RCDs SPDs AFDDs Trip times and circuit protection (use BS7671:2018 Amendment 4:(2026) regs book and OSG)

RCDs should be checked for mechanical operation by pressing the test button on it. How often should this check be performed
1. 6 monthly
2. weekly
3. yearly
4. monthly
State the maximum disconnection time for a general non-time delayed RCBO to BS61008/9
1. 300mS
2. 40mS
3. 500mS
4. 200mS
State the maximum disconnection time for a time delayed RCBO to BS61008/9
1. between 130mS to 500mS
2. between 200mS to 500mS
3. between 100mS to 500mS
4. between 40mS to 500mS
State the letter that denotes a time-delayed RCD
1. type S
2. type M
3. type R
4. type T
State the maximum tabulated earth fault loop impedance value for a BSEN 61008 RCD with a residual operating current of 30mA
1. 1667 ohms
2. 500 ohms
3. 167 ohms
4. 100 ohms
State the maximum tabulated earth fault loop impedance value for a BSEN 61009 time-delayed RCD with a residual operating current of 300mA
1. 167 ohms
2. 500 ohms
3. 1667 ohms
4. 100 ohms
State the maximum recommended earth fault loop impedance value for a BSEN 61009 RCD with a residual operating current of 30mA to ensure stability during a fault
1. 200 ohms
2. 500 ohms
3. 50 ohms
4. 100 ohms
Where a RCD is used for fault protection, identify the formula that should be fulfilled
1. RA x In <= 50v
2. RA x In <= 25v
3. RA x In <= 230v
4. RA x In <= 400v
Identify the type of RCD to be used for fixed equipment where it is known that the load contains no DC components.
1. type AC
2. type A
3. type F
4. type B
Identify the type of RCD to be used on AC current and on residual pulsating DC current loads
1. type A
2. type AC
3. type F
4. type B
Identify the type of RCD to be used for residual pulsating DC currents superimposed on smooth DC current loads
1. type F
2. type AC
3. type A
4. type B
Identify the type of RCD to be used for residual alternating currents superimposed on smooth DC current loads
1. type B
2. type AC
3. type A
4. type F
Identify the type of RCD not to be used for 'general purpose' applications
1. type AC
2. type A
3. type F
4. type B
Identify the maximum disconnection time for a 63A socket circuit on a TN system
1. 0.4 sec
2. 1 sec
3. 5 sec
4. 0.2 sec
Identify the maximum disconnection time for a 40A cooker circuit on a TN system
1. 5 sec
2. 1 sec
3. 0.4 sec
4. 0.2 sec
Identify the maximum disconnection time for a 32A socket circuit on a TT system
1. 0.2 sec
2. 1 sec
3. 5 sec
4. 0.4 sec
Identify the maximum disconnection time for a 40A shower circuit on a TT system
1. 1 sec
2. 5 sec
3. 0.4 sec
4. 0.2 sec
The switching of large Inductive loads can affect the mains electrical supply. This can be protected against by using
1. SPDs
2. AFDDs
3. MCCBs
4. RCCBs
How many types of SPD are there
1. 3
2. 2
3. 4
4. 5
Identify the type of SPD to be installed at the origin of the installation
1. type 1
2. type A
3. type 3
4. type 4
Where would a type 2 SPD be installed
1. at the distribution board
2. at the origin of the installation
3. near the terminal equipment
4. at any convenient position
Where would a type 3 SPD be installed
1. near the terminal equipment
2. at the origin of the installation
3. at the distribution board
4. at any convenient position
Identify the minimum conductor c.s.a for a type 1 SPD
1. 16 mmsq
2. 6 mmsq
3. 10 mmsq
4. 4 mmsq
Identify the maximum length of tails for a type 1 SPD
1. 1 metre
2. 0.5 metres
3. 2 metres
4. less than 0.5 metre
To avoid unwanted tripping, where should type 1 SPDs be installed
1. upstream of any RCD
2. downstream of any RCD
3. near the load
4. between the distribution board and the load
AFDD's are required for the following locations except
1. residential buildings up to 10 metres high (HRRB's)
2. purpose build student accommodation
3. care homes for vulnerable and elderly persons
4. houses in multiple occupation (HMO's)
Where should AFDD's be placed
1. at the origin of the circuit to be protected
2. at the origin of the installation
3. at the main intake position
4. at the mid-point of a circuit
Arc Fault protection Devices are designed to minimise the risk of significant heat cause by arcing for all the following circuit conditions except
1. neutral to earth arcing
2. live to neutral arcing
3. broken live arcing
4. live to earth arcing
AFDDs should be checked for mechanical movement by operating the in-build test button (if fitted). How often should this check be made
1. every 6 months
2. every 3 months
3. every month
4. weekly

RCDs SPDs AFDDs Trip times and circuit protection (use BS7671:2018 Amendment 4:(2026) regs book and OSG)

RCDs Protective Devices, SPDs AFDDs and disconection times. 12 randomised questions from a LARGE question bank.