SuperlecDirect - ElectriciansForums.net Electrical Suppliers
This official sponsor may provide discounts for members

Discuss Earth fault loop impedance in the Electrical Forum area at ElectriciansForums.net

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

Morning all. So just trying to refresh my grey matter but having a biff moment. Earth fault loop impedance with circuits protected by BS EN60898 type B circuit breakers. I know the tabulated values are in table 41.3, but for the life of me I’ve forgotten how to calculate if acceptable or not. So for example; 40A circuit breaker, measured Zs 0.5, maximum tabulated value 1.09. How do I get the corrected values and see if acceptable? Any help for my non firing brain would be greatly appreciated. TIA.
 
Bulk Workwear - Clothing Suppliers for the Whole Forum Network
This official sponsor may provide discounts for members

Strima

-
Arms
Esteemed
As in multiply the tabulated by 0.8 to account for increased resistance on the cable under load conditions?
 

H

-
Arms
The values in table 41.3 BS7671 need to be multiplied as above (0.8), the values within the on site guide have already been adjusted to reflect the 0.8
 

telectrix

-
Mentor
Arms
Esteemed
and don't forget Cmin. that takes another 5% off the max. allowed value. however. I'm skeptical about the 0.8 correction esp. in a domestic. the 0.8 assumes that cables will be running @ 70 deg.C. that is loaded to the max. If you go with the design current Ib, rare you'll see cables getting that warm, only on things like showers.
 

Reply to Earth fault loop impedance in the Electrical Forum area at ElectriciansForums.net

uHeat Banner - Forum Discount Available
This official sponsor may provide discounts for members
Top Bottom