It might help if you could provide the question in full detail?
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It might help if you could provide the question in full detail?
Hi Pushrod,
I see what your thinking but its on an old 2391 test paper,it gives you a Sched of Test Result sheet with a lighting circuit of 45 n long and an R1 +R2 reding of 0.52 , which must be the dead test reading. The Q. asks you to calculate the maximum expected test result value for the info given in a table showing 1.5 mm cable ,with 12.1 mohms/m value at ambient temp of 20 degrees.
To me its just asking for a like for like value of R1 +R2 cold , not any 1.2 con oper temps etc, so why should the dead test reading be more then the calc value , im confused
Regards
Locket
Hi Pushrod,
Ithink you might have nailed it, sorry i havnt given the full drawn scenario , but it does say in the workshops the single cables are run in surface mounted steel conduit and trunking, so bearing this in mind ,my question to you is,when doing a dead test R1+R2 with the standard low ohm meter, would you still get parrell paths effecting the reading as you think above giving you a lower reading?
Regards
When we do R1+R2 test at college we use a crocodile clip attaching say the appropriate line cable connected with the clip on one end to the cpc busbar (not disconnected appriopriate cpc) but even then where would the parrell paths be even doing it this way ,i dont understand.
locket
Have you asked your tutor why?
Just think about it. by clipping direct onto the earth bar you are connecting to all the other CPC's on that board. If that Earth bar is the installations MET, then you will also have the bonding conductors to the services, may not be gas but certainly water, that will also be on there, so you have all those parallel paths.
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