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2011 Changes to the NEC – 300.3
The following is an instructional page from our 2011 Changes to the NEC Textbook/DVD Package complete with graphics and video where applicable. As part of our on-going effort to provide free resources to help the industry, we will be sending this content as part of a series of newsletters. Each newsletter will feature pages taken directly from our textbooks. This can be a great training resource for your organization!
There are some important features in this text which help to highlight the changes that you should be aware of:
- Each Code section which contains a change includes a summary of the change, followed by a paraphrase of the NEC text affected by the change. Any specific change is denoted by underlined text and in the corresponding chapter color
- Graphics with green borders and 2011 CC icons next to the heading are graphics that contain a 2011 change; graphics without a green border or icon are graphics that support the concept being discussed, but nothing in the graphic was affected by a 2011 Code change.
300.3(C) Conductors of Different Systems
A new Informational Note was added addressing solar photovoltaic systems.
300.3 Conductors.
(C) Conductors of Different Systems.
(1) Mixing. Power conductors of alternating current and direct-current systems rated 600V or less can occupy the same raceway, cable, or enclosure if all conductors have an insulation voltage rating not less than the maximum circuit voltage. Figure 300–1
Figure 300-1
Note 1: See 725.136(A) on the limitations of mixing Class 2 and Class 3 circuit conductors with other circuits. Figure 300–2
Figure 300-2
Author’s Comments:
• Control, signal, and communications wiring must be separated from power and lighting circuits so the higher-voltage conductors don’t accidentally energize the control, signal, or communications wiring:
– CATV Coaxial Cable, 820.133(A).
– Class 1, Class 2, and Class 3 Control Circuits, 725.48 and 725.136(A).
– Communications Circuits, 800.133(A)(1)(c).
– Fire Alarm Circuits, 760.136(A).
– Instrumentation Tray Cable, 727.5.
– Sound Circuits, 640.9(C).
• A Class 2 circuit that’s been reclassified as a Class 1 circuit [725.130(A) Ex 2] can be installed with associated power conductors [725.48(B)(1)] if all conductors have an insulation voltage rating not less than the maximum circuit voltage [300.3(C)(1)].
Note 2: PV system conductors, both direct current and alternating current, are permitted to be installed in the same raceways, outlet and junction boxes, or similar fittings with each other, but they must be kept entirely independent of all other non-PV system wiring [690.4(B)]. Figure 300–3
Figure 300-3
ANALYSIS: Installers of power and lighting conductors, such as the typical residential or commercial electrician, may not know of the requirements found in Article 690. With the addition of this Informational Note, electricians that don’t spend time there can be made aware of the requirements of 690.4(B) should the need present itself.
Author’s Comment: PV system conductors, both direct current and alternating current, are permitted to be installed in the same raceways, outlet and junction boxes, or similar fittings with each other, but they must be kept entirely independent of all other non-PV system wiring [690.4(B)].
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2011 NEC Changes DVD Package |
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Don't let the scale of the code changes intimidate you, this package will get you up to speed on the most essential 2011 NEC changes quickly. The book is well-organized, easy to follow, and the full-color illustrations bring the material to life. The DVDs bring together a group of experts from the field to discuss the changes and how they apply in the real-world.
This program includes the following items:
- Changes to the NEC 2011 Textbook
- Changes to the NEC 2011 DVD 1 & 2 includes Articles 90 - 810
Product Code: 11CCDVD
Price: $198.00
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