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Evaluation of Electrical Feeder and Branch Circuit Loading: Phase 1

MEETING MINUTES PROJECT TECHNICAL PANEL MEETING

CONFERENCE CALL TUESDAY, 15 NOVEMBER 2016; 10:30 AM

1) Call to Order and Attendees. The meeting was called to order at 10:30 am by Casey Grant of the Fire Protection Research Foundation. The purpose of the meeting was to clarify and discuss the anticipated project deliverables, and provide guidance toward the final wrap-up of this phase 1 effort. The following were in attendance:

Mike Anthony, University of Michigan (MI)

Mark Early, NFPA (MA)

Lou Galante, University of Iowa (IA)

Jeff Gambrall, University of Iowa (IA)

Tammy Gammon, Jasper Georgia (GA)

Bob Goodwin, University of Iowa (IA)

Casey Grant, Fire Protection Research Foundation (MA)

Brian Meyers, University of Nebraska (NE)

Bob Wajnryb, The Ohio State University (OH)

Bob Yanniello, Eaton Corporation (OH) 2) Review of Project Deliverables. Tammy Gammon provided a review of the project deliverables using the slides included in Attachment A. This resulted in the following observations, questions and comments:

Literature Review

Observation: The initial discussion addressed various details that have been revealed during the project’s literature review (see slides 3 through 6 of Attachment A).

Observation: Focus has been on commercial building loading, and the reduction on power loads due to energy codes, etc. (see slides 3 and 4 of Attachment A). This project is ultimately seeking data to support clarifying levels that are conservatively safe, but realistically efficient and effective.

Observation: Discussion of typical transformer losses (see slides 5 and 6 of Attachment A).

From Slide 5: o DOE established new efficiency requirements in 2016. Newer transformers are more

efficient.

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o Transformer losses can be reduced by selecting more efficient core types, lower rise temperature, and appropriate k‐factor rating.

o Increasing transformer loading does not necessarily reduce power losses.

Comment: There have been miss-perceptions on overloading transformers and their efficiency. We need to not propagate miss-information.

Question: Clarify the over-sizing of transformers. Answer: The best way to decrease power losses of transformers is to carefully select the core types, etc. Newer models are typically more efficient.

Comment: Arc-flash is an important issue. Don’t believe that oversized transformers are an increased risk for arc-flash.

From slide 6: o Difficult to sustain arc at transformer secondary (208Y/120). Few known incidents. o 1584‐2002 arc current equation does not accurately predict low‐voltage, low magnitude

arcing faults currents (too high and assumes self‐sustaining). o Transformer sizing “one size up” does not necessarily create greater risk.

Comment: Risk seems to go up, but it’s arguably not proportional.

Observation: The literature review is still under development, and further work on this is forthcoming.

Data Collection Plan

Observation: The data collection plan is the primary focus of this project (see slides 7 through 15 of Attachment A). The details of the data collection plan were reviewed.

Observation: If necessary, we could streamline the approach to only a lighting study or something similar, based on limited resources for phase 2. Results arguably would be of interest to multiple groups.

Observation: Commercial building study options were reviewed (see slide 8 of Attachment A).

Observation: Need to select buildings that provide regional diversity (see slide 9 and 11 of Attachment A).

Observation: Suitability of prospective sites was reviewed and discussed, including what is acceptable and preferable. The various factors for suitability were clarified.

Observation: Four basic options for site monitoring were discussed (see slides 12 through 15 of Attachment A).

Question: Clarify spot measurements, are they instantaneous? Answer: Some type of temporary measurement for a defined time interval is needed. The resources of the phase 2 project will define the time frames. The measurement would focus on current based on reasonably available monitoring equipment, including how it logs its data and communicates the information.

Observation: Cost of monitoring equipment and installation costs will be the significant resource issue for phase 2.

Question: Clarify our role in proceeding with recommending certain specific options? Answer: This is arguably determined by what the applicable CMP will accept for relevant code changes. A task group with CMP-2 would be useful.

Comment: We do expect phase 2 to be expensive, but the potential cost-savings would justify this.

Comment: While lighting is important, the sizing of branch circuits is viewed as the low-hanging fruit. Branch circuit wiring has the most potential for improving efficiency. However, this will increase the resources needed to collect the appropriate data. For example, it may need to be a $2M project rather than $0.5M project.

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Comment: A particular utility group is approaching the sizing based on a deductive approach.

Comment: We need to clarify what scenarios appeal to the applicable NEC code making panels.

Observation: The various choices discussed are helpful, and ideally we need to summarize and package these in a table or similar, to facilitate additional consideration for the phase 2 effort.

Question: Final report is due on 9/Dec, though contractor would like at least an additional 10 days. Answer: Yes, this is not a problem, and it is more important to have a good work deliverable than to be rigid on this time frame.

Comment: Push to continue with a task group on CMP-2 to expand and further address this, to clarify the value-added of each option and what should be pursued for a phase 2 effort.

Comment: For a phase 2, consider including utilities among the interested end user’s. 3) Next Steps. Tammy Gammon will work to finalize the project deliverables based on this feedback and guidance. Once available, Casey Grant will circulate the final draft of the project deliverables for Phase 1 to the Panel and Sponsors (in December 2016). Comments will be solicited on the final report from the Panel and Sponsors to finalize and close-out the phase 1 effort. Casey Grant will work with NFPA staff (Mark Early) and CMP-2 Chair (Mark Hilbert) to consider a Task Group that can further clarify the specific options for a data collection plan that is considered optimum for possible code revisions. Once the details of a phase 2 effort are clarified, moving forward with obtaining funding can commence with renewed focus. 4) Adjournment. Panel members were thanked for their participation, and the meeting adjourned at 11:40 am.

(Meeting Summary by C. Grant, 21/November/2016)

Attachments Attachment Description No. of Pages

A PowerPoint Slides of Project Status Review 3

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Evaluation of Electrical Feeder & Branch Circuit

Loading: Phase 1Thursday November 15, 2016, 10:30 am EST

Selected Contractor: Tammy Gammon, PhD, PE

Technical Panel: Mark Hilbert, Robert Arno, Mark Early, & Brian Liebel

Sponsors: University of Minnesota, Ohio State, University of Iowa, UT-Austin, Michigan State, Michigan Assoc. of Physical Plant Administrators,

Notre Dame, University of Nebraska, Ohio State, Eaton

Fire Protection Research Foundation

Evaluation of Electrical Feeder & Branch Circuit

Loading: Phase 1Today’s Agenda

Literature Review: Overview & Transformer Issues

Discussion of Data Collection Plan

Fire Protection Research Foundation

Commercial Building Loading

• Electrical feeders and branch circuits provide electricity to major and minor end use loads. Loading depends on building type, geographic location, year of construction and building ownership.

• Buildings are designed to comply with NEC. NEC 220 has changed little over the years (of special interest here – lighting and receptacle loads).

• The DOE supports energy conservation code (ASHRAE 90.1, IECC, federal and state [CA]) development and adoption.

• The DOE also sets minimum energy performance standards for commercial appliances, lighting, motors, transformers, etc.

3

Commercial Building Loading

• As equipment like lighting, computers, and office equipment have become more energy efficient, their power requirements have reduced. Increased efficiencies and energy conservation practices result in reduced lighting and receptacle power requirements.

• Project Focus: Establishing appropriate load demand requirements that are conservatively safe (system safety and reliability) but are also responsive to energy conservation and sustainability issues.

• Relevant research suggested oversizing transformers creates significant power loss. RFP stated: “In addition, larger than necessary transformers that supply power to feeder and branch circuits expose unnecessary flash hazard to electricians working on live equipment.”

4

Transformer Losses

• DOE established new efficiency requirements in 2016. Newer transformers are more efficient.

• Losses can be reduced by selecting more efficient core types, lower rise temperature, and appropriate k-factor rating.

• Increasing transformer loading does not necessarily reduce power losses.

480-208Y Transformers & Arc Flash Hazards

• Difficult to sustain arc at transformer secondary (208Y/120). Few known incidents.

• 1584-2002 arc current equation does not accurately predict low-voltage, low-magnitude arcing faults currents (too high and assumes self-sustaining).

• Transformer sizing “one size up” does not necessarily create greater risk.

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Data Collection Plan

• Determine type of commercial building study (three options)

• Identify prospective buildings and select best study candidates

• Select metering equipment (if not self-funded and within budget)

• Monitor sites and collect data (four options)

• Analyze data and assess regarding NEC 210-230

• Depending on scope of data collection and sponsorship interests, results may be valuable to various government entities, standards organizations, manufacturers, electric utilities, and consultants

7

Commercial Building Study Options• The Sixteen Commercial Building Types as identified in the 2012 CBECS

• 204 commercial buildings total -- 12 for each of 15 types (excluding offices)

• 12 for office buildings up to 50,000 sq. ft. and 12 for those over 50,000 sq. ft.

• Large University Campuses• 137 commercial buildings, with a focus on 50 office buildings as follows:

• 25 offices up to 50,000 sq. ft. and 25 offices over 50,000 sq. ft.

• 25 residence halls, 25 education buildings, 25 laboratories, 12 hospitals

• Fifty Commercial Office Buildings• 25 offices up to 50,000 sq. ft. and 25 offices over 50,000 sq. ft.

• 25 offices under 25,000 sq. ft. ideally equally divided as three groups: 1,000-10,000 sq. ft., 10,000-25,000 sq. ft., and 25,000-50,000 sq. ft.

• For 25 offices over 50,000 sq. ft., ideally including 10 offices over 100,000 sq. ft. and 5 over 200,000 sq. ft. 8

BUILDING SELECTION GEOGRAPHICALLY Geographic Selection and Monitoring Sites

10

13

IECC

Zones

3 DOE

Added

Most

Populated

City

Office Resi-

dence

Halls

Edu-

cation

Labs Hos-

pitals

1 1 Miami 12 2A Houston 5 4 4 4 23 2B Phoenix 24 3A Atlanta 5 3 3 3 15 3B Other Las Vegas 36 3B CA-coast Los Angeles 3 4 4 4 27 3C San Francisco 38 4A Baltimore 7 4 4 4 29 4B Albuquerque 1 2 2 2 110 4C Seattle 311 5 5A Chicago 7 4 4 4 212 5 5B Denver 4 2 2 2 113 6 6A Minneapolis 314 6 6B Helena, MT 1 2 2 2 115 7 Duluth, MN 116 8 Fairbanks, AK 1

Total 50 25 25 25 12

Suitability of Prospective Site• Optimal

• Disaggregation of loads (as specified in energy conservation codes for metering)

• Or, at least all lighting and receptacle loads on dedicated panels

• Good • 90% of all lighting and receptacle loads are on dedicated panels

• Panels with receptacle and lighting loads are 90% dedicated

• Acceptable• 80% of all lighting and receptacle loads are on dedicated panels

• Panels with receptacle and lighting loads are 80% dedicated

• Other factors: Building size, service voltage, in-house transformers, metering resources required, primary energy sources for heating, cooling, and hot water

11

Site Monitoring Options

• Site monitoring options depend on project resources and on selected monitoring sites.

• Four options:• Monitor all loads, take spot measurements on transformers for harmonics and on

branch circuits for loading, obtain detailed service data (power quality and reliability and voltage stability)

• Monitor all loads

• Monitor lighting and receptacle loads

• Monitor receptacle (or lighting) load

12

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Sample Monitoring Locations in BuildingEx. 1: Monitoring Optimal Site with Load Separation

13

Elevator

Util.

Tx

480Y/277V

secondary

Interior Lighting

Exterior Lighting

Receptacle Loads

Mechanical Loads (Non-HVAC )

EV Charging Stations

HVAC Loads

Ex. 2 Optimal Site Ex. 3 Acceptable Site 14

15

Lt/M

c

Tx

P/M

c

Me

ch

Me

ch

Pw

er

Tx

Me

ch

Pw

er

Tx

Me

ch

Pw

er

Tx

Pw

er

P/M

c

Me

ch

Pw

er

Me

ch

Lt/M

c

Lig

ht

AT

S

Elevator

1st Floor

2nd Floor

3rd Floor

Util.

Tx Generator

Building Monitoring Locations

Ex. 4 Monitoring in a building which fails to meet “optimal” or “good” criteria

TEAM ROLL CALL: WHAT DO YOU THINK?

Project Technical Panel:

Mark Hilbert? Robert Arno? Mark Early?

Brian Liebel/Mark Lien?

Project Sponsors:

Michael Berthelsen? Brett Garrett? Lou Galante?

Dean Hansen? Kane Howard? Michael Hughes? Jim Jackson? Paul Kempf? Brian Meyers? Bob Wajnryb? Bob Yanniello?

Anyone else?

Mike Anthony? Jim Harvey? Richard Robben?