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  1. #1
    Join Date
    Aug 2006
    Posts
    2,609

    RTD Temperature Sensor Ground.

    I have a RTD Temperature sensor, that I'm using till I get my new ones. It is spliced, and I spliced the Shield. When I move the Cable near the controller or touch the control panel I get erratic readings. Shield is not grounded on controller end. Is the shield bonded to the SS sensing bulb or does the lead end need to be grounded?
    BTW the control cabinet is bonded to the Breaker panel.

  2. #2
    Join Date
    Mar 2005
    Location
    Pacific Time Zone
    Posts
    4,224
    Is your SS sensing bulb well attached to a conductive material? Also the attached material can't be painted.

    The purposed of a shield is to provide a one way path to ground to drain any impedence created on the cable. If you are grounded at both ends you defeated the purpose of the shield.

    I would ground the opposite end to the sensing bulb and make sure the sensing bulb is mounted onto a non-conductive material. This kind of goes back to the reason the want you to use actual ground screws when you attach something to ground and not just sheet metal screws. The ground screws have more threads per in and therefore are more 'conductive' due to the added surface area contacted. Point is that it is unlikely you are getting a good ground with you sensing bulb anyway.
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  3. #3
    Join Date
    Aug 2006
    Posts
    2,609
    Before I went to Lunch, I noticed the SS Bracket was attached to the Walk-in roof with a galvinized sheet metal screw. The more I look at this Lab Grade Walk-in the more shoddy work I find. It had a drop ceiling in it, I've removed it over their protest. The Fluorescent light fixture is just a drop in 2 x 4, wired with Romex no less. I've Rewired the control panel, am making a correct wiring diagram. Also I'm writing a squence of operation for it. The lab people go home at 2 o'clock, every Friday,must be nice for them. Took me an hour and half to get my tools and laptop. The Four RTDs have three splices each in them, one they mixed up the wires.

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