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#50791 04/11/05 11:39 PM
Joined: Apr 2005
Posts: 4
I
Itoh Offline OP
Junior Member
We are wirking for Russian construction project. According to our Russian partner, wiring methos for 24V DC instrument such as transmitter, solenoid valve, gas detectors, etc. shall be 3-wire system (+/- and earthing). As far as I know, the 3-wire method is very old Russian practice and it is not valid any more. Therefore we understand that europian style 2-wire system (+/- only) is sufficient for 24V DC instrument wiring. I appreciate if somebody give me your feddback/experience.

#50792 04/12/05 05:25 PM
Joined: Dec 2001
Posts: 300
M
Member
Typically in the US we use two wire (+,-) for these things. The negative (-) is at ground potential so there is no need for a separate earth ground.

In electronics (such as at the circuit board) there are many times when you will have 3 wires, one is at ground potential and one is positive relative to ground and one negative relative to ground. Fo example: +/- 9V which gives you 18V from + to -. but I've never seen this in control wiring.


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