Print Page   |   Contact Us   |   Sign In   |   Join
IAEI Magazine
Blog Home All Blogs
Search all posts for:   

 

View all (1101) posts »
 

Proposed Changes for the 2002 NEC, Part 2

Posted By Philip Cox, Friday, September 01, 2000
Updated: Tuesday, February 12, 2013

This is the second part of a summary of proposed changes for the 2002 National Electrical Code® acted on by NEC Code Making Panels in January 2000. Proposals submitted to change the 2002 Code are included in the NEC Report on Proposals. That document is available from the National Fire Protection Association. Those who wish to make comments on actions taken by the code making panels must submit them to NFPA. They must be received by NFPA no later than 5:00 p.m. EDST, Friday, October 27, 2000. Blank forms for those comments are available from NFPA. They are also included in the ROP and can be downloaded from the NFPA web site. The address iswww.nfpa.org. Action will be taken in December 2000 by the 20 NEC Code Making Panels on public comments submitted and the results of panel actions will be published by NFPA in the NEC Report on Comments.

210-52(c)(5). Receptacle Outlet Location.
Proposal No. 2-172:
The term "appliance garages” has been added to the last sentence. This change clarifies that a receptacle installed inside an "appliance garage” does not count as the required outlet. An "appliance garage” is understood to be an enclosed area on the countertop where an appliance can be stored and hidden from view when not in use.

210-52(c)(5). Exception.
Proposal No. 2-175:
The second sentence of the Exception has been revised to read, "Receptacles mounted below a countertop that extends more than 6 in. (153 mm) beyond its support base, shall be located so that they are not more than 6 in. (153 mm) from the outside edge of the countertop.”

This change will permit the mounting of receptacles to the underside of extended countertops, provided the receptacles are within 6 inches of the outside edge of the countertop.

210-52(g). Basements and Garages.
Proposal No. 2-196:
The last sentence has been changed to read, "Where a portion of the basement is finished into one or more habitable rooms, each separate unfinished portion shall have a receptacle outlet installed in accordance with this section.”

This makes it clear that any unfinished portion of the basement, when separated by a finished portion, will have to have a receptacle outlet installed.

210-70(a)(2). Additional Locations.
Proposal No. 2-226(a):
210-70(a)(2) has been restructured for clarity and the last sentence has been revised to become 210-70(a)(2)c and reads, "c. Where one or more lighting outlet(s) are installed for interior stairways, there shall be a wall switch at each floor level, and landing level that includes an entry way, to control the lighting outlet(s) where the stairway between floor levels has six risers or more.”

This change in 210-70(a)(2)c will require a switch at an intermediate landing that has an entry way as well as at each floor level. In addition, the word "step” was changed to "riser” to conform with the accepted terms for the elements of a stairway.

Table 220-36.Optional Method—Permitted Load Calculations for Service and Feeder Conductors for New Restaurants.
Proposals Nos.2-304 and 2-305: Table 220-36 on the optional method for calculation of service and feeder conductors for new restaurants has been changed to reduce the break points from six to four and avoids the problem of adding load and reducing switch sizes, which the existing table would allow in isolated cases.

Article 225 – Outside Branch Circuits and Feeders:

225-26: Vegetation as Support.
Proposal No. 4-16:
This section was revised to read: "225.26. Vegetation as Support. Vegetation, such as trees, shall be permitted only for the support of temporary wiring, as covered in Article 305.” The title was expanded by adding the words "as support.” The wording "overhead conductor spans” at the end of the sentence was replaced with "temporary wiring, as covered in Article 305.” The exception was deleted as the concept of temporary wiring is included in the revised section.

225-30: Number of Supplies.
Proposal No. 4-17a:
The first sentence of the section was modified by adding the wording "additional” and "that is on the load side of the service disconnecting means.” It will now read: "Where more than one building or other structure is on the same property and under single management, each additional building or other structure served, that is on the load side of the service disconnecting means, shall be supplied by one feeder or branch circuit unless permitted in (a) through (e).” The revised wording adds clarity to the general rule covering the number of supplies permitted for multiple buildings or structures. The additional building or structure covered by this section are those supplied by conductors on the load side of the service disconnecting means.

225-30(a)(4).
Proposal No. 4-18a:
The word "optional” was deleted from 225-30(a)(4) and will now read: "(4) Standby systems.” This change should eliminate any potential confusion regarding standby systems being permitted under this section.

225-50. Supervised Installations. Proposal No. 4-39:A new section was added to describe conditions under which over 600 volt installations can be considered as supervised installations. The proposal was submitted as a new 225-48, but was renumbered by action on Proposal 4-40b.

225-51. Sizing of Outdoor Circuits.
Proposal No. 4-40b:
This new section has been added to include general rules for sizing of outdoor branch circuit and feeder conductors in over 600 volt installations. It also includes provisions for the sizing of conductors rated over 600 volt in supervised installations described in new 225-50. Conductors in supervised installations are permitted to be determined by qualified persons under engineering supervision.

Article 230 – Services

230-70(a). Location.
Proposal No. 4-107a:
This section was restructured and revised to better describe the required location of a building service disconnecting means and to clarify that a remote control actuator is not recognized as the required disconnecting means.

Article 240 – Overcurrent Protection

240-21(c). Transformer Secondary Conductors.
Proposal No. 10-34:
The title of subdivision (3) was revised to read "Industrial Installation” and a new subdivision (6) entitled "Secondary Conductors Not Over 25 ft Long” was added. The change more clearly identified the title of (3) to reflect the restriction to industrial installation and the new (6) provides a general 25 ft tap rule for transformers.

240-33. Vertical Position.
Proposal No. 10-46:
The wording "unless that is shown to be impracticable” was added to the end of the first sentence. This change addresses the conditions where circuit breaker enclosures cannot be mounted in the vertical position.

240-83(d). Used as Switches.
Proposal No. 10-63:
New wording has been added to this section to require circuit breakers used as switches for high intensity discharge lighting to be marked "HID.”

240-86. Series Ratings.
Proposal No. 10-67:
This section has been revised to add a provision for a line-side current-limiting device to be selected under engineering supervision to protect load side circuit breakers that have a lower interrupting rating than the available fault current on the circuit.

240-100(a).
Proposal No. 10-77:
The main rule covering overcurrent protection for over 600 volt feeders and branch circuits has been revised to provide examples of items to consider when designing the overcurrent protection to be at a location other than at the point where the conductor receives its supply. The design for overcurrent protection to be at an alternate location is required to be done under engineering supervision.

Article 250 – Grounding:

250-2(a). Grounding of Electrical Systems.
Proposal No. 5-60:The wording "required to be” was deleted from 250-2(a). This action should clarify that grounding rules must be followed whether systems are grounded because they are required to be, or if they are grounded by choice.

250-30(a)(2).
Proposal No. 5-101:
A new paragraph has been added to 250-30(a)(2) to permit a grounding electrode conductor of a separately derived system to be connected to a grounding electrode conductor that extends through a building. This change permits an alternate method of grounding separately derived systems where effectively grounded building steel or grounded metal water pipe is not near the separately derived system.

250-32(f). Grounding Electrode Conductor.
Proposal No. 5-123:
The title of 250-32(f) was amended by adding the word "”electrode”" and the reference to the table has been changed from Table 250-122 to read Table 250-66. This modification changes the sizing requirement for the grounding conductor at the second building or structure to that based on Section 250-66. In addition, the term for this conductor is no longer a "”grounding conductor,”" but is a "”grounding electrode conductor.”"

250-36(g). Equipment Bonding Jumper Size.
Proposal No. 5-134:
A new 250-36(g) has been added to provide equipment bonding sizing requirements for high-impedance grounded neutral systems.

250-50. Grounding Electrode System. Proposal No. 5-134a:This section has been revised to read: "”Grounding Electrode System. If available on the premise at each building or structure served, each item in 250-52(a)(1) through (a)(6) shall be bonded together to form the grounding electrode system. Where none of these electrodes is available, one or more of the electrodes specified in 250-52(a)(4) through (a)(7) shall be used.”"

This revised section includes requirements related to the grounding electrode system and correlates with the revised 250-52 and the new 250-53. The reference to "”made electrodes”" was deleted from this section.

250-52. Grounding Electrodes. Proposal No. 5-162(a):This section was revised by changing the title to "”Grounding Electrodes”" and was restructured to include two subheadings, "”(a) Electrodes Permitted for Grounding”" and "”(b) Electrodes not Permitted for Grounding.”" This section describes electrodes that are permitted for grounding and includes those that were previously described as "”made and other electrodes.”" The reference to made electrodes has been deleted. The change in this section, the amended 250-50, and the new 250-53 should help make it easier to understand the application of those respective rules.

250-53. Grounding Electrode System Installation.
Proposal No. 5-171a:
A new section has been added to cover installation requirements for grounding electrode systems. This section includes much of the material in Sections 250-50 and 250-52 of the 1999 NEC. Placing installation requirements for all grounding electrodes in one location will make it much easier for Code users to follow.

250-102(e). Installation.
Proposal No. 5-212:
A new sentence was added to permit an equipment bonding jumper to be longer than 6 feet where used to bond or ground metal raceways and elbows at utility poles.

250-104(a). General.
Proposal Nos. 5-219, 5-220, and 5-221:
The word "”interior”" has been deleted and the word "”installed in or attached to a building or structure”" were added in 250-104(e) (1), (2), and (3). This change clarifies the fact that piping installed inside or outside and attached to the building or structure is required to be bonded.

250-104(b). Metal Gas Piping.
Proposal No. 5-229:
The text in 250-104(b), which was extracted material from NFPA 54 for bonding metal gas piping systems, was deleted.

250-104(c). Other Metal Piping Systems. Proposal No. 5-238:The term "”interior”" was deleted and the wording "”installed in or attached to a building or structure”" was added. Other piping located inside or on the exterior and attached to the building or structure is now required to be bonded.

250-104(d). Structural Steel.
Proposal No. 5-240:
The term "”interior”" in the first sentence was deleted. This change clarifies that structural steel whether interior or exterior that is not intentionally grounded and interconnected to form a building frame must be bonded where it is likely to become energized.

250-118(11).
Proposal No. 5-254:
The wording "”the smooth or corrugated”" was added before "”Type MC cable to clarify that only the sheaths of smooth or corrugated tube-type MC cable assemblies are suitable for grounding.

250-146(a). Surface Mounted Box.
Proposal No. 5-282:
The wording "”or at”" in the first sentence was deleted. This change will permit only surface mounted boxes to be used for direct metal to metal contact between the receptacle yoke and the box as a means of grounding receptacles. This reverses the allowance granted for boxes mounted "”at the surface”" in the 1999 NEC to be acceptable for grounding receptacles.

250-184(d).
Proposal No. 5-302:
A new 250-184(d) has been added to cover rules on the size and grounding of the neutral and limits the maximum distance permitted between adjacent grounding electrodes on solidly grounded neutral systems to 400 meters.

Article 285 – Transient Voltage Surge Suppressors (TVSS)

Article 285.
Proposal No. 5-316:
A new Article 285 was added to requirements for installations of Transient Voltage Surge Suppressors (TVSS). Transient voltage surge suppressors are widely used as part of electrical systems in areas covered by the National Electrical Code but are not directly addressed by the Code.

Chapter 3 Articles

General Changes in Chapter 3:
Considerable work has been done by task groups to continue improving the Code and to make it even more user friendly. Chapter Three of the NEC was included in the task group work and several recommendations were made. The NEC Technical Correlating Committee and Code Making Panels affected by this work took action on task group recommendations and some of those actions are as follows:

Reformatting:Many Chapter 3 articles have been rewritten and reformatted to have similar structure and to comply with the NEC Style Manual. A more uniform method of numbering sections within each article will be used. As an example, the first section in each article is designated for the scope of that article (318-1, 336-1, etc). The second section is for definitions used in that article. "”Uses Permitted”" will have the same extension or section identifier in each applicable article (336-10, 345-10, etc).

Renumbering:Many Chapter 3 articles will be renumbered at the end of the processing of the 2002 NEC. This change includes a grouping of cable and raceway articles in a more logical manner.

Relocation:Some Chapter 3 articles are being relocated to other chapters because the content and scope of those articles are more appropriate for those chapters. As an example of relocation, Article 384, Switchboards and Panelboards, will be moved to Chapter 4 and renumbered.

Article 300 – Wiring Methods and Materials

300-4(d), Exception No. 3.
Proposal No. 3-30:
Exception No. 3 which provides that steel plates, sleeves, and similar protection of cables and raceways installed parallel to framing members are not required in mobile homes and recreational vehicles has been deleted. Mobile homes and RVs will be required to comply with the same rules on spacing in this section as applied to other types of buildings.

300-7(a). Sealing.
Proposal No. 3-61:
The wording in 300-7(a) requiring a seal for raceways and sleeving for cables against the flow of warm air within the raceway or sleeving to a colder section of the raceway or cable to prevent condensation has been revised. Wording has been added to specifically identify the passing of a raceway or cable from the interior to the exterior of a building and the wording "”and where there is a known condensation problem”" has been added.

300-11(c). Cables Not Used as Means of Support.
Proposal No. 3-73:
A new 300-11(c), entitled "”Cables Not Used as Means of Support”" has been added to clarify that cable wiring methods are not to be used as support for other materials and equipment. The present Code covers restrictions on the use of raceways for support of cables, other raceways, or other equipment, but does not specifically prohibit cable from being used in that fashion. It is not uncommon to find one cable installed and supported and others attached to it rather than having individual supports. This new subsection clearly prohibits the use of cable wiring methods as a means of support for other items.

300-22(c)(1) Exception.
Proposal No. 3-99:
The exception that permitted liquidtight flexible metal conduit in lengths not exceeding six feet in spaces used for environmental air has been deleted. The reference to "”single lengths not exceeding 6 ft (1.83 m)”" could have been misinterpreted to permit multiple runs of liquidtight flexible metal conduit in "”other space used for environmental air”" which does not appear to be the intent of the exception.

Article 305 – Temporary Wiring

Article 305. Temporary Wiring.
Proposal No. 3-141:
Article 305 has been re-located to Chapter 5 and will be renumbered accordingly. This article is more appropriate for Chapter 5 – Special Occupancies. CMP-3 will retain the responsibility of the relocated article.

305-3(b).
Proposal No. 3-124:
The provision that allows holiday decorative and similar lighting to be used for a period not longer than 90 days has been amended to provide for such use for more than 90 days where it is provided with arc-fault circuit-interrupter protection. It is extremely difficult to enforce the 90-day rule on this type of installation. Those installations may be de-energized for periods of time and/or redesigned and it is claimed that it constitutes a new 90 day period. The use of AFCIs with those circuits will provide another level of protection for those installations.

305-6(a) Exception No. 2. Proposal No. 3-138a:
The exception that permitted an assured equipment grounding conductor program to be used instead of using ground fault circuit interrupters for personnel in industrial establishments under certain conditions has been deleted. The record of performance of GFCIs in the protection of personnel justifies the use of those devices in the areas exempted by the exception.

Article 310 – Conductors for General Wiring

310-8(d). Locations Exposed to Direct Sunlight. Proposal 6-14a:
The text has been revised to clarify that conductors and cables are required to be "”listed for sunlight resistance”" or "”listed and marked for sunlight resistant”" where they are exposed to the direct rays of the sun.

310-15(b)(2)(a), Exception No. 5. Proposal 6-67:
A new exception has been added that will permit Type AC cable and MC cable without an overall outer jacket to be bundled without having to apply adjustment factors. Certain conditions must be met in order to apply the new exception.

Table 310-22.Ampacities of Two or Three Insulated Conductors, Rated 0 through 2000 Volts, Within an Overall Covering (Multiconductor Cable), in Raceway in Free Air Based on Ambient Air Temperature of 30EC (86EF). Proposal 6-6:
Table B-310-1 in Appendix B to Article 310 has been relocated as Table 310-21. This change locates the table within the requirements of the Code, enabling it to be used without engineering supervision

Article 318 – Cable Trays

318-3. Uses Permitted. Proposal No. 8-15:
A new sentence has been added to read, "”Cable tray installations shall be permitted to be used for feeder circuits, branch circuits, communications circuits, control circuits and signaling circuits.”" This additional wording provides a better description of permitted uses of cable trays.

318-3. Uses Permitted. Proposal No. 8-31:
A new sentence has been added to read, "”Cable trays and their associated fittings shall be identified for the intended use.”" This action provides an important focus on the consideration of cable trays as to their design and intended use so that they are installed and used properly.

318-3(e). Nonmetallic Cable Tray. Proposal No. 8-25a:
The wording in 318-3(e) has been revised by adding "”In addition to the uses permitted elsewhere in Article 318,”" at the beginning of the section. This change is to clarify that nonmetallic cable tray is permitted for purposes other than voltage isolation and corrosive areas.

318-6(c). Supports. Proposal No. 8-56:
A new second paragraph has been added to this section to read, "”Cable trays shall be supported at intervals in accordance with the installation instructions.”" Support requirements have not previously been specified in this section.

318-6(j). Raceway, Cables, and Boxes Supported from Cable Trays. Proposal No. 8-34:
The term "outlet” has been deleted from the title of 318-6(j) and the wording "”and conduit bodies”" added following the word "boxes”. The first sentence has been revised by deleting the word "outlet” and rewording it to read "”boxes and conduit bodies as covered in Section 370-1.”" The word "outlet” was deleted from the last sentence of the section and changed to "”boxes and conduit bodies…”" The reference to Article 370 was changed to Section 370-23. This action will permit other boxes than just outlet boxes to be supported beside or under the cable tray.

318-11(a). Multiconductor Cables. Proposal No. 8-52:
A reference to Section 310-15(a)(2) has been added to this section to provide guidance on the determination of allowable ampacity of multiconductor cables. Where cables are run out of the tray, consideration must be given to the rules for allowable ampacity for conductors in those locations.

318-11(b). Single Conductor Cables. Proposal No. 8-54:
A new first sentence has been added to read, "The allowable ampacity of single conductor cables, shall be as permitted by Section 310-15(a)(2).” This action is intended to address the condition where single conductor cables that leave the cable tray and are run in raceways or locations where the lower ampacity should apply. In those cases, the lower ampacity should be assigned to the cable to better assure that the entire length of the circuit will operate within safe limits.

Article 321 – Messenger Supported Wiring

321-4. Uses Not Permitted. Proposal No. 7-26:
The term "severe damage” was changed to "damage.” The distinction between "damage” and "severe damage” is not clearly defined. It is not desirable that this type of wiring be subject to damage, much less to whatever severe damage might be.

Article 330 – Mineral-Insulated, Metal-Sheathed Cable

330-80. Ampacity. Proposal No. 7-88:
A new Section 330-80 covering rules on the ampacity of Type MI cable has been added.

Article 333 – Armored Cable

333-7(b). Proposal No. 7-101:
This change permits up to 6′ of AC cable supplying lighting fixtures or other equipment in accessible ceilings to be unsupported. In the 1999 Code, this permission was limited to runs directly from an outlet box to the fixture or equipment.

Article 334 – Metal-Clad Cable

334-10(b). Unsupported Cables. Proposal 7-122:
This section was amended by deleting the wording "from an outlet.” The resulting wording is "…or where used in lengths not more than 1.8m (6 ft.) for connections within an accessible ceiling to lighting fixtures or equipment.”

334-22. Metallic Sheath. Proposal 7-126a:
A new second paragraph has been added to read, "A non-magnetic sheath or armor shall be used on single conductor Type MC.” The existing second paragraph is to become paragraph three.

Article 336 – Nonmetallic-Sheathed Cable: Types NM, NMC, and NMS

336-6(f). (To be 336-17). Grommets in Metal Studs. Proposal 7-158:
New text was added to make the language similar to that in 300-4(b)(1) for the protection of nonmetallic sheathed cable run through metal studs and to require that grommets used for cable protection in such studs be listed for that purpose. This text will become a new second paragraph 336-17 in the rewritten Article 336.

336-18, Exception No. 3. Proposal No. 7-169:
This exception was amended by deleting the wording "from an outlet” and the wording "shall be permitted without a support within 300 mm (12 in.) of termination.” This change to Article 336 permits up to 4 1/2′ of NM cable to be unsupported with accessible ceilings in the same manner as AC and MC.

Article 338 – Service-Entrance Cable: Types SE and USE

338-3(b). Grounded Conductor Not Insulated. Proposal No. 7-203:
This provision was revised to prohibit the use of bare grounded conductors, except as permitted by Section 250-140 for existing installations to ranges and clothes dryers. This eliminates the practice of using SE cable with a bare grounded conductor as the feeder to a second building.

338-4(a). Interior Installations. Proposal No. 7-205:
This change clarifies that type SE cable used for interior wiring must comply with the installation requirements of Parts A & B of Article 336, except Section 336-26 which deals with the ampacity of NM cable.

Article 340 – Power and Control Tray Cable: Type TC

340-8. Bends. Proposal No. 7-252a:
The wording in this section has been modified and expanded to read, "340-8. Bending Radius. Bends in Type TC cable shall be made so as not to damage the cable. For Type TC cable without metal shielding, the minimum bending radius shall be:

(1) Cables with an outside diameter of 1.000 inches or less- 4 times the overall diameter

(2) Cables with diameter of 1.001 to 2.000 inch – 5 times the overall diameter

(3) Cables with diameters of 2.001 inch and larger – 6 times the overall diameter

Type TC cables with metallic shielding shall have a minimum bending radius of not less than 12 times the cable overall diameter.”

This change in the minimum bending radius of Type TC cable reflects accepted industry standards.

Article 343 – Nonmetallic Underground Conduit with Conductors

343-1. Description. Proposal No. 8-77:
A provision has been added to this section to require the nonmetallic conduit used in this assembly to be listed. Conductors and cables used in this assembly are required by 343-14 to be listed.

Article 345 – Intermediate Metal Conduit

345-9(a). Threadless. Proposal No. 8-217:
A new sentence has been added to read, "Threadless couplings and connectors shall not be used on threaded conduit ends unless listed for the purpose.” This new provision will aid in the selection and use of threadless couplings on threaded ends of conduit as they will be required to be "listed for the purpose.”

345-12(b)(3). Proposal No. 8-222:
The wording "industrial machinery” has been replaced with "fixed equipment.” This clarifies that IMC can be dropped to fixed equipment where certain conditions are met and that it can be so used in more than just industrial locations.

Article 346 – Rigid Metal Conduit

346-1. Definition. Proposal No. 8-235:
The definition of rigid metal conduit has been revised to read, "Rigid Metal Conduit (RMC) is a threadable raceway of circular cross section designed for the physical protection and routing of conductors and cables and for use as an equipment grounding conductor when installed with its integral or associated coupling and appropriate fittings. RMC is generally made of steel (ferrous) with protective coatings or aluminum (nonferrous). Special use types are silicone bronze and stainless steel.”

346-17. Listing Requirements. Proposal No. 8-253:
A new section under construction specifications has been added to read, "Listing Requirements. Rigid Metal Conduit (RMC), factory elbows and couplings, and associated fittings shall be listed.”

The addition of this new provision is associated with the change made in the definition of RMC. Wording in the former definition in 346-1 that specified that RMC is a "…listed metal raceway…” was deleted. This new section not only specifies that the raceway be listed, but also other components used with it.

346-9(a). Threadless. Proposal No. 8-217:
A new sentence has been added to read, "Threadless couplings and connectors shall not be used on threaded conduit ends unless listed for the purpose.” This new provision will aid in the selection and use of threadless couplings on threaded ends of conduit as they will be required to be "listed for the purpose.”

346-10 and Table 346-10. Minimum Radius of Bends to Centerline of Conduit. Proposal No. 8-245:
The title of the table has been changed from "Radius of Conduit Bends” to "Minimum Radius of Bends to Centerline of Conduit.” The second sentence of the main paragraph has been changed to read, "The radius of the curve of any field bend to the centerline of the conduit shall not be less than indicated in Table 346-10.” This change shifts the focus of the radius from the inner edge of a field bend to the centerline of the conduit. It was pointed out that the measurement for conduit bending equipment for use in the field is based on the conduit centerline and not on the inner edge of the bend.

346-12(b)(3). Proposal No. 8-249:
The wording "stationary equipment or fixtures” has been replaced with "fixed equipment.” This clarifies that rigid metal conduit can be dropped to fixed equipment under certain conditions, but that it is not permitted for that use with stationary equipment or fixtures.

Article 347 – Rigid Nonmetallic Conduit

Table 347-9(A). Expansion Characteristics of PVC Rigid Nonmetallic Conduit Coefficient of Thermal Expansion… Proposal No. 8-267:
A new note has been added to this table to read, "Note: Add 30EF to the estimated temperature range when conduit is installed in direct sunlight to allow for radiant heating.” Rigid nonmetallic conduit exposed to direct sunlight is affected by the heating caused by that exposure and must be considered in the design for the expansion and contraction of this type of conduit.

Table 347-9(B). Proposal No. 8-269:
A new note has been added to this table to read, "Note: Add 30EF to the estimated temperature range when conduit is installed in direct sunlight to allow for radiant heating.” This new wording is the same as that added to Table 347-9(A).


Read more by Philip Cox

Tags:  Featured  September-October 2000 

Share |
Permalink | Comments (0)