Zs adjustment

[KAS1]

When measuring Zs values, does everyone apply the correction factors for temperature during fault conditions to the value?

 

[monkeyelectric]

I generally use the 80% figures unless the reading is of the higher end of the figures

 

[Guest154]

the 0.8 value is to be applied to the bs7671 values not the measured value

 

[Guest55]

no corrections are made to any measurement , record as seen.

 

[monkeyelectric]

the 0.8 value is to be applied to the bs7671 values not the measured value

The 80% values are in the osg

 

[telectrix]

the max. figure is, IMO, that given in BS7671., not some guesstimate of 0.8x because of a non-specified guessed temperature the cable might be at.

 

[KAS1]

Yes but I think he meant he'd apply this 0.8 to the max Zs allowed and then compare his measured Zs against the new lower figure, well I hope he did

the 0.8 value is to be applied to the bs7671 values not the measured value

 

[Guest154]

no u times the regs values by 0.8 and the ones in the OSG have already been corrected

 

[Guest154]

kas1 u r correct

 

[monkeyelectric]

no u times the regs values by 0.8 and the ones in the OSG have already been corrected

0.8 and 80% are the same thing surely? I meant i would measure zs of a circuit, take the maximum value and if its below the osg value then great there's room for manouver but of course the maximum values are in the bgb so as long as its below that its fine

 

[telectrix]

0.8 and 80% are the same thing surely? I meant i would measure zs of a circuit, take the maximum value and if its below the osg value then great there's room for manouver but of course the maximum values are in the bgb so as long as its below that its fine

my thoughts exactly

 

[Guest154]

yeah ignore me i read the first post wrong

 

[Risteard]

0.8 and 80% are the same thing surely? I meant i would measure zs of a circuit, take the maximum value and if its below the osg value then great there's room for manouver but of course the maximum values are in the bgb so as long as its below that its fine

Those figures are for the Designer. The Inspector should ensure that the measured value does not exceed the corrected value.

 

[monkeyelectric]

Those figures are for the Designer. The Inspector should ensure that the measured value does not exceed the corrected value.

Read what i've written! I've said its great if they're below the 80% but fine if they're below the bgb values!

 

[johnboy6083]

If the circuit has already been energised, and has been at full operating temp, then you can use the max values in BS7671.
for an initial verification you should apply the rule of thumb (x 0.8) this is to allow for the increase of resistance as the circuit warms up.