Lighting fixture take-offs need serious consideration.
The lighting is counted, the branch is wheeled, and you, the estimator, have sent your lighting counts to your vendors. Before you move on to the next system, let’s talk a minute about take-offs in the estimating process for lighting and dimming controls, daylight harvesting, and occupancy sensors.
Occupancy Sensors
Occupancy sensors can be like a simple switch. The light goes on when someone enters the room, and if 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 which work in concert with lighting control and dimming systems. I must say, 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 generally, for each item in the system, you need a stub-up or a box or both. And you must assign a labor factor to each as well as a material quote from your vendor, and carry the labor and material for the wire. That’s it. More daylight harvesting systems are shown lately, as a way to save energy on bright, sunny days. In this case, the sensor detects the presence of daylight, and adjusts the building’s lighting accordingly to save energy.
Branch Devices
Moving on to branch devices, take-offs for these items are pretty straightforward. The things you want to watch out for are notes pertaining to tamper-proof receptacles. They are not as expensive as they once were, but still a good deal more than a standard duplex. Leviton Decora devices and faceplates are certainly more costly than standard 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 would indicate 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 wire. Then you will have to cross-reference this information with the NEMA configuration chart. This can be found either in the NEC code book or in one of the cross reference books, such as Ugly’s. I guess my point is…completing a take-off is more than counting. You have to know what you are looking at and what to look for.
Branch Wiring
Do you wheel off your home runs? What do you carry for each item? You can certainly review the drawings to see what you should carry for an average length for a receptacle, and then take the cable or wire off as you do take-off each device. Always wheel off the branch for specialty outlets to ensure that 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 about this in the specs, then I do my conduit fill to code. Keep in mind that you should run your lighting home runs in separate raceways from your power and certainly from your low-voltage wiring.
Mechanical
Take-offs with 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 from which you could do the same thing. This is handy because you will be able to determine the wiring and voltage requirements of the unit, and whether or not you will have to carry the disconnect. Keep in mind that even if you do not have to carry the material cost for the disconnect, you will still have to carry labor for wiring the disconnect and any control wiring. Pay special attention to whether the equipment is inside or out. Anything outside will need a NEMA 3R disconnect, which is much more pricey than a NEMA 1 disconnect. If the item is in an area designated as “explosion proof,” then you’ll need to use the appropriate wiring method for the Division and Class, and use the appropriate explosion-proof fittings, devices, and disconnects. This can add additional cost to your job. In any event, you want to be sure to cover your costs appropriately.
Installation
The installation of feeders, switchgear and panels is often where most of the money in your job is. It is not just a matter of wheeling off the “from and to” this panel and that. You must ensure that you are using the appropriate method of running the conduit, be it in the slab, on bar joist or on steel beam. Many younger estimators wheel the feeders very tightly, but you want to be sure that you cover your cost and cover extra wire for terminations. Don’t forget to labor your panels and switchgear as well.
Many software programs offer an option to “build” your panel with the appropriate breaker fill. We have found that it is much more cost-effective to come up with labor hours that work for you. For example, we carry 6 hours for 100 amp panels, 8 hours for 200 amp, 10 hours for 400 amp, and this formula works for us. Be sure you know how the panels are going to be mounted. Will they sit on a pad or will they be mounted on the wall? If mounted, will you have to carry Unistrut for mounting? Also, do you have to carry the housekeeping pads? Probably not, but you should always be sure to exclude concrete work if you know you don’t have to carry it. The same would be true of the transformer pad or, if applicable, the generator pad. Speaking of the generator, don’t forget to carry the rigging; and determine whether you need to carry generator fuel, start-up, and testing. If you are not responsible for it, please exclude it from your proposal.
Does your project have emergency feeders? Please read the specifications carefully as emergency feeders may have to be run in MI cable, or they may have to be run in EMT that will be concrete encased. Again, be sure to exclude the concrete work if you know you don’t own it. If you have not bid a job with MI cable lately, call your supply house or check your material pricing service to ensure that you are carrying the right price.
Utilities
Incoming site utilities are generally run in Schedule 40 PVC, but read your specifications and drawing notes to ensure that you can use Schedule 40 PVC, as opposed to Schedule 80 PVC, or PVC coated rigid. In the event that there is a conflict between the drawings, the notes and the specs, submit a Request for Information (RFI). Certainly there is an appreciable labor and material cost difference between these methods, and while you want to cover your costs, you also want to be sure that you do not artificially inflate your labor or material cost. Also, while you will have incoming power requirements, you may also have incoming telephone, CATV or fiber, so be sure to carry what you should. Read the specs to see if you are responsible for manholes or pull boxes, too. Site lighting–are you responsible for site pole bases?
Low-voltage systems may or may not be part of your bid package on any particular job. Be sure you know what to carry: whether it’s simply “rings and strings” and EMT stub-up, or a full-blown system including device installation, pipe, and wire.