What is the symbol for 'current carrying capacity' of your selected cable ?
Ib
In
Iz
It
What is the symbol for 'PROTECTIVE DEVICE RATING' in AMPS ?
Ib
In
Iz
It
What is the symbol for current after the application of 'factors' ?
Ib
In
Iz
It
Which one of the following is not a recognised 'factor' used when sizing conductors ?
Ci
Ca
Cg
Cb
What is the correction factor (rating factor) for a semi-enclosed fuse to BS 3036 ?
1.75
0.725
0.5
0.575
When calculating the size of a live conductor, if there are no 'factors' to consider - what minimum current rating MUST the cable be capable of supporting ?
Protective device rating
design current of the equipment being supplied
32 amps
Iz
What is the function of this formula ' ? = mV/A/m ?
volts drop calculation
Total earth loop impedance calculation
(R1+R2) calculation
Ze calculation
What is the maximum disconnection time for a 230v AC circuit supplying fixed equipment not exceeding 32A, on a TT system ?
0.1s
0.2s
0.4s
5s
What is the maximum volts drop on a non-lighting circuit ?
2%
5%
3%
4%
What is the maximum volts drop on a lighting circuit ?
2%
3%
5%
4%
What is the disconnection time for a 230v AC circuit supplying sockets not exceeding 32A, on a TN system ?
5 seconds
0.5 seconds
0.4 seconds
2 seconds
What is the disconnection time for a 230v AC circuit supplying fixed equipment exceeding 32A, on a TN system ?
0.4 seconds
0.5 seconds
5 seconds
2 seconds
If a 'B' type RCBO to BSEN61009-1 - rated at 32A and 30mA, is installed in a TN system to protect a ring circuit in a detached garage, what is the maximum earth loop impedance allowed, to comply with BS7671:2018, with regard to 0.4sec disconnection time ?
1.37 ohms
1.5 ohms
1.09 ohms
1.44 ohms
How is the correct conduit size selected for installing different quantities of cables ?
Minimum 50% space as a general rule
Calculate area of conductors and deduct from conduit size
Select from tables in On-Site Guide by means of cable factors
Use a conduit selection formula
How close should the bonding connection of services pipework be to the corresponding water/gas meter in a domestic dwelling ?
100mm
850mm
600mm
350mm
What is the minimum size to be used for a extraneous bonding conductor (non PME) ?
10.0 sqmm
6.0 sqmm
2.5 sqmm
4 sqmm
What is the minimum size to be used for an exposed and unprotected supplementary bonding conductor connecting two extraneous conductive parts together??
10.0 sqmm
6.0 sqmm
2.5 sqmm
4 sqmm
What is the minimum size to be used for a protected supplementary bonding conductor connecting two extraneous conductive parts together?
10.0 sqmm
6.0 sqmm
2.5 sqmm
4 sqmm
What is the minimum c.s.a of the double-insulated 'tails' from your electricity meter to your consumers unit ?