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Rfc Lenghth As Per Resistance Value
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<blockquote data-quote="SPECIAL LOCATION" data-source="post: 307433" data-attributes="member: 250"><p>Your calculations appear correct to me...</p><p></p><p>Assumed lengths of individual conductors from your values of readings should be within a gnats whisker of each other, as they are all in the same cables...</p><p></p><p>Your total length of individual conductors are:-</p><p></p><p>r1 = 191.6m </p><p></p><p>r2 = 192.6m if @ 1.5mm</p><p></p><p>rn = 190.3m </p><p></p><p>average length 191.5m</p><p></p><p>So assuming you got the best part of 200m of cable making up this ring...</p><p></p><p>What floor area is it covering??</p><p></p><p>I would guess its a bit bigger than the rule of thumb max 100m2 as per appending 14?</p><p></p><p>R1+R2 0.98... is that a measured value?</p><p></p><p>it's not far off the calculated value 1.42+2.33/4 = 0.9375</p><p></p><p>Whats your Ze? and what type of MCB is on the circuit?</p><p></p><p>32A B Max Zs is 1.44 @ 80% is 1.15..</p><p></p><p>1.152 - your 0.98 only leaves 0.172ohms worth of Ze till you are getting high on your Zs.</p><p></p><p></p><p></p><p>19.51 is the miliohms per meter of a single piece of 2.5mm T&amp;E..</p><p></p><p>if on a ring, 2 x 2.5mm are in parrallel...</p><p></p><p>so miliohms per meter would be 19.51/2 = 9.755..</p><p></p><p>so</p><p></p><p>BES's (0.98 / 9.755)x1000 = 100.46m from CU to furthest point ..</p><p></p><p>which is in keeping with his 190+m worth of cable used.. </p><p></p><p>My gut feeling this circuit is feeding a bit to large an area.</p></blockquote><p></p>
[QUOTE="SPECIAL LOCATION, post: 307433, member: 250"] Your calculations appear correct to me... Assumed lengths of individual conductors from your values of readings should be within a gnats whisker of each other, as they are all in the same cables... Your total length of individual conductors are:- r1 = 191.6m r2 = 192.6m if @ 1.5mm rn = 190.3m average length 191.5m So assuming you got the best part of 200m of cable making up this ring... What floor area is it covering?? I would guess its a bit bigger than the rule of thumb max 100m2 as per appending 14? R1+R2 0.98... is that a measured value? it's not far off the calculated value 1.42+2.33/4 = 0.9375 Whats your Ze? and what type of MCB is on the circuit? 32A B Max Zs is 1.44 @ 80% is 1.15.. 1.152 - your 0.98 only leaves 0.172ohms worth of Ze till you are getting high on your Zs. 19.51 is the miliohms per meter of a single piece of 2.5mm T&E.. if on a ring, 2 x 2.5mm are in parrallel... so miliohms per meter would be 19.51/2 = 9.755.. so BES's (0.98 / 9.755)x1000 = 100.46m from CU to furthest point .. which is in keeping with his 190+m worth of cable used.. My gut feeling this circuit is feeding a bit to large an area. [/QUOTE]
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