Hi James, Would I be correct in saying you would use "Ib" instead of "In" in the case where there was no overload risk to be considered. The use of "In" i have always used in cases where overload would be possible.
Hi Angelo, In most cases it is necessary to use the In in the equation. However if the circuit is supplying a fixed appliance such as a heater that you know the load in watts and it's not possible for the end user to overload it, then it is possible to omit the overload protection, and appendix 4 shows the alternative equation using Ib. However there are some types of installation where it's not permitted. From memory, I think it's not permitted in hazardous areas for example. So it's always worth checking to see if any other regulations apply. Regards James
Scary to think how many DIYers have run cable and not considered correction factors.
Hi James, Would I be correct in saying you would use "Ib" instead of "In" in the case where there was no overload risk to be considered. The use of "In" i have always used in cases where overload would be possible.
Hi Angelo,
In most cases it is necessary to use the In in the equation. However if the circuit is supplying a fixed appliance such as a heater that you know the load in watts and it's not possible for the end user to overload it, then it is possible to omit the overload protection, and appendix 4 shows the alternative equation using Ib. However there are some types of installation where it's not permitted. From memory, I think it's not permitted in hazardous areas for example. So it's always worth checking to see if any other regulations apply.
Regards
James