04: 41 Protection Against Electric Shock (55) Flashcards
When automatic disconnection of supply is used as a measure of protection, additional protection by RCD shall be provided for (411.3.3 p.59)
a) Mobile equipment having a rating of greater than 32A
b) Socket outlets in commercial and industrial locations
c) Only for sockets rated at 32A or less where it is reasonable to expect they may be used to supply equipment for use outdoors
d) Socket-outlets with a rated current not exceeding 32A
d) Socket-outlets with a rated current not exceeding 32A
411.3.3 p.59
In AC systems, additional protection by means of an RCD with a rated residual operating current not exceeding 30 mA shall be provided for:
(i) socket-outlets with a rated current not exceeding 32A, and
(ii) mobile equipment with a rated current not exceeding 32A for use outdoors.
The maximum disconnection time for a lighting circuit in a commercial premises protected by a TT system is (411.3.2.2 p.58, Table 41.1 p.59)
a) 0.07
b) 0.4s
c) 5.0s
d) 0.2s
d) 0.2s
TABLE 41.1 p.63
Maximum Disconnection Times
411.3.2.2 p.58
The maximum disconnection times stated in Table 41.1 now apply to final circuits rated up to 63 A with one or
more socket-outlets and final circuits rated up to 32 A supplying only fixed connected current-using equipment
411.3.2.3 p.59
In a TN system, a disconnection time not exceeding 5 s is permitted for a distribution circuit and for
a circuit not covered by Regulation 411.3.2.2.
411.3.2.4 p.59
In a TT system, a disconnection time not exceeding 1 s is permitted for a distribution circuit and for
a circuit not covered by Regulation 411.3.2.2.
The maximum Zs for a BS EN 60898 32A B Type circuit breaker protecting a domestic ring circuit is (Table 41.3 p.62)
a) 1.37 Ω
b) 0.68 Ω
c) 0.34 Ω
d) 0.55 Ω
a) 1.37 Ω
TABLE 41.3 p.62
Maximum earth fault loop impedance (Zs) for circuit-breakers with U0 of 230 V, for operation giving compliance with the 0.4 s disconnection time of Regulation 411.3.2.2 and 5 s disconnection time of Regulation 411.3.2.3 (for RCBOs see 411.4.204)
411.3.2.2 p.58
The maximum disconnection times stated in Table 41.1 now apply to final circuits rated up to 63 A with one or
more socket-outlets and final circuits rated up to 32 A supplying only fixed connected current-using equipment
411.3.2.3 p.59
In a TN system, a disconnection time not exceeding 5 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.4.204 p.63
Where an RCD is used to satisfy the requirements of Regulation 411.3.2.2, 411.3.2.3 or 411.3.2.4 the maximum values of earth fault loop impedance in Table 41.5 may be applied for non-delayed RCDs to BS EN 61008-1 and BS EN 61009-1 for a nominal voltage U0 of 230 V.
The maximum measured value for a BS EN 60898 16A B Type circuit breaker is (Table 41.3 p.62)
a) 2.73 Ω
b) 1.37 Ω
c) 0.68 Ω
d) 1.37 Ω
a) 2.73 Ω
TABLE 41.3 p.62
Maximum earth fault loop impedance (Zs) for circuit-breakers with U0 of 230 V, for operation giving compliance with the 0.4 s disconnection time of Regulation 411.3.2.2 and 5 s disconnection time of Regulation 411.3.2.3 (for RCBOs see 411.4.204)
411.3.2.2 p.58
The maximum disconnection times (0.4s) stated in Table 41.1 now apply to final circuits rated up to 63 A with one or more socket-outlets and final circuits rated up to 32 A supplying only fixed connected current-using equipment
411.3.2.3 p.59
In a TN system, a disconnection time not exceeding 5 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.3.2.4 p.59
In a TT system, a disconnection time not exceeding 1 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.4.204 p.63
Where an RCD is used to satisfy the requirements of Regulation 411.3.2.2, 411.3.2.3 or 411.3.2.4 the maximum values of earth fault loop impedance in Table 41.5 may be applied for non-delayed RCDs to BS EN 61008-1 and BS EN 61009-1 for a nominal voltage U0 of 230 V.
The maximum Zs to ensure 30 mA RCD operation is (Table 41.5 p.64)
a) 1667 Ω
b) 500 Ω
c) 167 Ω
d) 100 Ω
a) 1667 Ω
TABLE 41.5 p.64
Maximum earth fault loop impedance (Zs) for non-delayed and time delayed ‘S’ Type RCDs to BS EN 61008-1 and BS EN 61009-1 for U0 of 230 V (411.5.3)
411.3.2.2 p.58
The maximum disconnection times stated in Table 41.1 now apply to final circuits rated up to 63 A with one or
more socket-outlets and final circuits rated up to 32 A supplying only fixed connected current-using equipment
411.3.2.3 p.59
In a TN system, a disconnection time not exceeding 5 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.3.2.4 p.59
In a TT system, a disconnection time not exceeding 1 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.4.204 p.63
Where an RCD is used to satisfy the requirements of Regulation 411.3.2.2, 411.3.2.3 or 411.3.2.4 the maximum values of earth fault loop impedance in Table 41.5 may be applied for non-delayed RCDs to BS EN 61008-1 and BS EN 61009-1 for a nominal voltage U0 of 230 V.
411.5.3 p.64
Where an RCD is used for fault protection, the following conditions shall be fulfilled:
(i) The disconnection time shall be that required by Regulation 411.3.2.2 or 411.3.2.4, and
(ii) RA × IΔn ≤ 50 V
The maximum measured Zs for a BS 3036 30A type fuse supplying a circuit for a cooker, not incorporating a socket outlet, and on a TN system is (Table 41.2 p.61)
a) 1.68 Ω
b) 1.04 Ω
c) 0.91 Ω
d) 0.99 Ω
b) 1.04 Ω
TABLE 41.2 p.61
Maximum earth fault loop impedance (Zs) for fuses, for 0.4 s disconnection time with U0 of 230 V (see Regulation 411.4.201)
411.4.201 p.60
Where a fuse is used to satisfy the requirements of Regulation 411.3.2.2, maximum values of earth fault loop impedance (Zs) corresponding to a disconnection time of 0.4 s are stated in Table 41.2 for a nominal
voltage (U0) of 230 V.
411.3.2.2 p.58
The maximum disconnection times (0.4s) stated in Table 41.1 now apply to final circuits rated up to 63 A with one or more socket-outlets and final circuits rated up to 32 A supplying only fixed connected current-using equipment
411.3.2.3 p.59
In a TN system, a disconnection time not exceeding 5 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
411.3.2.4 p.59
In a TT system, a disconnection time not exceeding 1 s is permitted for a distribution circuit and for a circuit not covered by Regulation 411.3.2.2.
