max measured earth loop impedance query

[Silo]

Hi guys,
Im just filling in my first ever solo EIC when I check the onsite guide and gn3 for max permitted zs (tabulated) for bs60898 type b 32A the table shows 1.16ohms but to me it didnt ring a bell, checking bs7671 table 41.3 shows max zs to be 1.44.

Can anyone shed some light on why and which I should use as the tabulated value?

Regards,
Simon

 

[Billythekid]

Your answer is within the books that you mention.

 

[tony mc]

BS 7671 give max ZS and OSG & GN3 give the ZS with correction factors included did you not cover the 0.8 rule of thumb method !

 

[Silo]

Errr.....doh! Cheers Tony, yes I did but at 7.30 this morning it didn't even spring to mind.

Thanks again!

 

[telectrix]

the osg figures allow for resistance increase of cable when operating at a higher temperature. i.e.70deg. as opposed to the 20deg. that you are measuring at. as the sotr asks for the max. figure, i always use the bgb values. never yet seen a cable running at 70deg. under normal conditions except on some industrial applications.

 

[Silo]

Telectrix, where im working right now its 8 degrees inside! I wouldnt mind a bit of 20 degs hete

 

[telectrix]

have to work a bit faster then.

 

[Silo]

Thanks for the support! :-(

 

[telectrix]

i did 6 months 500ft. down the salt mine. it was a constant 10deg. summer and winter. working in tee shirt. best thing was... it never rained.

 

[Silo]

Lol I'd hate to be there and think " bugger" left something in the van!

 

[telectrix]

haha. took 45 minutes to get out to the van and back. deliberately left something behind as it was a perfect excuse to get out and have a smoke. boss got wise after a while and decreed that anything i was short of, i'd have to do without till break time. bugger.

 

[Knobhead]

You would think with a salt mine everything would be red rusty, not a bit of it, the air’s to dry.

Did you see the grave yard? All the machines taken down there, worked to death and then just dumped in a corner.

 

[telectrix]

everything did go rusty. we were using 10 cans of wD40 a week, spraying tools.