This official sponsor may provide discounts for members

# r1 and r2 temperature calculations

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

M

Welcome to ElectriciansForums.net - The American Electrical Advice Forum
Head straight to the main forums to chat by click here:  American Electrical Advice Forum

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

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

Last edited by a moderator:
This official sponsor may provide discounts for members
E

#### ezzzekiel

use rule of thumb method - x 0.8

M

#### mouldy3

I agree with the above. You only calculate in temperature when designing the size of the cable before installation.

P

#### petewan

Table 2D, Appendix 2, on-site guide

F

#### fog

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

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.)

This official sponsor may provide discounts for members