Staff Analysis for Declaratory Statement Request DS2015-125

Issue:

The petitioner, Gary R. Beaumont, President, Beaumont Electric Co; Inc., seeks a Declaratory Statement concerning Voltage drop feeders & branch circuits.  Chapter 4 [CE], Section C405.7.3 Voltage Drop, 5th Edition (2014) Florida Building Code, Energy Conservation.

 

Background:

Petitioner is concerned with the increase in cost involved with the up-size of feeders, which is required to meet the FBC 2% voltage drop for feeders.  This in contrast to the 3% voltage drop required in the NEC. The petitioner is bidding a project, a new 160,000 sf warehouse where the 2% feeder voltage drop is estimated to add $50,000 or more to the cost for the larger copper feeders and conduit.

 

The petitioner understands that the 2014 FBC code was adopted from ASHRAE 90.1 section 8.4.1-2010.  Since then, ASHRAE has revised this code per Addendum c to standard ASHRAE 90.1-2013.  The Addendum c allows voltage drop for feeder and branch combined to be a maximum of 5% voltage drop total.  The petitioner believes the reasons given for this Addendum c revision were “reduced first costs in certain projects while remaining neutral on energy costs” and proposes the question.

 

“Can electrical engineers design commercial construction projects to allow feeders to have more than a 2% voltage drop, as long as the feeders and branch circuits combined shall be sized for a maximum of 5% voltage drop to meet the intent of FBC – Energy Conservation – 2014 – C405.7.4”?

 

The petitioner believes the financial benefit to the commercial projects would be huge with no change in energy costs.

 

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Reference Material:

 

5th Edition (2014) Florida Building Code, Energy Conservation

Chapter 4 [CE]


C405.7 Electrical power (Mandatory).

C405.7.1 Applicability.
This section applies to all building power distribution systems. The provisions for electrical distribution for all sections of this code are subject to the design conditions in ASHRAE Standard 90.1.

 

C405.7.3 Voltage drop.

C405.7.3.1 - Feeders and customer owned service conductors.

Feeder and customer owned service conductors shall be sized for a maximum voltage drop of 2 percent at design load.

 

C405.7.3.2 Branch circuits.

Branch circuit conductors shall be sized for a maximum voltage drop of 3 percent at design load.

 

ASHRAE 90.1-2010 (as referenced by the 5th Edition (2014) FBC, Energy Conservation

 

8.4       Mandatory Provisions

8.4.1    Voltage Drop

 

Exception: Feeder conductors and branch circuits that are dedicated to emergency services.

 

8.4.1.1 Feeders. Feeder conductors shall be sized for a maximum voltage drop of 2% at design load.

 

8.4.1.2 Branch Circuits. Branch circuit conductors shall be sized for a maximum voltage drop of 3% at design load.

 

2011 National Electrical Code (currently referenced in the 5th Edition (2014) FBC

 

Informational Note No. 4:  Conductors for branch circuits as defined in Article 100, sized to prevent a voltage drop exceeding 3 percent at the farthest outlet of power, heating, and lighting loads, or combinations of such loads, and where the maximum total voltage drop on both feeders and branch circuits to the farthest outlet does not exceed 5 percent, provide reasonable efficiency of operation.  See Information Note No. 2 of 215.2(A)(3) for voltage drop on feeder conductors.

 

5th Edition (2014) Florida Building Code, Building

 

SECTION 102 APPLICABILITY
[A] 102.1 General.
Where there is a conflict between a general requirement and a specific requirement, the specific requirement shall be applicable. Where, in any specific case, different sections of this code specify different materials, methods of construction or other requirements, the most restrictive shall govern.

 

[A] 102.4 Referenced codes and standards.
The codes and standards referenced in this code shall be considered part of the requirements of this code to the prescribed extent of each such reference and as further regulated in Sections 102.4.1 and 102.4.2.

[A] 102.4.1 Conflicts.
Where conflicts occur between provisions of this code and referenced codes and standards, the provisions of this code shall apply.

[A] 102.4.2 Provisions in referenced codes and standards.
Where the extent of the reference to a referenced code or standard includes subject matter that is within the scope of this code or the Florida Codes listed in Section 101.4, the provisions of this code or the Florida Codes listed in Section 101.4, as applicable, shall take precedence over the provisions in the referenced code or standard.

 

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Updated Edition of ASHRAE 90.1

 

ASHRAE 90.1-2013 – User’s Manual

8. Power

 

8.4.1 – Voltage Drop

 

The voltage drop through feeder conductors may not exceed 2% of the supply voltage. The voltage drop through branch circuit conductors may not exceed 3% of the supply voltage. A total voltage drop of 5% from service equipment to the load may not be used to demonstrate compliance in lieu of the independent feeder conductor and branch circuit conductor voltage drop allowances. In practice, these voltage drop limitations result in selecting conductors and conduits based in the practice described in Table 9 of the 2011 National Electrical Code® Handbook.

 

Addendum c to Standard 90.1-2013

 

Modify the standard as follows (I-P and SI units)

8.4       Mandatory Provisions

8.4.1    Voltage Drop. The conductors for feeders and branch circuits combined shall be sized for a maximum of 5% voltage drop total.

 

DCA09-DEC-269

 

Based on the 2007 FBC and the 2005 NEC

 

-       The Petitioner inquires about the feeder connector voltage drop allowed by the Code and, specifically, whether Section 13-413.AB.1.1, Florida Building Code, Building Volume (2007) intentionally limits the voltage drop to 2 percent as opposed to the more permissive provisions identified by the National Electrical Code within a “fine print note.”

 

-       The provisions adopted within Chapter 13 of the Code limit the voltage drop for feeders and customer-owned service conductors to 2 percent as design load.  The more permissive recommendation contained in the National Electrical Code, a referenced standard within the Florida Building Code, do not supersede the explicit provisions within Chapter 13.

 

 

 

 

 

 

 

 

 

 

 

 

 

Staff analysis

 

 

Question:

 

Can electrical engineers design commercial construction projects to allow feeders to have more than a 2% voltage drop, as long as the feeders and branch circuits combined shall be sized for a maximum of 5% voltage drop to meet the intent of FBC – Energy Conservation – 2014 – C405.7.4”

 

Answer: 

 

No.  As per Section C405.7.3.1 of the 5th Edition (2014) FBC, Energy Conservation, feeder and customer owned service conductor must be sized for a maximum voltage drop of 2 percent at design load.