The box fill calculator works out ↳ device or equipment fill volume allowance, ↳ equipment grounding fill volume allowance and ↳ support fittings fill volume allowance from are you using a box with internal clamps?, number of devices, number of grounding conductors, number of conducting wires, will you need some support fittings?, one way, grounding wire volume, largest conducting wire size and largest grounding wire size. Enter what you have and the relationship is applied straight away, so you get the answer without working through the algebra yourself.
What Is the Box Fill Calculator?
The box fill calculator turns are you using a box with internal clamps?, number of devices, number of grounding conductors, number of conducting wires, will you need some support fittings?, one way, grounding wire volume, largest conducting wire size and largest grounding wire size into ↳ device or equipment fill volume allowance, ↳ equipment grounding fill volume allowance and ↳ support fittings fill volume allowance, so you can order the right amount of material the first time.
Material estimates are where projects go over budget. Getting the quantities right before the delivery arrives is worth more than any discount on the order.
How to Measure for the Box Fill
Measure everything in the same unit and take the largest dimension you can reasonably use rather than the average. Formwork, ground conditions and cutting waste all push the real figure above the theoretical one.
Where a plan calls for a specific thickness, check it against local building regulations before you order. The calculator reflects the relationship, not the code.
Allowing for Waste and Errors
Order a little more than the calculation suggests. The gap between the theoretical quantity and what actually arrives on site is normally waste, spillage, over-excavation and uneven grading, and all of it comes out of the same budget.
Write the figures down and compare them with what you actually used on site. That is how you build an estimate you can trust for the next job.
A Worked Example
Working through an example, with are you using a box with internal clamps? set to 0, number of devices set to 10, number of grounding conductors set to 5, the calculator returns ↳ conductor fill volume allowance of 2, and ↳ clamp fill volume allowance of 0, and ↳ support fittings fill volume allowance of 0. Substitute your own figures and the same steps produce the same kind of answer.
Frequently Asked Questions
What do I need to work out ↳ device or equipment fill volume allowance?
Enter are you using a box with internal clamps?, number of devices, number of grounding conductors, number of conducting wires, will you need some support fittings?, one way, grounding wire volume, largest conducting wire size and largest grounding wire size. The calculator then works through the relationship and reports ↳ device or equipment fill volume allowance, ↳ equipment grounding fill volume allowance and ↳ support fittings fill volume allowance.
What does the box fill actually calculate?
It takes are you using a box with internal clamps?, number of devices, number of grounding conductors, number of conducting wires, will you need some support fittings?, one way, grounding wire volume, largest conducting wire size and largest grounding wire size and converts them into ↳ device or equipment fill volume allowance, ↳ equipment grounding fill volume allowance and ↳ support fittings fill volume allowance using the standard relationship for this problem. Each step is applied in turn, so every output is traceable back to the numbers you typed in.
How should I enter are you using a box with internal clamps??
Use the value you actually have, in the unit shown next to the field. Enter every value in the same unit system. The calculator assumes the figures you supply are consistent, so it cannot correct a mistake that happens before the calculation starts.
Is the answer exact?
It is as exact as the formula and the inputs allow. The method itself is the standard one for this problem, so the only sources of error are the figures you enter and the precision you ask for.
Do I have to fill in every field?
Only the fields a particular result depends on. If you leave one blank, the results that need it simply show a note instead of a number, and everything else still works.