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ElEctrical FEEdEr installation

Technical Paper

HowToEstimate the Cost of

submitted by Richard Lohnes, CPEmember of Boston Ch. 25

What successful Cost Estimators know. . . . and you should, too.

AN ESTIMATOR’S GUIDE TO POLICIES, PROCEDURES, AND STRATEGIES>>>>>>>

>>>>>>>>>>>

Richard Lohnes, CPE is an Electrical Estimator in Boston, Massachusetts. He has a Bachelors Degree in Electrical Engineering from Northeastern University. His career as an estimator includes bidding State and Federal Projects for various types of electrical construction including commercial, institutional, exterior electrical distribution, wind power, substation and switching stations up to 500kV. He has been an estimator for 30 years and is currently employed as an estimator in the Transmission Line Engineering department for a major utility company.

1) Introduction 2) Types and Methods of Measurements 3) Feeder Takeoff (Quantity Survey) 4) Special Factors 5) Overview of Labor, Materials, Equipment, Indirect Costs, & Approach to Markup 6) Special Risk Considerations 7) Ratios and Analysis 8) Misc. Pertinent Information 9) Sample Sketches10) Sample Takeoff & Pricing Sheets11) Glossary12) References

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ELECTRICAL FEEDER INSTALLATION

1. introductionEstimators have a lot of responsibility

in preparing estimates, usually with little time and resources. A disciplined approach to each project estimate will increase the likelihood of positive results. Electrical feeders represent one of the major costs in the electrical contractors bid, especially in larger projects such as hospitals, schools, treatment plants, or multi story buildings.

This paper will provide an overview of how to estimate the installation of electrical feeders for a fixed price project. It will provide the fundamentals for generating an accurate takeoff of electrical feeders that can be applied to any size project.

Main csi division: 26 00 00 – Electrical

Main csi sub-divisions: 26 05 19 – Low-Voltage Electrical Power Conductors and Cables

26 05 33 – Raceway and Boxes for Electrical Systems

26 05 33.13 – Conduit for Electrical Systems

26 05 33.16 – Boxes for Electrical Systems

26 05 36 – Cable Trays for Electrical Systems

26 05 39 – Underfloor Raceways for Electrical Systems

26 05 43 – Underground Ducts and Raceways for Electrical Systems

26 05 48 – Vibration and Seismic Controls for Electrical Systems

Brief descriptionThis paper will outline a method for

performing quantity takeoff, application of material prices and labor hours for the electrical feeder installation portion of an electrical subcontractors bid. The resulting material costs and labor hours are added to the costs of the other electrical systems, indirect costs and markups to form a total lump sum electrical bid; however this paper will address only the feeders. It will illustrate ways to analyze the results in order to perform a self-check.

An electrical feeder is a circuit consisting of conductors in conduit or a busway run which carries power from the service equipment to a sub-feeder panel or a branch circuit panel or to some point at which the power is broken into smaller circuits. In general, the more power a feeder transfers, the larger the conduit

and wire required, the higher the cost. The sample estimate in this paper

will include electrical feeders for new construction, two story, core and shell, 20,000 square foot office building, 100% design.

The electric service to the building is 1600 Amp, 120/208 Volts. The power company will provide the pad mount transformer and terminate the secondary conductors. Refer to figures 1, 2, 3 & 4 for floor plans and the single line diagram.

This example will include secondary service feeders from the power company transformer to the main switchboard and feeders from the main switchboard to a panelboard in an electric closet on each floor.

2. typEs and MEthods oF MEasurEMEnts

Common measurements used will include each (EA), linear foot (LF), vertical linear foot (VLF) square foot (SF), per thousand (M), per hundred (C), and Lump Sum (LS).

Electrical feeders are measured by linear foot and typically consist of some type of conduit that contains multiple wires or conductors.

Electrical conduit is priced in dollars per hundred linear feet and comes in ten foot lengths. The measured length should be rounded to the nearest factor of ten.

Please note that some types of PVC and HDPE electrical conduit come in other than ten foot lengths so it is important to understand the products specified.

For horizontal distances, conduit should always be measured at right angles (90 degrees). Risers or vertical distances should also be added to the length of the feeder. This includes the vertical distance for conduit run out of the top of the electrical equipment, conduit run into the bottom of the electrical equipment from below and/or conduit run between floors. It is important to review the elevations on the architectural drawings in order to obtain the distance between floors.

The architectural drawings may also show details or information that may prevent installation of the feeders along the shortest route (such as atriums or elevator banks).

In addition to the conduit, hangars and

various types of fittings such as couplings, connectors, condulets, factory elbows or 90’s, and pull boxes should also be included in the takeoff.

Wire is priced in dollars per thousand feet. The quantity of wire depends on the length of conduit measured for the feeder. Each feeder consists of 3 to 5 conductors. In addition to the wire length, the wire make-up length should be added. The wire make-up length is the distance that the wire extends out of the conduit to the point of termination.

Wire terminations are not included in the feeder costs. The labor for wire terminations is included as part of the equipment installation.

3. FEEdEr takEoFF (Quantity survEy)

The estimator should take the following steps prior to starting the takeoff:

• Confirm receipt of a complete set of plans.

• Perform a thorough review of plans and specifications

It is better to take off the switchgear and panels before performing the electrical feeder takeoff so there will be a better understanding of where the electric rooms and panels are located.

The plans typically include a single line diagram (See Figure 4) and/or a feeder schedule (See Figure 5) to identify the feeders. A feeder single line diagram is a schematic that maps the feeders between the electrical equipment. Each line represents a feeder and either calls out the required conduit and wire or references a feeder schedule. A feeder schedule identifies the various feeders and specifies the size and number of conductors and conduits for each referenced feeder.

There are several ways to compile the feeder quantities for pricing. The preferred method is to list each feeder individually. Feeders that are listed individually should be clearly identified (for example: From MSB to HP1). It will be easer to find if there are any changes.

It is more efficient to use a feeder takeoff sheet (See Figure 6) for larger projects that have a lot of feeders. The feeder takeoff sheet is used to summarize a total quantity for the common size feeders. The estimator will be able to price or input each feeder size one time.

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The feeder takeoff sheet should include the drawing number, from, to, length, conduit size, quantity of fittings and pull boxes, wire size, number of wires, and wire makeup length. Start the feeder takeoff at the source (in this example the power company transformer) and then each subsequent feeder indicated on the single line diagram. Highlight each feeder as they are measured and listed on the takeoff sheet, the pricing sheet or directly entered into the estimating software. The following is a summary of the steps necessary for each feeder:

• Identify the feeder on the single line diagram.

• List on the pricing sheet, takeoff sheet or estimating software (From MSB to HP1 for example).

• Measure the horizontal distance using a ruler, scale or on screen takeoff.

• Add the vertical distance.• Enter the total conduit length• Add conduit fittings• Add the wire length ( = (total conduit

length + wire make-up length) x the number of conductors)

• Highlight the completed feeder

List the following for each feeder:• Conduit size and type (EMT, GRC,

PVC, etc)• 90’s, couplings, connectors or

conduit terminations.• Special fittings (condulets, cable

supports, Sealing fittings)• Hangars • Number of wires, size and type• Pull boxes• Coring, Cutting and Patching• Fire seals and Water seals

From transformer to MsBThis feeder is sometimes called the

secondary service. It is the feeder that brings power from the utility point of connection to the service equipment. The utility company should be consulted in order to confirm their requirements and whether there will be any charges for their work.

According to the single line diagram, this feeder consists of 4-4” conduits with 4#600 in each. The specifications require galvanized rigid steel conduit (GRC) within ten feet of the building and 36

inch radius 90-degree elbows. The conduit will be concrete encased (concrete furnished and installed by others). WSK sealing fittings are required for each conduit penetration through the foundation wall. Excavation, backfill, compaction, and concrete is by others. Coring through the foundation should also be included with this feeder.

The horizontal distance from the center of the transformer to MSB is 10LF. The Main Switchboard (MSB) is approximately 7’ 6” H and is located in the basement which is 15FT floor to ceiling. The conduit will enter the top of MSB. In this case the height of the 36 inch radius 90-Degree elbows will cover the vertical distance.

The total amount of GRC required is 40LF (4 conduits x 10LF).

Allow 10FT of wire makeup length per conductor at the switchboard and 5FT at the transformer for a total of 15FT. The calculation for the wire quantity is:

10’ + 15’ = 25’ x 4 conductors = 100LF per conduit x 4 conduits = 400LF of #600 THHN/THWN.

interior FeedersThe riser diagram shows that the feeders

for each panel originate at the Main Switchboard MSB. The electrical drawings indicate that the panels are located in electrical closets directly above each other (stacked electric closets). The feeders can be run along the same route in the basement and run up to the panels in a common location. This is the more cost effective way to install the feeders because they are run together. The conduit will be installed on trapeze hangars, a system of threaded rod and unistrut. The trapeze hangars will be installed approximately every 8 feet. These can be included with the first conduit run of the takeoff.

Sheet E1 shows the proposed routing for the feeders in the basement. Most projects do not show the proposed routing. It is usually determined by the estimator based on experience, a thorough review of the plans and/or existing field conditions (for remodel work).

From MsB to panel hp1 (4#500 & 1#3 4” EMt)

The measurement of the horizontal run from MSB to Panel HP1 and the vertical distance out of MSB can be used for all three feeders. The difference will be the vertical runs through the electric closets.

The measured distance is 110LF plus 5 vertical linear feet (VLF) from MSB and

5 VLF to HP1 for a total of 120LF of 4” EMT conduit. A pull box is required by code because there are more than three 90 degree bends in the run. Separate pull boxes can be included for each run or one larger pull box for all of the feeders. The wire quantity will be 120LF + 10FT makeup length at MSB and 5FT makeup length at HP1. A total of 540LF of #500 and 135LF of #3 will be required for this run.

From MsB to panel pp1 (4#4/0 & 1#4 3” EMt)


5 VLF up to PP1 for a total of 120LF of 3” EMT conduit. A cored hole through the floor and fireproofing should also be included. The wire quantity will be 120LF + 10FT makeup length at MSB and 5FT makeup length at PP1. A total of 540LF of #4/0 and 135LF of #4 will be required for this run.

From MsB to panel pp2 (4#4/0 & 1#4 3” EMt)


20 VLF up to PP1 for a total of 135LF of 3” EMT conduit (include 140LF of 3” EMT). A cored hole through the floor and fireproofing should also be included. The wire quantity will be 140LF + 10FT makeup length at MSB and 5FT makeup length at PP1. A total of 600LF of #4/0 and 150LF of #4 will be required for this run.

Refer to figure 7 for the computer generated takeoff of material for each feeder.

The costs for each of these feeder “assemblies” can be recorded and used for conceptual estimates or budgets. For example: 200A Feeder (4#4/0 & 1#4 3” EMT). The average LF for the type building can be used for budgeting purposes. Storing the assemblies in the estimating software database makes it easier to keep material prices up to date through the use of a pricing update services.

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4. spEciFic Factorschoice of Materials

There is a lot to consider when estimating the cost of electrical feeders.

The estimator must take the time to perform a thorough review of the plans and specifications. Specification requirements for materials such as conduit, conduit fittings, conductor insulation, conductor material (copper vs. aluminum), and pull boxes will impact the price. Specifications for treatment plants may require a more expensive tinned copper conductor and/or more expensive conductor insulation.

If a special or non-stock wire is specified, a minimum order might be required. Non-stock wire could require a minimum order of 25,000 feet even though only 5,000 feet is needed for example.

In a typical commercial building, the specifications may require the feeders to be installed in EMT conduit. If EMT is specified then further review is necessary to determine what type fittings are allowed. EMT fittings are available in die cast set screw, steel set screw, die cast compression and steel compression.

Heavy industrial facilities may require more expensive conduit. For example, PVC coated Rigid Steel Conduit is usually specified in hazardous or corrosive locations and is about three times the cost of Rigid Steel Conduit. Aluminum conduit is typically specified in MRI installations in hospitals.

Architectural and elevation drawings may require a specific routing of the feeders that could increase the length and cost.

small Quantities vs. large Quantities

The estimator must exercise caution when applying price and labor to the estimate. If there are small quantities of conduit and / or wire, the cost of the materials might result in a higher per unit cost. Minimum quantity purchases, availability and freight could also impact the cost. Larger quantities typically result in lower cost per foot. It is the equivalent to buying in bulk. Labor hours are also impacted by smaller quantities. Labor units are based on averages and include setup time. A twenty foot run may require the same set up time as a two hundred foot run resulting in a higher labor per foot for the shorter run.

Geographic location The geographic location will impact

labor costs as hourly rates vary between states and counties, especially union projects and those that require prevailing wage rates.

A tight labor market or lack of qualified workers could impact a projects cost due to the additional travel, lodging and per diem costs necessary to hire from outside the area.

Sales tax, gross receipts tax, municipal and county tax rates vary and the estimator must be creative in finding ways to find the correct information especially if it is the first time working in that state. Specifications for Federal projects typically make the contractor responsible for applicable state, local and federal taxes. If someone at the state department of revenue incorrectly states that you do not have to pay sales tax because it is a Federal Project, it does not relieve the bidder of the responsibility of paying sales tax. So it would be a good idea to ask several local suppliers or subcontractors who have worked on similar projects.

Existing BuildingsWork in an existing building may require

coring, cutting, patching and painting. The specifications should define who is responsible. The estimator should also visit the site when the work is in an existing building in order to verify existing conditions.

If the existing building is going to be occupied during construction then the estimator needs to consider maintaining power and scheduling outages when providing final connection of the new feeders. The owner may require all outages to be taken after hours or on weekends, so overtime costs may need to be included.

seasonal effect on workExtreme hot and/or cold will impact

labor productivity and the estimator must take into consideration the schedule and determine if all or a portion of the labor should be factored.

adder for conduit & Wire wasteSome companies add a percentage to

the material quantities or cost in order to account for waste. Tracking the material costs on projects will allow the estimator to gauge how much waste to add.

5. ovErviEW oF laBor, MatErial, EQuipMEnt, indirEct costs, and approach to Markups.

The estimate provided for the sample project includes estimated material costs and estimated labor hours. The material costs and/or quantities should be reviewed and adjusted for current pricing, minimum quantities, waste and escalation. Applicable sales tax should be included.

The labor units should be reviewed and factored based on quantities and/or site conditions. Figure 8 shows the make up of a typical labor unit and includes suggested labor factors for conduit and wire. The total labor hours are multiplied by the average fully burdened hourly rate in order to determine the labor cost.

The labor and material were summed up as a stand alone estimate for analysis.

Figure 9 is a bid summary report of the total costs for the feeder portion of the project.

6. spEcial risk considErations

There are many risks related to estimating the cost of electrical feeders. Unoccupied buildings should be fairly straight forward to estimate.

Estimating feeders in an occupied facility such as a hospital or a data center requires a good understanding of the restrictions that may be imposed on the project. The specifications may require that all work be performed after hours or outages might only be allowed on weekends and require overtime. Some facilities might limit outages for several hours at a time and require a standby generator which could significantly impact the cost.

The estimator should also be aware of the completion date for a project. Some projects might be fast track and require three shifts in order to finish on time. Overtime can impact productivity, so labor should be factored to reflect the increased cost.


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Labor should also be factored for high rise buildings (approximately 1 to 2% per floor over 4 floors).

Escalation for material and/or labor has to be considered for projects that will take a year or more to complete. The metals market has been volatile and the cost of copper can skyrocket impacting wire prices. Companies sometimes include current prices and ride the market if they are awarded the project. Some companies lock in the wire prices for 6 months or more. Although it prevents a loss from a spike in the wire prices, the company could also end up paying a lot more than the wire is worth if the cost of wire goes down.

7. ratios and analysisThere are several quick checks that

estimators can use to ensure that the estimate of the feeders for a project is “in the ball park”. If these checks both fall within the range for similar (preferably completed) projects, then there is a good chance that nothing major was missed. The secondary service feeder should not be included in this analysis because the distance to the point of connection to the utility can vary significantly between projects.

First, calculate the Material / Labor Ratio by dividing the material cost (including tax) by the total cost and the labor cost by the total cost.

Material - $11,110 / $22,353 ~ 50%Labor - $11,243 / $22,353 ~ 50%

If the material / labor ratio for similar projects are 50:50 then the estimate is most likely on track. If the material / labor ratio turned out to be different, then the estimator should take a second look and figure out why there is a difference.

Unit ratio calculations provide another way to check an estimate. Unit ratios can be calculated using a standard excel spreadsheet. One can be setup and used for every project (Figure 10). There are many ways to look at the feeder costs with the unit ratio sheet. For example, the estimator might first look at the average material cost per feeder (total feeder $ divided by the quantity of feeders) and the average labor hours per feeder (total hours divided by the quantity of feeders). If the cost falls within the range for similar projects, there is a good chance the estimate is accurate. If the averages don’t fall within the range for similar projects, then the estimator should try and validate the data.

The estimator might look at the LF per feeder or the average number of conductors.

If similar projects have an average of 120 LF per feeder and the average for this project works out to be 20 LF, then the feeder lengths might be an area to

check. Or, if the average number of conductors works out to be 2 on the unit ratio sheet (wire quantity / total conduit length), then the wire quantities might be worth checking. The electrical service for this project is 3 phase 4 wire which means

the average number of conductors should be about 5.5. ( 4 wires, plus a ground, plus the make up length).

The above checks work well if they are done for every project. The estimator will develop a level of confidence in that there is a mechanism in place to confirm the accuracy of the estimate. The key is in understanding the differences between projects and comparing apples to apples.

8. MiscEllanEous pErtinEnt inForMation

The estimating technique outlined above is one of many methods to estimate the cost of electrical feeders. These steps provide the estimator the basics to produce an accurate list of materials necessary for the work. The challenge is in developing the skills to estimate how much labor it will take to install those materials. Ask twenty estimators how much it will cost to install a 200A feeder and more than likely you will get twenty different answers. Monitoring and control is important to the success of a company’s estimating department. This requires the proper training of field personnel about reporting and tracking costs. The estimating department needs to get feedback and see reports that show actual costs versus estimated costs. Estimating is not an exact science. One size labor unit does not fit all and the estimator has to understand how to factor labor units based on the overall scope of work. This takes time and experience.

9. saMplE skEtchEs ALL SAMPLE SKETCHES ARE AVAILABLE ONLINE - www.aspenational.org


Basement Floor plan First Floor plan second Floor plan

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9. saMplE skEtchEs


First Floor & Second Floor Plans are available online: www.aspenational.org

Digital Versions: Click on the pictures/graphics to view the PDF.

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All Sample Sketches & Estimates are available online: www.aspenational.org

Digital Versions: Click on the pictures/graphics to view the PDF.

9. saMplE skEtchEs continued


10. saMplE EstiMatE

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Quote from the author:

“Achieving status as a CPE through ASPE certifies that I have the training, skills, and discipline required of a professional estimator. With a degree in engineering and 30 years experience, the CPE rounds out my credentials. Joining ASPE has also opened the door for networking with other professional estimators throughout the country.”

Richard Lohnes, CPE | Analyst / EstimatorNational GridWaltham, MA


11. GlossaryConductor: A conductor is a material which permits a flow of electricity, typically copper or aluminum.Secondary Service: Wires run from the utility company transformer to the buildings main service equipment.Feeders: Conductors which carry electric power from the service equipment (or generator switchboard) to the overcurrent devices for groups of branch circuits or load centers supplying various loads.Panelboard: A single panel or group of panel units designed for assembly in the form of a single panel: includes buses and may come with or without switches and/or automatic overcurrent protective devices for the control of light, heat, or power circuits. Service Conductors: The supply conductors that extend from the street main or transformers to the service equipment of the premises being suppliedService Equipment: The necessary equipment, usually consisting of a circuit breaker or switch and fuses and their accessories, located near the point entrance of supply conductors to a building and intended to constitute the main control and cutoff means for the supply to the building.Switchboard: A large single panel, frame, or assembly of panels having switches, overcurrent, and other protective devices, buses, and usually instruments mounted on the face or back or both. Switchboards are generally accessible from the rear and from the front and are not intended to be installed in cabinets

12. rEFErEncEsConest Software Systems Manchester, NHNECA Manual of Labor Units 2009 – 2010

RS Means Electrical Cost Data

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All Sample Estimates are available online: www.aspenational.org

Digital Versions: Click on the graphics to view the PDF.

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