-tolerant); never substitute undersized parts.