Earth Bond Test, Question.

PATGuard 3 Forum

Earth Bond Test, Question.

Postby Ford Prefect » Thu Jan 22, 2015 10:21 am

I wonder if anyone can help.
We have a piece of equipment that I (more properly the Apollo 600 ) have failed on the earth bond test.
When it went for repair/re-wire the person who was going to repair it also tested it and passed it! I have found out he was basing his pass on a 0.2 Ohm base before allowing for cable, however according to the CoP it should be (0.1 + R) Ohm, as the unit is fed from a timer box via a 5 core cable would the 0.2 be more correct?
Any input would be greatly appreciated.
User avatar
Ford Prefect
 
Posts: 43
Joined: Wed Dec 17, 2014 9:50 am
Location: Portsmouth

Re: Earth Bond Test, Question.

Postby Stephen Armstrong » Fri Jan 23, 2015 3:28 pm

Thank you for your enquiry

Please get your copy of our Guide to PAT, at the following link:

http://www.seaward.co.uk/userfiles/pat-testing-guide.php

Please see page 14 of the above guide, (0.1 + R) Ohms is the correct equation. However, you need to know the csa and multiply this by the length of the cable (page 22) to calculate the correct value of R. Then add this value to 0.1 to determine the total resistance.

And also please see:

http://www.seaward.co.uk/downloads/3584_pat_posters_2011_layout_2_v2.pdf

Kind regards
Technical Support
Stephen Armstrong
Technical Sales Engineer
 
Posts: 49
Joined: Fri Jul 05, 2013 8:35 am

Re: Earth Bond Test, Question.

Postby Ford Prefect » Fri Jan 23, 2015 4:45 pm

Thanks for that.
So yes I was right as I am basing it on (0.1 + R) Ohms and adjusting (using the calculator on the 600) for csa and length as in the CoP.
The repairer (who has been PAT testing for years) was however starting at (0.2 + R) Ohms before adjusting for csa and length!
My question was as the unit is fed from a timer box via a 5 core cable would the 0.2 be more correct? meaning, was there another way of say adjusting for what must be extra circuitry in the box, as the repairer is a seasoned PAT tester I thought he might know something I don't that someone more experienced on this forum might be able to help with.
User avatar
Ford Prefect
 
Posts: 43
Joined: Wed Dec 17, 2014 9:50 am
Location: Portsmouth

Re: Earth Bond Test, Question.

Postby Grizzly » Mon Jan 26, 2015 1:56 pm

Nah, the repairer is using the wrong pass limits, as can be shown from all the guidance literature available.
Maybe ask him to give his reasoning as to why he sets his pass limit at (0.2 + R)Ω rather than (0.1 + R)Ω.
I may be cynical, but I'll bet he does it so he has fewer failures, and so fewer issues to diagnose...
C&G 2377 -01 & -02
User avatar
Grizzly
 
Posts: 114
Joined: Tue Feb 08, 2011 3:27 pm

Re: Earth Bond Test, Question.

Postby Ford Prefect » Mon Jan 26, 2015 2:25 pm

Cheers Grizzly,
That was my reasoning but as I've only been doing this for just over a year and he's been doing it ages I wanted to check.The only way I worked it out I'd be able to pass it was if it was a 4m, 3A cable which it hasn't got!
Thanks Again.
User avatar
Ford Prefect
 
Posts: 43
Joined: Wed Dec 17, 2014 9:50 am
Location: Portsmouth


Return to Portable Appliance Testing


Who is online

Users browsing this forum: Bing [Bot], Yahoo [Bot] and 1 guest

 
 
cron