A wiring material take off that refuses to size a cable category you have not measured.
Electrical and plumbing. 5 questions answered below, each with the arithmetic behind it and the limits of what the tool decides. Open the Electrical Estimator tool.
An electrical estimate is a count and a length. The count is points, the length is the route from the board to each point, and everything else on the page is those two numbers multiplied by the materials a circuit needs. Cable, conduit, boxes, switches and boards all follow from them, which is why the estimate is only as good as the layout it is built from. What the tool will not do is design the installation. Cable size follows current, protection and volt drop, circuits follow the load and the regulations in force where you are building, and both are an electrician's decisions. Once those are made and the points are marked, the material quantity is arithmetic, and that is the part the estimator owns. Where a run has not been measured, it is reported as missing instead of estimated.
A three bedroom house with forty two points, an average run of eleven metres including the drop, gives four hundred and sixty two metres of route. Allow ten percent for dressing and terminations and the cable order is about five hundred and ten metres, split by the sizes you assigned: sockets on two point five square millimetre, lighting on one point five. Add forty two back boxes, the plates for the same count, one distribution board with the ways you specified, and the outlets. The estimate is a count and a length throughout, and the only figure a sparky is likely to change is the route, which is why measurement is the input that matters.
Count the points and measure the routes. The estimate takes your schedule of sockets, switches, light positions and outlets, multiplies each by the run you measured, and returns cable by size, conduit, boxes, plates and the board. Two inputs drive everything: the number of points, which sets the accessories, and the average or measured route, which sets the cable. A layout that is not yet marked up cannot produce a cable figure, and the tool says so.
No, and the page says so. Cable size follows current, protection and volt drop; circuits follow the load and the wiring regulations where you are building; testing and certification follow the installation. The estimate measures materials for a design someone else has made. What it gives you is an order you can price before work starts, which is a different document from a certificate.
Usually because the route differs. An electrician measuring on site follows the actual path through joists, around obstructions and down the wall, and often adds a margin by habit. The estimate uses the length you enter, so if your average run is a straight line between board and point, it will be short. Enter the length you would actually pull, including the drop at each end, and the two numbers converge.
Count what you are installing, not what a schedule of rates assumes for a room. Each socket, switch, light position and fixed outlet is a point with its own run, and the count converts into cable, conduit, boxes and plates. Two rooms with the same floor area can differ by ten points, which is the difference the estimate is built to carry. Counting from the drawing also makes the estimate checkable against the second fix.
Yes, when you enter a measured route. The distance is from the distribution board to the point along the path the cable takes, which includes the climb from the board and the drop from ceiling level to a socket. A route measured along the wall at socket height understates the cable by the drop, which on a two storey building is a meaningful number of metres across the whole job.