Engineering notes
Signal-cable screens: earth one end
A screened pair earthed at both ends can carry a loop bigger than the 0–10 V. One end, at the cabinet, as the maker writes.
“Screened cable” on the schedule is not the job finished. Sites earth both ends to be “safer”. On some runs the loop on the screen is larger than the 0–10 V — the reading ticks in time with the drive downstairs.
Most sensor and DDC makers want the screen earthed at one end, usually the controller cabinet. The far end is trimmed, not bonded to the housing. Unscreened untwisted cable will not hold 4–20 mA for 80 m next to a power tray.
Write it on the schedule: screened twisted pair, earth at the cabinet. Signal cable