Step 10.77 — Protective-earth bonding¶
Step 78 of 80 with a helper · Chapter 10 — Wiring and Checkpoint #1
Parts:
- multimeter on Ω · tool
Do: Short the probes and note that reading. Then, one probe on the C14 earth pin, touch the other to each row below. On frame and plate, probe a screw head, T-nut or bare cut end.
Check
Every metal thing you can touch is bonded; nothing that carries current is, except the 24 V negative, bonded on purpose.
Helper Records each bonding reading the adult calls out; the adult holds both probes, cord out of the room.
What you're looking at
The last earth check. Every piece of metal a hand can reach must have a low-resistance path back to the inlet's earth pin, and nothing that carries current may have any path at all.
| Point | Expected |
|---|---|
| PE WAGO, any port | < 1 Ω |
| PSU 3 FG (⏚) terminal | < 1 Ω |
| Frame — the screw head of the PE lug fitted at 10.16, on the rear extrusion beside the Z-chain notch | < 1 Ω |
| Frame — a far corner, screw head or T-nut | < 2–3 Ω |
| Build plate — the M4×6 PE screw head | < 1 Ω |
| Extruder motor body (via the ESD ground and the umbilical, 10.67) | a few Ω or less |
| Bed heater L or N | OL |
| +24 V — PSU +V or any Vin + | about your 10.74 +V → −V reading, through the loads and the ESD bond (verify on bench). Never 0 Ω |
| −V / GND — PSU −V or any Vin − | a few Ω — expected, the ESD bond from 10.58 |
Every Ω figure is above your shorted-probe reading. A failed row here is a missing PE lead, anodising under a washer, or a probe on anodising. Fix it before Ch 11 closes the bay.
Source: LDO wiring guide § Connecting the FFC cable, Ethernet cable, USB cable and frame PE