Discussion in 'New Member Introductions' started by Tony Ryan, Feb 25, 2017.
Discuss Newly Qualified to domestic level in the New Member Introductions area at ElectrciansForums.co.uk.
Hi am Tony newly qualified Domestic installer just thought i would say hello really.
Welcome to the forum Tony
Hi Tony best of luck with your work.
Welcome to the forums
A Question i have newly installed a Radial citcuit for a shower i have used a 10mm t&E cable about a 20 metre run when completing the continuity test of cpc i a m receiving a 0.21 Ohms reading the metrel tester i am using is showing up a red X on the display screen any ideas ?
I would say that's a bit high. Based on the figures in GN3 for resistance of a 4mm core (I'm assuming it's a 4mm cpc), I get around 0.09 (4.61mOhms/m x 20). As for the red X, never used a Metrel, time for the user manual I think.
Thanks for the info sparkychic will re-doing the cpc check again just seems very strange to receive a reading like that hopefully will get a diff outcome later on.
Is this a test of R2 or R1+R2 ? tabulated values for R1+R2 for 10mm/4mm t&e should be about 0.13 at 20m.
High resistance connections, anomolies in test leads, low batteries in tester etc could all be contributing to a high reading.
First check the manual to find out what the red X means, you should reject the measurement until you have got past this potential issue with the equipment.
Have you nulled the leads correctly? Did you have good contact pressure on the probes?
Did you consider the accuracy of the tester?
Are the batteries in the tester fresh?
Have looked at the metre still having issues with the red x on display it is a test of r1+r2 charged up batteries this morn still having issues tho.
Which Metrel model do you have?
Well in that case, if it's R1+R2 for a 10/4 T+E, it's 6.44mOhms/m according to GN3 and you should be expecting something in the region of 0.13ohms.
Having just had a quick skim of a Metrel manual (for the EuroTestXC), a big red X implies the test results are outside of a configured acceptable range. If it's 'Cal X', then the lead resistance hasn't been compensated for.
did you null the leads
Need to spk with someone i re did the shower r1 r2 test got 0.01 ohms to begin with and got a green X then trying it again i jave gone straight bk to a red X wracking my brains on this one very strange have nulled the leads but getting very mad results lol
As been advised, check connections, check batteries. Unless the testers u/s, you should get the same (or very similar) test results.
Plus not knowing the meter (but think I understand the concept), 0.01 ohms gets a green X pass but the readings too low and 0.21 ohms gets a red X, fail on both counts.
With metrel you can set a fail level for continuity. On mine it's default is 2 ohms. Often get a red X when testing continuity of long lighting runs but that's just because I can't be bothered to adjust the limit. I don't look at the X, it's meaningless so long as you know what figures you should be looking for
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