Cable Identification: Heat Shrink Sleeve, Wrap Label or Tag
Three ways to identify a cable, each with a boundary. Conductor size, environment and the likelihood of later changes settle which one to use.
Cable identification looks trivial until it is wrong. Sleeves have to be cut off and terminals re-crimped, wrap labels blur within months in an oily cabinet, and tie tags take up space. Each option has its place.
The first: sleeves
A marker sleeve slides over the conductor end before the terminal is crimped and is locked in place once crimping is done. Heat shrink grades grip after shrinking, non shrink grades rely on elasticity. The advantages are mechanical security, abrasion resistance and indifference to oil, which is why they dominate industrial control cabinets. The limitation is timing: sleeves must go on before crimping, so adding or changing a number later means cutting the terminal off and redoing it.
Sleeves suit harnesses built in advance and not expected to change. Diameter has to match the conductor: too loose and the sleeve slides, too tight and it will not enter the terminal.
The second: wrap labels
The label folds around the conductor and the two ends stick to each other. It can be applied to cable already installed, without touching terminals, which makes it the workhorse for retrofit and maintenance work.
Two limits apply. Very small conductors leave too little area for the ends to bond, or the bond is so narrow that it opens at a touch, and below roughly 3 millimetres diameter the method struggles. In harsh environments, particularly continuous oil, coolant or UV exposure, paper and ordinary vinyl embrittle within months, so PET or a dedicated vinyl film is needed.
The third: tie tags and hanging plates
The label becomes a plate with a hole, fixed to the cable with a tie. It suits heavy cable, bundled runs and anything that must be read from a distance. The label area can be large, so type can be large enough to read a metre away, and nothing sits on the conductor surface to interfere with bending or heat dissipation.
The cost is space. In a densely packed duct a tag interferes with neighbours, and ties loosen over time and need checking. Data centre and switchgear mains use them most.
Matching the material
PVC sleeves are soft and cheap but tolerate little heat, deforming above roughly 80 degrees Celsius and unsuitable outdoors. Heat shrink adds heat and abrasion resistance at higher cost and an extra process step. PET film resists heat, solvents and dimensional change, making it the default for wrap labels. Vinyl film is flexible and suits irregular surfaces. Paper only belongs indoors, dry, and short term.
Printing
Cable labels are almost always thermal transfer with a resin ribbon. Resin resists solvents and abrasion; wax and wax-resin do not survive an oily cabinet. Print darkness should run a step higher than on ordinary labels, because cable marking uses small type with thin strokes, and low darkness breaks the strokes.
Two acceptance checks. Rub the print ten times with an alcohol wipe and see whether it holds. Wrap the label around cable of the correct diameter and rub it ten times by hand to see whether the ends open. Passing those two eliminates most field failures.
Three questions that settle it on site
How large is the conductor. Below 3 millimetres, use a sleeve; above 6, all three options work. Will the identification change after installation. If it might, use a wrap label or a tie tag; if not, a sleeve is cheaper and more secure. How harsh is the environment. Continuous oil, outdoors, or wide temperature swings push you straight to PET or heat shrink, and away from PVC and paper. Those three answers usually decide the method faster than any sample book.
