learning to do takeoffs

[billdozier]

Hey guys went to look at a job today wiring a barn with a few basic plugs and switches from a subpanel. Simple job work wise. But I struggled trying to figure out exactly how much material and wire will be needed. Is there any tricks you guys use to make sure you cover everything. Or is it just a time thing. Another words the more you do it the easier it gets?

 

[JacksonburgFarmer]

Well.....practice begins to make perfect....


Learning how to estimate accuratley has been one of the hardest things I have ever done.....

My suggestions.....

1. Draw yourself a "print" to take off. Dimensions are nice.
2. Route your runs (conduit/wire)
3. Tally and add em up.
4. Figure your time. (HINT...your not as fast as you think you are.....sometimes you are...somedays....well....not so much....
5. Figure in for contingency....if it is a $500.00 job, not so much....$50, 000.00 and you better pad it some...
6. PROFIT OVERHEAD.

Check your numbers..... several times......nothing is worse than working for nothing.....Been there.....done that......The School of Hard Knocks sucks.....and has a very high tuition rate.....

 

[480sparky]

Get a lap counter at the local sporting goods shop.

Makes counting things like fixtur........sorry, luminaires...... easier and more accurate.

 

[quogueelectric]

It really sucks when you miss something on the takeoff yet sometimes it is the only way you got the job. Sometimes you will see that taking an extra 15 min to doublecheck a takeoff is well worth it when you are finding yourself installing a thousand dollars worth of work for free when you missed it on the takeoff. This learning curve corrects itself fast. Noone to blame but yourself.

 

[e57]

I assume you don't got a super-duper estimating program?

The low-down and dirty method would be to chuck a bunch of material at it, and whatever sticks is what ever goes....

The next ledge from the cliff from that is to make yourself a simple spread-sheet with assemblies and a count of those with a tabulation of each component and costs AND mark-up.... Say a receptacle = Cable connector, box, ring, ground screw, 3 wire-nuts, outlet and a plate. Then create a labor number for it, like whatever it is to complete it. So many minutes for mounting, make-up, etc. Then add PROFIT, AND OVERHEAD!

As for the wire - there are many ways to do this. Some have a sq' ratio to use... But it doesn't always work if you have a bazillion HR's or complicated framing. I have a method that I often safe for when I actually have the job, but sometimes I break it out before... Draw out line diagrams for the circuits, then grab a piece of string. Pull the string in the approximate path, and keep pulling off more string for the next. Then measure the string and scale it.... Then ADD some more ~ 10%. it works pretty good. :grin:

 

[480sparky]

Some figures tend to play off each other, and you can use that to do a spot-check on quantities.

For instance, if you've got 7,000 feet of ?" EMT, does 12,000 feet of 12 THHN sound right?

Will 450 troffers need 600 whips? If they're 3-lamp, will 750 lamps make it?

 

[quogueelectric]

Some figures tend to play off each other, and you can use that to do a spot-check on quantities.

For instance, if you've got 7,000 feet of ?" EMT, does 12,000 feet of 12 THHN sound right?

Will 450 troffers need 600 whips? If they're 3-lamp, will 750 lamps make it?

I just almost got bit by 52 watt HO t5s there are 4 lamps 2-2lamps all dimmable but it is easy to go over on wattage with 4-52 watt lamps 200+ watts per fixture.