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Discuss r1 and r2 temperature calculations in the Periodic Inspection Reporting & Certification area at ElectriciansForums.net

M

maddfridge

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Hi all

just been going through max zs etc and all the temperature changes


if i have got this right when you measure for R1 and R2 you take the temperature at the time. Apply a rating factor to get it ot 20 degrees and then when calculating zs or what ever to get to 70 degrees multiply it by 1.2 ?

I think simply this is to ensure thermal constraints are being met

ideas please

doin me ead in need another beer :(

just wondered how many of you actual carry thermometers i got one cause i do fridge work as well
 
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E

ezzzekiel

  • Thread Starter Thread Starter
  • #2
use rule of thumb method - x 0.8
 
M

mouldy3

  • Thread Starter Thread Starter
  • #3
I agree with the above. You only calculate in temperature when designing the size of the cable before installation.
 
P

petewan

  • Thread Starter Thread Starter
  • #4
Table 2D, Appendix 2, on-site guide
 
F

fog

  • Thread Starter Thread Starter
  • #5
Hi all

just been going through max zs etc and all the temperature changes


if i have got this right when you measure for R1 and R2 you take the temperature at the time. Apply a rating factor to get it ot 20 degrees and then when calculating zs or what ever to get to 70 degrees multiply it by 1.2 ?

I think simply this is to ensure thermal constraints are being met

ideas please

doin me ead in need another beer :(

just wondered how many of you actual carry thermometers i got one cause i do fridge work as well
Hi i agree need senior members feedback, just had my assessment recently was asked a similar question about zs, figures referenced regs and gave the assessor the zs figure from the regs he was pleased that I had used the regs correctly and found the information and then reminded me that we should due to thermal effects use the 0.8, or 80% rule of thumb rule for the given zs. I then insisted that the regs was a horrifying document to follow and when we do find what we are after, its a complete load of bo**ocks as we anly use 80% of the given table obviously when the table was written most of us was going to put cables in only in arctic conditions, I don't think so! lets just make it more confusing. (my assessor did not wish to comment but he was helpful on many other questions.)
 

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