Question 1

Where BS 7671 show a protective device as having a maximum Zs value of 2.3O the maximum corrected value will be

Accepted Answer

A)  2.3â„¦ 
B)  1.84â„¦ 
C)  1.72â„¦ 
D)  2.87â„¦ 
A)  2.3â„¦ 
B)  1.84â„¦ 
C)  1.72â„¦ 
D)  2.87â„¦ B

Question 2

The maximum tabulated Zs for a protective device as shown in BS 7671 is 1.44â„¦, the maximum permissible measured Zs will be

Accepted Answer

A)  1.44â„¦ 
B)  1.43â„¦ 
C)  1.15â„¦ 
D)  1.08â„¦ 
A)  1.44â„¦ 
B)  1.43â„¦ 
C)  1.15â„¦ 
D)  1.08â„¦ C

Question 3

The stated maximum Ze for a TN-S supply system is

Accepted Answer

A)  0.35Ω 
B)  0.21Ω 
C)  0.8Ω 
D)  0.85Ω 
A)  0.35Ω 
B)  0.21Ω 
C)  0.8Ω 
D)  0.85Ω C

Where BS 7671 show a protective device as having a maximum Zs value of 2.3O the maximum corrected value will be

The maximum tabulated Zs for a protective device as shown in BS 7671 is 1.44â„¦, the maximum permissible measured Zs will be