Individually labelling 0VDCs
Individually labelling 0VDCs
(OP)

G'Day All
In Oil & Gas projects I have seen the 0VDC 'feeds' individually labelled - see the photo above. All the 0VDCs, i.e. 0VDC1, 0VDC2, eventually connect to the same 0VDC on the power supply.
Why is this practice used? Does it provide some troubleshooting benefits?
Cheers Michael





RE: Individually labelling 0VDCs
On most things in field wiring you don't ever want daisy-chain wiring hence separate wires for a "star" pattern. You invite this by separate screw/terminal points.
Often the wiring in the control panel continues this scheme so the labeling does what it can to continue it. If the terminals were all labeled identically as 0VDC it would cause cheap installations where installers consider all the OVDC the same and they aren't really. Wiring may be twisted pairs clear into the controllers with the star point inside somewhere.
Keith Cress
kcress - http://www.flaminsystems.com
RE: Individually labelling 0VDCs
What do yuo mean when you say 'the star point inside somewhere?
RE: Individually labelling 0VDCs
Single terminals for a signal wire with a common return is different to what you've shown in the drawing, as itsmoked suggested, you invite discrete pairs by putting discrete terminals in. Inadvertent 0V connections can do funny things with 4-20mA loops, voltage transducers and the like. Its also relevant with 2 wire sensors, each designation refers to the specific sensor return wire, not the common terminal its connected to.
RE: Individually labelling 0VDCs
Normally I would jumper all the negatives down the RH side of the terminal strip with the bottom one going back to the point of origin for extra security, I assume -24 is grounded also.