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 Topic Title: Zs on a single circuit Topic Summary: How do i measure the Zs of a single circuit. Created On: 01 February 2013 01:57 PM Status: Read Only Linear : Threading : Single : Branch
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 01 February 2013 01:57 PM JBrown123 Posts: 1 Joined: 01 February 2013 Can anyone please explain to me how to measure the Zs of a single lighting circuit ? not the whole installation. thanks! 01 February 2013 02:21 PM OMS Posts: 22435 Joined: 23 March 2004 Find the end (or worst favoured branch) and measure from there if you want a live test direct reading with a EFLI tester Or do the same by measuring the relevent phase and CPC dc resistance and calculate it with knowledge of the impedance external to the installation. Or calculate it from knowledge of the cable size and length and again with knowledge of the external impedance. Regards OMS ------------------------- Let the wind blow you, across a big floor. 01 February 2013 06:00 PM dg66 Posts: 1712 Joined: 11 January 2008 The third option mentioned by OMS should be used in combination with either of the other two options mentioned. ------------------------- RegardsDave(not Cockburn) 01 February 2013 06:22 PM Zs Posts: 3830 Joined: 20 July 2006 Wow. 01 February 2013 06:29 PM Jaymack Posts: 5380 Joined: 07 April 2004 Originally posted by: JBrown123 Can anyone please explain to me how to measure the Zs of a single lighting circuit ? Measure R2 at light switches and at lighting points, to determine the worst case for the circuit, take this highest value and either test there for Zs or use in the calculation. Regards 01 February 2013 06:45 PM daveparry1 Posts: 7749 Joined: 04 July 2007 I don't quite know why you need to measure the Zs if you dont know how to do it? What i'm trying to say is that a Zs figure is only normaly used by an electrician to check the safety of a circuit! Dave. 01 February 2013 11:14 PM Martynduerden Posts: 3235 Joined: 13 July 2008 Originally posted by: Zs Wow. Good init! ------------------------- RegardsMartyn.Only a mediocre person is always at their best 01 February 2013 11:33 PM John Peckham Posts: 8793 Joined: 23 April 2005 JBrown123 Welcome to the forum. Is this a test question you have been asked to answer by your college lecturer for Monday morning? If so we may need to give you a different answer to stop you falling in to an evil trap set by a wicked person. Lecturers of course don't live in the real world but some sort of academic lah lah land! Dooh I might have just shot myself in the foot. ------------------------- John Peckhamhttp://www.astutetechnicalservices.co.uk/ 02 February 2013 07:26 PM AJJewsbury Posts: 16113 Joined: 13 August 2003 Measure R2 at light switches and at lighting points, to determine the worst case for the circuit Presuming L follows the same route as PE ... which isn't necessarily the case for a lighting circuit - Andy. 04 February 2013 01:19 PM BigRed Posts: 580 Joined: 10 November 2006 measure Zs? with a tape measure...:-) Gives me the distance to avoid the curled up hand hurtling towards my arm..... 04 February 2013 03:17 PM zeeper Posts: 1504 Joined: 11 July 2008 measuring the relevent phase and CPC dc resistance and calculate it Hes just lost three points for calling the line conductor a phase conductor.
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