JIMBOY Posted June 8 Share Posted June 8 Hi I installed a optima G4 in place of existing faulty alarm. As it was only a basic system I upgraded the system by installing additional PIRs. The PIrs are honeywell Activ8 and have a internal built in resistance on the alarm contacts of 17 ohms giving approx 20 Ohms on the loop. Also I installed 2 PIrs in series for zone 2 to allow entry/exit inhibit for front door and side door, this doubling the loop to 39 Ohms. The manual does not mention zone resistance and the diagrams just show N/C contacts. Is there a max resistance on the input zones? Door entry and window contacts are just a few ohms wire resistance. Quote Link to comment Share on other sites More sharing options...
PeterJames Posted June 8 Share Posted June 8 Wouldn't recommend pirs in series, after a fa how do you know which one went off ? Quote Link to comment Share on other sites More sharing options...
james.wilson Posted June 8 Share Posted June 8 agreed. It will work like driving with no windscreen but its not best. If you need more circuits use a bigger panel Quote securitywarehouse https://store.securitywarehouse.co.uk Trade Members please contact us for your TSI vetted trade discount. Link to comment Share on other sites More sharing options...
sixwheeledbeast Posted June 9 Share Posted June 9 There will be a resistance threshold for closed loops but the lower the better, usually it's around 100-200 which you don't want to be near, but will vary on panel. Issue is diagnosing future issues when you have multiple devices on a circuit, as above. Quote Link to comment Share on other sites More sharing options...
JIMBOY Posted June 10 Author Share Posted June 10 Thanks for the replies, i know it was not ideal using 2x pirs in series. But I can free up a zone (Window contacts) and connect PIR in that room in series with the window contact, therefore ie zone 4 PIR+ window contact . That would allow the entry/exit zones to have their individual PIR (Timed). I was more concerned about the loop resistance. All loops then would be in the 20-22 Ohm range, except for door entry Quote Link to comment Share on other sites More sharing options...
sixwheeledbeast Posted June 10 Share Posted June 10 If there aren't enough zones it needs a bigger panel. 2 Quote Link to comment Share on other sites More sharing options...
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