Step 10.18 — Colour groups are shorted¶
Step 18 of 80 · Chapter 10 — Wiring and Checkpoint #1
(no image — see text)
Parts:
- multimeter · tool
Do:
- One colour at a time, park one probe on the first node in its list and walk the other probe along every node after it.
- Rocker ON for the L and N lists, either position for PE.
Check
Every row beeps. For a row with an Ω figure, short the probes on Ω first and subtract that reading.
What you're looking at
You are proving that each conductor colour is one electrical node from the inlet pin to its last destination: out to the PSU screws, the relay, the bed and the frame. A core that never seated in its lever looks perfect from outside.
PE — green/yellow (rocker on or off — the earth path is never switched)
| From the C14 E pin to … | Expected |
|---|---|
| every occupied port of the PE WAGO | beeps, < 1 Ω |
| PSU screw 3 FG (⏚) | beeps, < 1 Ω |
| bed PE ring — probe the head of the plate's M4×6 screw | beeps, < 1 Ω |
| frame PE ring — probe its screw head | beeps, < 1 Ω |
| frame, far corner — a T-nut or bare cut end | beeps, < 2–3 Ω |
| PSU chassis — a bare case screw | beeps, a few Ω or less (the case is bonded to FG inside the supply) |
N — blue (rocker ON)
| From the C14 N pin to … | Expected |
|---|---|
| every occupied port of the N WAGO | beeps |
| PSU screw 2 N | beeps |
| bed N — the pad's N lead at its bed-WAGO port | beeps |
L — brown (rocker ON, fuse fitted)
| From the C14 L pin to … | Expected |
|---|---|
| the fuse, drawer in — it sits between the L pin and every row below, so those rows prove it in circuit | beeps |
| every occupied port of the L WAGO | beeps |
| PSU screw 1 L | beeps |
| SSR LOAD 2 | beeps |
To read the fuse alone: drawer out, probe cap to cap. It beeps; OL is a blown fuse. Refit the drawer before you walk the L list.
Bed L branch — a node of its own until the SSR conducts
| From SSR LOAD 1 to … | Expected |
|---|---|
| the Bed L extension's bed-WAGO port, and the pad's Bed L lead | beeps |
| SSR LOAD 2 | silent — that is step 10.21 |
A node that does not beep is a core that did not seat in its WAGO lever, or a screw terminal clamped on insulation. Re-strip and re-seat it, then repeat that colour's whole list.
Source: LDO wiring guide § Checkpoint 1