F
Flakey
Hi i was looking at this old post and saw a calculation resolved which im not too sure is right and would apprciate confirmation wether it is or isnt
Q24. A continuity of ring final circuit conductors test is to be carried out on a circuit supplying the office. The circuit is wired in 2.5mm cable with 1.5mm cpc. The loop length of the cable is 65m. All socket outlets are connected directly on the ring. Explain in detail, using the information given in figure 1, the three steps required to confirm the continuity of this circuit.
Your explanation should include the
. test instrument
. test connections and the expected readings at each stage
Show all calculations
A24. The test instrument used is a low resistance ohm meter. First test is an end to end of the line neutral and cpc of the ring. This is confirm all conductors form a complete ring. The expected results are:
Line – line – 2.5mm cable = 7.41 mohm/m
(7.41x65)/1000 = 0.48 ohms
Neutral – Neutral – Same as above
Cpc – Cpc – 1.5mm = 12.1 mohms/m
(12.1x65)/1000 = 0.786 ohms
Next cross connect line and neutral of the ring L1 + N2 and L2 +N1 and test at all socket outlets
Expected readings:
R1+Rn = (r1+rn)/4 = (0.48+0.48)/4 = (0.24) ohm Do you use this figure in the stage 3 part of the calculation (0.24)
Next cross connect line and cpc L1 + cpc2 and L2 + cpc1 and test at all socket outlets
Expected readings:
R1+R2 = (r1+r2)/4 = (0.48+0.786)/4 = 0.32 ohms so 0.24 + 0.786/4 = 0.25 ohm ? or do you use (0.48+0.786)/4 = 0.32
Many thanks
James
Read more: http://www.electriciansforums.net/e...1-2391-theory-test-paper-3.html#ixzz2EGbEuDX6
Q24. A continuity of ring final circuit conductors test is to be carried out on a circuit supplying the office. The circuit is wired in 2.5mm cable with 1.5mm cpc. The loop length of the cable is 65m. All socket outlets are connected directly on the ring. Explain in detail, using the information given in figure 1, the three steps required to confirm the continuity of this circuit.
Your explanation should include the
. test instrument
. test connections and the expected readings at each stage
Show all calculations
A24. The test instrument used is a low resistance ohm meter. First test is an end to end of the line neutral and cpc of the ring. This is confirm all conductors form a complete ring. The expected results are:
Line – line – 2.5mm cable = 7.41 mohm/m
(7.41x65)/1000 = 0.48 ohms
Neutral – Neutral – Same as above
Cpc – Cpc – 1.5mm = 12.1 mohms/m
(12.1x65)/1000 = 0.786 ohms
Next cross connect line and neutral of the ring L1 + N2 and L2 +N1 and test at all socket outlets
Expected readings:
R1+Rn = (r1+rn)/4 = (0.48+0.48)/4 = (0.24) ohm Do you use this figure in the stage 3 part of the calculation (0.24)
Next cross connect line and cpc L1 + cpc2 and L2 + cpc1 and test at all socket outlets
Expected readings:
R1+R2 = (r1+r2)/4 = (0.48+0.786)/4 = 0.32 ohms so 0.24 + 0.786/4 = 0.25 ohm ? or do you use (0.48+0.786)/4 = 0.32
Many thanks
James
Read more: http://www.electriciansforums.net/e...1-2391-theory-test-paper-3.html#ixzz2EGbEuDX6
