Re: Estimating BCW
Darrin -- It sounds like you are dealing with plans that only show the locations of the lights, receptacles, switches and other devices. None of this stuff is already circuited out, right?
If that's the case, then the only way I do it is:
1. Count and color (as you count) all of the fixtures and devices.
2. Circuit everything out, drawing in the conduit routing and circuiting as I would do it if I was installing it. You essentially have to design the installation.
3. I still am doing estimates manually (I don't do that many right now, so I can't justify software right now. When I need it, I'll buy it.). So, I use a rotometer of the correct scale (mine are old, look like a pocket watch with a little wheel and a reset button, and you roll them along the conduit route to measure the footage of the conduit.)
4. With a click counter in my left hand and the rotometer in the right, I scale off all of the 1/2" with 2#12. I click the counter once for each run between J-Boxes. That gives me the number of connectors (count X 2), plus 20'/count of conduit + wire if I am looping up and down. I add this to the horizontal length from the rotometer. I color all of this conduit one color so I can see what I took off as 1/2" EMT with 2#12s.
5. Same process for 1/2" with 3#12s, then 4#14s, and all other combinations. I color each combination with a different color.
Boxes, rings, covers, devices, wirenuts, fasteners etc. all derive from the lighting and device counts. Straps, fasteners and couplings and wire come from conduit footages. (sort of a modified assembly take-off method)
I take all of the branch off for the job using something like this method, with variations for different wiring methods.
For feeders, I have feeder take-off sheets that I do by panel by circuit. That way, I don't miss any feeders. It is a "from" "to" system. I start at the transformer and go to the last panel, coloring off stuff as I go.
It's hard to describe, but easy to do with practice. Pretty accurate, but not real fast. Not that slow, though, if you learn good habits and practice.
I haven't taken any estimating classes in a long time, so there are probably better methods and ideas around now.
I'm sure that using estimating software with direct input measuring devices will be much faster. But even when I add this stuff, my general take-off procedure will remain the same until someone shows me a procedure/sequence that works better.
When I completely finished, if I do the project, then I give the color coded drawings and various take-off sheets to my job electrical superintendent.
If he has better ideas, then we change the take-off accordingly. When we agree and everything is double-checked, then the materials are ordered -- they match the drawing layout.
We don't really end up making many field changes after he is on-site, since we are pretty thorough in the planning stage. We look at all of the drawings -- architectural, structural, mechanical, details, etc. I'm big on preplanning -- you catch a lot of mistakes and conflicts before they happen.
He takes this info to the jobsite with him and has it to refer to during construction. He pretty much puts it in according to our plan. That way, all of the materials needed work out, and hardly anything is missing. Everything fits, with very little left over, and very few trips to the supply house.
This probably seems slow and tedious, and it probably is. But I hardly ever run over on materials or labor -- I almost always stay within estimated cost.