This applies to vehicles parked on a restricted road.
It covers all day Saturday and Sunday and 6pm to 7am Monday to Friday.
It doesn't cover general motorcars, small vans or motorcyles.
It does cover HGV's, trailers and small goods vehicles. In relation to goods vehicles they cannot be over 6m in length or 2m in height.
The important factor is the unladen weight of the vehicle. If it is under 3050kgs then it is classified as a motorcar, irrespective of size.
A motorhome is classified as a motorcar if the unladen weight is under 3050kgs and therefore the length and height restrictions do not apply to them. They can legally park anywhere a car can.
It makes no difference whether the vehicles are used privately or commercially, the Act makes not such distinction.