G
Gardner
Under BS7671, what is the amperage of 1.5mm2, 2.5mm2 and 4mm2 copper conductor restricted to when inside a race way or cable of no more than 3 current carry conductors? Thank you! :smiley2:
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Discuss mm2 ampacity restrictions in the UK Electrical Forum area at ElectriciansForums.net
got the earth loop tester i ordered
it arrived a full week ahead of schedule
the thing is a bit of a beast! came in a handsome case with heavy short and long leads (with rather stout clips on them)
2 earth spikes and manual(chinese manual, but manufacturer included a link to download it in english)
Ill post pics as soon as i can.
taking the time to read the manual right now
efli is bassically checking the resistance L-E at the supply through the supply transformer to its star point then through the return earth path to make sure it complies to the max values in the iee wiring regs.
each mcb/fuse etc has a max zs, if it doesnt comply then a different type or a bigger cable is required
Earth fault loop impedance testing is basically to confirm or otherwise that a sufficient low impedance exists to cause the operation of the protective device, within the required time anywhere on the circuit under test. eg Zs
Earth Loop testing at the origin of the supply ''Ze'' will confirm if any earthing exists and will give a value for that earth. An earth loop tester will also give the PEFC and PSCC at the origin of the installation....
I'm sure others here will give you a more in-depth explanation... lol!!
Your views on Stateside electrical testing seems to be held by another American Electrician on the forum, ''Gnuuser'' from NW Pa who has recently purchased his own Earth Loop Tester. Though i've never seen a loop tester come with earth spikes, so it must be a Chinese multi function bit of kit.
Check out the forum test meter sponsor (test-meter.co.uk) to check out the typical loop testers that are commonly used in the UK and EU....
He did the right thing! Tell him he is steps ahead already. A megger would also compliment is earth loop tester very well.
Tell him yourself, he is a member here just like yourself!! lol!!
As for your take on ELI testers, and the principles of how they work are to be honest a little flawed, but i'm sure someone here will explain them for you, (or you can wait until i have enough time to do so). Right now, i'm trying to do too many things, plus getting ready for the students i tutor coming to site tomorrow morning. ...Bang goes my Saturday off this weekend!!
It depends what supply is available where they are parked up. No problem with having a TT earthing system, providing adequate protection is provided. TNC-S isn't recommended if the trailer has an overall outer metal skin as part of it's construction...
Any chance of posting a few photo's of these trailers your company produces?? What sort of function do they fulfil, (eg, temporary site offices/workshop, residential)
These are primarily work trailers. Id have to ask if its ok to post any pics.
My understanding is that if TT is used (Correct me if I am wrong) its not involved with pin and sleeve connections. In any cases, a TT network would need a local earth electrode. The main breaker is recommended that it be a 100ma delayed RCD, while the branch breakers are RCBOs 30ma. The dual RCD in series in the event one fails another can back this up?
In fact, when AFCIs (Arc Fault Circuit Interrupters) were required for general use residential circuits a few years back, the ones that had 30ma differential protection caught a lot of wiring errors. Complaints were and are still common of them tripping on new home construction. Turns out electricians were making tons accidental neutral to ground and crossing neutrals between circuits... all code violations that testing would have caught. Without a doubt older installations before the AFCI requirements have boat loads neutral to earth faults. I have seen it first hand.
Unless something has radically changed with these AFCI's it was proved over and over again by some prominent US Electrical Engineers they just didn't work as claimed. This was proven many times by independent test labs, none ever managed to get any of these breakers to trip when subjected to a series arc fault or a full on sustained arch fault. You i think mentioned Mike Holt, who also undertook to test these breakers, and again couldn't get any of the breakers to perform as claimed by the manufacturers... There still isn't (to my knowledge) a commercially available means to test these breakers (eg, ...AFCI test kit/meter) the only way to get these breakers to trip, is pressing the blue test button on the breaker !!
So what's your take on these breakers whether including a GFCI element or not??
As far as i'm aware, these AFCI breakers are not requirement in the UK/EU, to be honest i'm not even sure they are available/stocked this side of the big pond. Personally i've only seen mentions of these devices in manufactures catalogues, but without showing the usual data and specifications...
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