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Student & Learning Zone - City & Guilds
Testing final ring
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<blockquote data-quote="SPECIAL LOCATION" data-source="post: 500686" data-attributes="member: 250"><p>Just as a side thought, in case you are not aware...</p><p></p><p>Just because a ring has one (or more) spurs off it...</p><p></p><p>The furthest point (highest Zs) can still be a socket directly connected to the ring.. not always at a spur..</p><p></p><p>e.g.</p><p></p><p>Imagine a ring with 5 sockets equally spaced 10m apart.. </p><p></p><p>The middle ring socket will have two parallel paths equal to the resistance of 15m worth of cable.. (2x 30m in parallel).</p><p></p><p>And either of the sockets nearest the supply will have parallel paths via a 10m &amp; 50m cable run..</p><p></p><p>So resistance will be less than the value of 10m worth of cable due to parallel effect.</p><p></p><p>If this socket has a spur with 3m of cable the R1+R2 (&amp; Zs)</p><p></p><p>will be proportional to less than 13m worth of cable resistance..</p><p></p><p>i.e. The spur will have a lower Zs than the middle socket directly connected to the ring.</p><p></p><p>Whilst this may have no relevance to your particular question in hand..</p><p></p><p>It may be worth remembering so you don't go making any wrong assumptions in the future.</p><p></p><p> Guinness</p></blockquote><p></p>
[QUOTE="SPECIAL LOCATION, post: 500686, member: 250"] Just as a side thought, in case you are not aware... Just because a ring has one (or more) spurs off it... The furthest point (highest Zs) can still be a socket directly connected to the ring.. not always at a spur.. e.g. Imagine a ring with 5 sockets equally spaced 10m apart.. The middle ring socket will have two parallel paths equal to the resistance of 15m worth of cable.. (2x 30m in parallel). And either of the sockets nearest the supply will have parallel paths via a 10m & 50m cable run.. So resistance will be less than the value of 10m worth of cable due to parallel effect. If this socket has a spur with 3m of cable the R1+R2 (& Zs) will be proportional to less than 13m worth of cable resistance.. i.e. The spur will have a lower Zs than the middle socket directly connected to the ring. Whilst this may have no relevance to your particular question in hand.. It may be worth remembering so you don't go making any wrong assumptions in the future. Guinness [/QUOTE]
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Testing final ring
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