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Topic Title: old t&e using only one core and earth -induced currents
Topic Summary: previous threads on 'connecting the unused core'
Created On: 05 September 2013 08:38 AM
Status: Post and Reply
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 05 September 2013 08:38 AM
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psychicwarrior

Posts: 220
Joined: 18 October 2010

re: t&e using one core and cpc on lighting

i've always thought it was poor to see t&e used where the neutral was cut off - looks 'unfinished' if you like - but have not noticed any Reg. to say its a no-no , or what to do with the unused core.

good practice says terminate it if you do it and i suggest that's to stop a 'loose' unconnected conductor being live should a fault occur.

excuse me for my lack of [fully understanding] magnetism , but at what level of [high] normal and/or fault current would induce a current (if at all) into the other core(s) in such a live conductor run with earth ?
 05 September 2013 08:47 AM
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davezawadi

Posts: 2639
Joined: 26 June 2002

This is not a significant problem. The induced power will be tiny as there is no magnetic core, and at 50Hz there is nearly zero coupling (very high transfer impedance). The best thing to do is terminate the unused core in choc blocks so that it could be used later.

-------------------------
David
CEng etc, don't ask, its a result not a question!
 05 September 2013 09:14 AM
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psychicwarrior

Posts: 220
Joined: 18 October 2010

@david 'the wizard'

thanks for the comments. as an aside and in being a musician (allegedly) who has suffered many a poor sound engineering experience, i did visit your 'myurl' and was intrigued by the contents :-)

what came first in terms of interest - the electrical or the sound and ...... if you were to pick one key fundamental technical principle that has most impact and that links the two.....what would it be ?


thanks again
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