Guest Posted March 19, 2005 Share Posted March 19, 2005 Where does that leave single core phone cable then....The debate goes on, we have people coming on here asking if they can wire an alarm with phone cable. For the cost of the alarm cable, I cant understand why you want to redesign something that aint broke - i.e. if it aint broke dont fix it. 44848[/snapback] it leaves single strand CAT3 to coldshire then.. ofcourse people CAN wire with whatever they find but if it is against reg's and common practise there it isn't quite a good idea. I ordered 100m of UK alarm cable and found it to be good for DC-loop systems especially because that manufacturer had two thicker cores for pwering detectors etc.. i would be interested thou what is capasitance between cores in UK alarm cable. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-44853 Share on other sites More sharing options...
Guest Posted March 19, 2005 Share Posted March 19, 2005 So can we use wet string? Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-44855 Share on other sites More sharing options...
Guest Posted March 19, 2005 Share Posted March 19, 2005 So can we use wet string? 44855[/snapback] I have heard that UK is situated in a rainy island so why not?? Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-44863 Share on other sites More sharing options...
Guest Posted March 19, 2005 Share Posted March 19, 2005 I have heard that UK is situated in a rainy island so why not?? 44863[/snapback] Georg - you are silly at times! - its because it has to be insulated wet string of course! Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-44867 Share on other sites More sharing options...
Guest Posted March 19, 2005 Share Posted March 19, 2005 Georg - you are silly at times! - its because it has to be insulated wet string of course! 44867[/snapback] maybe isolated as well..? Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-44870 Share on other sites More sharing options...
breff Posted March 19, 2005 Share Posted March 19, 2005 Georg, I dont know what the capacitance is , but you probably know how to work it out. The NVP of alarm cable is 57% where as Cat5 is 67%. Thats all I know. And to the original poster, just use normal 8 core 7/.22 alarm cable. The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not) Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-45006 Share on other sites More sharing options...
Guest Posted March 20, 2005 Share Posted March 20, 2005 Georg, I dont know what the capacitance is , but you probably know how to work it out.The NVP of alarm cable is 57% where as Cat5 is 67%. Thats all I know. And to the original poster, just use normal 8 core 7/.22 alarm cable. 45006[/snapback] NVP? (Non Volatile Polarity ... ) Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-45045 Share on other sites More sharing options...
breff Posted March 20, 2005 Share Posted March 20, 2005 Look Here.... http://www.nordx.com/public/htmen/Tech_Tip_3.htm Apparently Capacitance is directly proportionate to NVP but I dont know the formula. The opinions I express are mine and are usually correct! (Except when I'm wrong)(which I'm not) Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-45049 Share on other sites More sharing options...
bellman Posted March 21, 2005 Share Posted March 21, 2005 blic/htmen/Tech_Tip_3.htm[/url]Apparently Capacitance is directly proportionate to NVP but I dont know the formula. 45049[/snapback] From the web:- Nominal Velocity of Propagation (NVP) In a conductor, electrons travel at near the speed of light. For a copper cable this speed is often expressed as a decimal fraction of the speed of light. (UTP has an NVP of about 0.59-0.65).. The lower the NVP, the greater the delay in signals reaching a destination, so a high NVP is required for a good quality cable. I don't know the formula either breff, I'll have a good google for it later. Regards Bellman Service Engineer and all round nice bloke ) The views above are mine and NOT those of my employer. Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-45070 Share on other sites More sharing options...
Guest Posted March 22, 2005 Share Posted March 22, 2005 Oh, ok. NVP with cables where the conduit is copper is approximately 130 meters in a microsecond (regarding the cable as mentioned above). But capasitance depends also of cable lenght and is usually announced as pF / 1km . Link to comment https://www.thesecurityinstaller.co.uk/community/topic/5462-alarm-installation-cable-type-query/page/5/#findComment-45208 Share on other sites More sharing options...
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