Eugene's DIY Den Posted February 7, 2022 Share Posted February 7, 2022 (edited) I'm trying to identify what's causing a false trigger on a zone and think it's possibly a contact that's not closing properly (When I close a window slowly, the contact doesn't close, so maybe the magnet is too weak for the spacing., or the reed switch is just gone bad. This is a new problem) Resistance is 9 MOhm for the loop open and 38 ohms it's closed. I would have thought that the 9 MOhm is low and the loop resistance should be higher on open circuit. Weather is really damp, so I'm thinking condensation on the insides of contacts or oxide deposits are contributing to the low reading. Interestingly, resistance is 7 MOhm with probes one way and 9 MOhm with them reversed, so maybe coupling of voltages or electrochemical action between wires and screws is responsible. Edited February 7, 2022 by Eugene's DIY Den Talking Tools, a Facebook group for discussing anything tool/DIY related. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/ Share on other sites More sharing options...
sixwheeledbeast Posted February 7, 2022 Share Posted February 7, 2022 (edited) Do tests with the contact removed on open and closed circuit, compare difference you'll find your answer. Never do tests while circuits is connected to the controls. Edited February 7, 2022 by sixwheeledbeast typo Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513673 Share on other sites More sharing options...
james.wilson Posted February 7, 2022 Share Posted February 7, 2022 3 minutes ago, sixwheeledbeast said: Do tests with the contact removed on open and closed circuit, compare difference you'll find your answer. Never do tests while circuits is connected to the controls. qfa securitywarehouse Security Supplies from Security Warehouse Trade Members please contact us for your TSI vetted trade discount. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513675 Share on other sites More sharing options...
Eugene's DIY Den Posted February 7, 2022 Author Share Posted February 7, 2022 (edited) One leg of the loop is removed from the terminals in the control panel, I wouldn't be measuring the resistance of a circuit that's powered. So the circuit is open and no current can flow in the loop to influence the meter. Edited February 7, 2022 by Eugene's DIY Den Talking Tools, a Facebook group for discussing anything tool/DIY related. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513676 Share on other sites More sharing options...
sixwheeledbeast Posted February 7, 2022 Share Posted February 7, 2022 How do you know there isn't cable damage and it's not looping back through mains earth? 1 Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513677 Share on other sites More sharing options...
Eugene's DIY Den Posted February 7, 2022 Author Share Posted February 7, 2022 (edited) 4 minutes ago, sixwheeledbeast said: How do you know there isn't cable damage and it's not looping back through mains earth? That's possible. Is 0v on this panel connected on the board to earth? (or is this the case in general for panels?) Edited February 7, 2022 by Eugene's DIY Den Talking Tools, a Facebook group for discussing anything tool/DIY related. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513678 Share on other sites More sharing options...
sixwheeledbeast Posted February 7, 2022 Share Posted February 7, 2022 No idea, but most panels you can get earth loops like this, hence a method of testing that rules it out. 1 Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513679 Share on other sites More sharing options...
Eugene's DIY Den Posted February 7, 2022 Author Share Posted February 7, 2022 4 minutes ago, sixwheeledbeast said: No idea, but most panels you can get earth loops like this, hence a method of testing that rules it out. Ok, I'll disconnect two legs of the loop and see what results I get. Talking Tools, a Facebook group for discussing anything tool/DIY related. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513680 Share on other sites More sharing options...
MrHappy Posted February 7, 2022 Share Posted February 7, 2022 3 hours ago, Eugene's DIY Den said: Resistance is 9 MOhm for the loop open and 38 ohms it's closed. you holding the conductors onto the test probes ? 1 1 Mr Veritas God Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513686 Share on other sites More sharing options...
Eugene's DIY Den Posted February 7, 2022 Author Share Posted February 7, 2022 (edited) 9 minutes ago, MrHappy said: you holding the conductors onto the test probes ? No, I thought about that. I'm qualified in this area, so it rules out me doing all the silly things Good point though. Edited February 7, 2022 by Eugene's DIY Den Talking Tools, a Facebook group for discussing anything tool/DIY related. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/44954-loop-resistance-for-non-eol-zone/#findComment-513687 Share on other sites More sharing options...
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