A commissioning engineer at a water treatment site spends a whole afternoon on a pump starter panel whose drive will not start on remote. The culprit is two control cores swapped on the terminal strip. Ferrules match the schematic perfectly. The cores simply landed one terminal apart. The wireman who built it has turned out dozens of panels and is known as careful.
That is how wiring quality behaves in a panel shop. Each cabinet is a fresh drawing, and one person often wires it from gland plate to door. Nothing about the build repeats, so there is no jig to catch a habit. The quality that leaves the shop is, in practice, the quality of whoever held the crimping tool.
Why it is so personal here
A motor line can lean on fixtures and repeat counts. A panel shop cannot. The wireman reads the schematic, plans duct runs, cuts lengths, strips, crimps, ferrules and lands every core alone. Many defects are hidden the moment the duct cover goes on. A strand cut while stripping, a bootlace ferrule crimped with the wrong die, or a terminal screw a quarter turn short all look identical to a good job from the front.
Where each slip surfaces
- At the bench: two cores under one screw, ducts so full the cover bows, labels upside down from the door.
- At functional test: an interlock that does nothing, an indication lamp on the wrong feeder, a PLC input that never changes state.
- At commissioning: swapped control wires, a loose neutral that heats under load, a CT shorting link left open, or a door earth jumper never fitted.
- Months later: a crimp that loosens with vibration, so a drive trips at random and the customer stops trusting your name.
The bill for a loose crimp
A slip caught at the bench costs minutes. Caught by the tester, it costs an hour and some temper. Caught on site, it costs a commissioning engineer's travel, nights in a lodge and a customer watching the clock. People pay as well. Good wiremen resent fixing others' work unpaid, testers and wiremen start blaming each other, and the steadiest hands drift to shops where rework is rarer.
Why the same faults return
- No written standard. Each senior has a style, and helpers copy the nearest one, faults included.
- Pay follows seniority or speed. Nobody earns more for panels that clear functional test without a single correction.
- Site faults never reach the bench. The commissioning engineer fixes the panel and moves on. The wireman never hears.
- Testing gets squeezed. When dispatch is tight, the final check shrinks, and site becomes the test bay.
Small tools, big differences
Some wiring faults start with kit rather than hands. Think of a ratchet crimper with a worn die, or a stripper set one gauge too fine. A blunt side cutter frays strands. A ferrule printer nobody refilled means labels get handwritten. Each nudges a careful wireman towards a bad joint. Issue personal crimping tools against signature, check dies on a schedule, and keep a spare ferrule printer ribbon in stores. The tool crib is part of wiring quality.
The repair, in order
- 1
Write a one-page wiring standard with photographs
Lug and bootlace sizes per core, one core per terminal unless stated, ferrule reading direction, duct fill limit, bend radius at terminals, door harness spiral, earth jumpers and label position. Photograph a good and a bad example of each.
- 2
Give every wireman a self-check sheet
Twelve lines, ticked before the panel leaves the bench: terminal tightness by tug, ferrules against the wire schedule, spare cores marked, CT links closed, earth continuity.
- 3
Put a wireman's code inside each panel
A small label on the door inside, also written on the job card. It exists so site faults can find their way home for coaching, never for a fine.
- 4
Add a second-person check before functional test
Someone other than the builder walks the panel against the drawing for an agreed sample of terminals. Where headcount is tiny, two wiremen swap panels for this.
- 5
Feed site faults back within a week
The commissioning engineer logs each fault with the panel number. Within seven days the supervisor shows the wireman that photo, at his own bench.
- 6
Grade wiremen by panels built alone and cleared clean
Helper, junior, wireman and senior, with a sample panel and functional test record at each rung, and pay to match.
Wireman grades priced against neighbouring shops are discussed under benchmarking pay for panel builders. Every rung from helper upward appears in the wireman training route.
What to check first
- Go through last quarter's commissioning fault notes and mark which were wiring rather than design.
- Ask three wiremen to show you the shop's wiring standard. If they each describe a different one, there is none.
- Find out who checks a panel before functional test, and whether that person ever wired it.
- Ask a senior wireman when he last heard about a fault on one of his own panels from site.
Measuring without scaring people
Panels clearing functional test untouched make the fairest yardstick for a wireman. It goes wrong when people are fined for rework they report honestly, because then rework simply stops being reported. The panel shop performance page sets out measures that reward clean work without punishing candour. Late drawing revisions, commissioning travel and peak overtime are discussed on the control panel makers page. To see how panel shops compare with winding and busbar trades, visit our HR guide for electrical equipment firms.
