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Topic Title: Cable bedding
Topic Summary: Effects on rating
Created On: 20 September 2017 12:41 PM
Status: Read Only
Linear : Threading : Single : Branch
 Cable bedding   - jammyc - 20 September 2017 12:41 PM  
 Cable bedding   - mapj1 - 20 September 2017 01:28 PM  
 Cable bedding   - jammyc - 20 September 2017 02:10 PM  
 Cable bedding   - mapj1 - 20 September 2017 11:26 PM  
 Cable bedding   - jammyc - 21 September 2017 02:35 PM  
 Cable bedding   - mapj1 - 21 September 2017 10:40 PM  
 Cable bedding   - OMS - 23 September 2017 08:50 AM  
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 20 September 2017 12:41 PM
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jammyc

Posts: 31
Joined: 25 November 2009

Hi,

How deep a bedding and blinding layer should be allowed before it's used instead of the native soil for the thermal resistivity?

I not managed to find an answer in reference books so I've been conservative on this in the past (i.e. if sand has been used, of any depth, then for calcs assume well-drained sand @ 2.5Km/W). Obviously this depends on the backfill.

I've compared results with some IEC-method tools and it seems to support my conservative approach but but I wonder if that's overkill in reality (since moisture retained in native clay would probably stop a few cm of sand drying out so quickly) and I can use smaller conductors / more bedding / less CBS. Which would be nice, but I'd like to have something to point at to back it up.

J
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