After performing a thorough review of the specifications, we learned in last month’s column that there’s much more to the take-off than just counting. Although most estimators often want to get the counts done before they really review the job, it’s important to go over the drawings before you ever uncap your highlighter or open that software program. By taking a proactive approach with this step of the estimating process, you can get a feel for the scope of work and building layout — and, quite possibly, determine anything that seems to be missing from the drawings.
So now that the lighting is counted, the branch is wheeled, and you’ve sent your lighting counts to your vendors, there’s still more to do. Before you move on to the next system, let’s talk for a minute about lighting and dimming controls, daylight harvesting, and occupancy sensors.
Occupancy sensors are like a simple switch. The light goes on when someone enters the room. When the sensor does not “sense” anyone in the room, the light turns off. However, lately we have seen that there are many types of occupancy sensors that work in concert with lighting control, dimming, and building management systems.
I must admit, the first few times I saw a lighting control riser, I thought it was complicated and intimidating. However, when you break down the pieces, you realize that most of the time for each of the items in the system, you need a stub-up, a box, or both — and you must assign a labor factor to each, get a material quote from your vendor, and carry the labor and material for the wire. That’s all there is to it.
Now, let’s move on to branch devices. Taking off these items is pretty straightforward. The things you want to watch out for are notes pertaining to tamper-proof receptacles (not as expensive as they once were, but still a good deal more than a standard duplex), higher end type devices and faceplates (certainly more costly than standard devices), and carrying the proper receptacles for specialty devices. Sometimes, there are keyed notes or a schedule for items requiring something other than a standard duplex, even though the symbol on the drawing indicates a standard duplex. Again, it always pays to read the drawing keyed notes before you start so you can be aware of anything “special” you might have to take-off.
The same is true of kitchen equipment. There is usually a schedule that will either state the proper receptacle, or you will be provided with information regarding voltage, amperage, and the number of conductors. Then you will have to cross-reference this information with the NEMA configuration chart found either in the NEC or one of the cross-reference books, such as Ugly’s. The point is, completing a take-off is more than just counting — you have to know what you’re looking at and what to look for.
It’s time to focus on branch wiring. Do you wheel off your homeruns? What do you carry for each item? You can certainly review the drawings, see what you should carry for an average length for a receptacle, and take the cable or wire off as you take off each device. Always wheel off the branch circuit for specialty outlets to ensure you have enough cable for these items.
I look at the specs and determine how many circuits the specs say to carry in a conduit. If there is no information regarding this in the specs, then I do my conduit fill to Code. Keep in mind that you should run your lighting homeruns in separate raceways from your power — and certainly from your low-voltage wiring.
Taking off mechanical equipment can be made much easier if you print the mechanical schedule and put your lengths next to the schedule, as you find the equipment on the floor plan. Often, however, the electrical drawings will contain a mechanical schedule you could do the same thing from.
This is handy because you will be able to determine the wiring and voltage requirements of the unit and whether you will have to carry the disconnect, starter, and/or VFD. Keep in mind that even if you do not have to carry the material cost for these items, you will still have to carry labor for wiring and possibly the installation plus any control wiring.
Pay special attention to whether the equipment is located indoors or outdoors, because anything placed outside will need a NEMA 3R disconnect or possibly stainless steel, which are both pricier than a NEMA 1 disconnect. If the item is in an area designated as “explosionproof,” then you will have to use the appropriate wiring method for the specified Division and Class as well as the appropriate explosionproof fittings, devices, and disconnects, which can add additional cost to your job. In any event, make sure you cover your costs appropriately.
Next time, we will discuss site utilities, including site lighting, feeders, and low-voltage systems. As you can see, completing a take-off takes time, as does writing about it!
Candels is president of Candels Consulting, an electrical estimating consulting firm in Niantic, Conn. She can be reached at firstname.lastname@example.org.