FORM FOR COMMENT FOR 2008 NATIONAL ELECTRICAL CODE®
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LOG #
each proposal to a SINGLE section. NFPA must receive all submissions by
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Date Rec’d:
Electrical Code. Proposals received after 5:00 p.m. EST, Friday, October 20, 2006
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Date___October 19, 2006_____________Name_Dr. Robert H. Wills, P.E._______________Tel. No. _603-801-4749
Company _ INTERGRID, LLC
Street Address PO Box 48_City_ Temple State_NH _
Please Indicate Organization Represented (if any)___This issue is of interest to the Photovoltaic, Wind, and Fuel cell industries.
I represent the Solar Energy Industries Association on CMP-13__
1. (a) NFPA Document Title___National Electrical Code_ NFPA No. & Year___70 2008____
(b) Section/Paragraph ___210.6(D)________
2. Comment on Proposal No. (from ROP): _ 2-32 Log #2742 NEC-P02
3. Comment recommends: (check one) xxx new text X revised text deleted text
4. Comment (include proposed new or revised wording or identification of wording to be deleted): (Note: Proposed text should be in legislative format; i.e., use an underscore to denote wording to be inserted (inserted wording) and strike-through to denote wording to be deleted (deleted wording).
I request that the panel reconsider its reject vote with the following language substituted for that of the original proposal:
Add a Part (3) and Exception (3) to 210.6 (D) Branch-Circuit Voltage Limitations, 600 Volts Between Conductors so that the complete section reads as follows:
(D) 600 Volts Between Conductors
Circuits exceeding 277 volts, nominal, to ground and not exceeding 600 volts, nominal, between conductors shall be permitted to supply the following:
(1) The auxiliary equipment of electric-discharge lamps mounted in permanently installed luminaires (fixtures) where the luminaires (fixtures) are mounted by one of the following:
a. Not less than a height of 6.7 m (22 ft) on poles or similar structures for the illumination of outdoor areas such as highways, roads, bridges, athletic fields, or parking lots
b. Not less than a height of 5.5 m (18 ft) on other structures such as tunnels
(2) Cord-and-plug-connected or permanently connected utilization equipment other than luminaires (fixtures)
(3) Luminaires powered from direct current systems where the luminaire contains a listed, dc-rated ballast that provides isolation between the dc power source and the lamp circuit and protection from electric shock when changing lamps.
FPN: See 410.78 for auxiliary equipment limitations.
Exception No. 1 to (B), (C), and (D): For lamp holders of infrared industrial heating appliances as provided in 422.14.
Exception No. 2 to (B), (C), and (D): For railway properties as described in 110.19.
Exception No. 3 to (D): Luminaires in installations where conditions of maintenance and supervision ensure that only qualified persons service the building.
5. Statement of Problem and Substantiation for Comment: (Note: State the problem that your recommendation will resolve; give the specific reason for your Comment, including copies of tests, research papers, fire experience, etc. If more than 200 words, it may be abstracted for publication.) ___________________________
A/ The panel rejected previous submissions on this topic due to the following:
The recommendation proposed would allow a luminaire with up to 430V to be installed where it could be easily accessed for changing lamps, etc. This defeats the intent of the requirement, which is to require luminaires with voltage supplies higher than 277V to be limited to concrete installations as described in 210.6(D)(1). There is no substantiation to allow luminaires supplied from PV systems to be treated differently than luminaries’ power by AC line power.
1/ The requirements of Article 210.6(D) are intended to protect non-qualified persons from the risk of electric shock while changing lamps, etc.
2/Using listed electronic light ballasts that provide isolation between the AC or DC power source and the lamp circuit and protection against electric shock is an alternative means of achieving this intent.
3/ The proposed new language for 210.6(D)(3) would connect listed, dc-rated ballasts to dc circuits operating between 277 and 600V. Fluorescent lamp ballasts are listed under UL935, which tests for and protects against the potential for an electric shock when changing lamps. UL935 applies to both AC and DC-powered ballasts. UL1029 applies to high-intensity discharge ballasts and has similar provisions for preventing electric shock.
Four/ Most electronic ballasts can operate on AC and DC as the internal electronics convert incoming power to DC before inverting to lamp voltage. Many are listed for both AC and DC use. A ballast connected to a 277V ac nominal circuit will be subject to a 392V peak and a 431V peak at (+10%) ac high line. The internal DC bus of the ballast will be charged to the same (392Vdc) level whether the ballast is connected to 277Vac or 392Vdc. The lamp is then supplied via an isolated high-frequency inverter circuit. The voltages available in the ballast and the risk of electric shock when changing bulbs are identical.
5/ The potential risk to a person changing a ballast is a separate issue that is addressed by the new requirements of Article 410.73(G) requiring a ballast disconnect switch: “The luminaire will contain a disconnect means internal or external to itself or the luminaire will be cord and plug wired with UL rated hardware.” Ballast replacement is also an activity usually performed by qualified personnel.
Six/ Comments from luminaire manufacturers (in the 2005 ROP) in response to the changes in the 2005 code that excluded luminaires from operating at over 277V stated that this change was occurring without justification – no problems or cases of electric shock had been reported for lighting systems using at over 277V.
B/ The new exception (3) to 210.6(D) provides consistency between under 600V and over 600V requirements:
Article 210.6(E) (Over 600 Volts Between Conductors) states:
“Circuits exceeding 600 volts, nominal, between conductors shall be permitted to supply utilization equipment in installations where conditions of maintenance and supervision ensure that only qualified persons service the installation.”
This provision for over 600V between conductors is also appropriate for the voltage range 277 to 600V, where the general use of luminaires was prohibited in the 2005 code. This exception would allow the use of luminaires operating above 277V AC and DC where conditions of maintenance and supervision ensure that only qualified persons service the installation.
C/ Industry and Societal Impact
DC-assisted lighting systems supply rectified AC power to new and existing lighting installations. Additional energy is provided (directly via diode coupling) from DC sources such as photovoltaics, fuel cells, and wind generators.
DC lighting systems of this type have been researched and operating reliably for over 20 years. The first such system (a photovoltaic-assisted lighting system in a department store in Massachusetts) was installed by UMass Lowell and is still operating.
The change to the 2005 NEC to 210.6(D)(2) that excluded luminaires from supply voltages above 277V has (perhaps inadvertently) made DC-assisted lighting systems illegal, but DC-assisted lighting systems for commercial and industrial buildings have the potential to reduce US energy consumption significantly.
More than 100 billion square feet of commercial and industrial space in the USA is lit with fluorescent and HID lighting. Typical lighting density is 2 W/square foot (a total electric demand of about 200 GW – about 20% of the total generating capacity).
The advantages of these systems are:
1/ Efficiency – energy from the DC power source is used directly without conversion to AC and back to DC again
2/ Cost – the cost of inverters is eliminated
Three/ Interconnection barriers – there is no possibility of back-feeding the electric grid, so there are no interconnection issues.
Including this proposal or equivalent language is essential for preserving an existing, growing segment of the renewable-energy industry that can significantly reduce US energy demand. It is necessary for the future of our country.
6. Copyright Assignment
(a) x I am the author of the text or other material (such as illustrations and graphs) proposed in this Comment.
(b) □ Some or all of the text or other material proposed in this Comment was not authored by me. Its source is as follows: (please identify which material and provide complete information on its source)______________________________
____________________________________________________________________________________________________
At this moment, I grant and assign to the NFPA all and complete rights in copyright in this Comment and understand that I acquire no rights in any publication of NFPA in which this Comment in this or another similar or analogous form is used. Except to the extent that I do not have the authority to make an assignment in materials that I have identified in (b) above, I now warrant that I am the author of this Comment and have full power and authority to enter into this assignment.
Signature (Required) _,
Dr. Robert H. Wills, P.E.
President, Intergrid, LLC
Photovoltaics Alternate Rep for Solar Energy Industry Association, CMP-13
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