- Grounding electrode conductors and equipment bonding jumpers or conductors.
- Load management control conductors having overcurrent protection.
TABLE E3602.2 MINIMUM SERVICE LOAD CALCULATION [220.82(B) & (C)]
|LOADS AND PROCEDURE|
| 3 volt-amperes per square foot of floor area for general lighting |
and general use receptacle outlets.
| 1,500 volt-amperes multiplied by total number of 20-ampere-rated |
small appliance and laundry circuits.
| The nameplate volt-ampere rating of all fastened-in-place, |
permanently connected or dedicated circuit-supplied appliances such as
ranges, ovens, cooking units, clothes dryers not connected to the
laundry branch circuit and water heaters.
|Apply the following demand factors to the above subtotal:|
| The minimum subtotal for the loads above shall be 100 percent of |
the first 10,000 volt-amperes of the sum of the above loads plus 40
percent of any portion of the sum that is in excess of 10,000 volt-
|Plus the largest of the following:|
| One-hundred percent of the nameplate rating(s) of the air- |
conditioning and cooling equipment.
| One hundred percent of the nameplate rating(s) of the heat pump |
where a heat pump is used without any supplemental electric heating.
| One-hundred percent of the nameplate rating of the electric thermal |
storage and other heating systems where the usual load is
expected to be continuous at the full nameplate value. Systems
qualifying under this selection shall not be figured under any other
category in this table.
| One-hundred percent of nameplate rating of the heat pump com- |
pressor and sixty-five percent of the supplemental electric heating
load for central electric space-heating systems. If the heat pump
compressor is prevented from operating at the same time as the
supplementary heat, the compressor load does not need to be added
to the supplementary heat load for the total central electric space-
| Sixty-five percent of nameplate rating(s) of electric space-heating |
units if less than four separately controlled units.
| Forty percent of nameplate rating(s) of electric space-heating units |
of four or more separately controlled units.
| The minimum total load in amperes shall be the |
volt-ampere sum calculated above divided by 240 volts.
Exception: Two to six circuit breakers or sets of fuses shall be permitted as the overcurrent device to provide the overload protection. The sum of the ratings of the circuit breakers or fuses shall be permitted to exceed the ampacity of the service conductors, provided that the calculated load does not exceed the ampacity of the service conductors. [230.90(A) Exception No. 3]
TABLE E3603.4 GROUNDING ELECTRODE CONDUCTOR SIZEa, b, c, d, e, f
| SIZE OF LARGEST UNGROUNDED |
OR EQUIVALENT AREA FOR PARALLEL
| SIZE OF GROUNDING |
|Copper|| Aluminum or |
|Copper|| Aluminum or |
|2 or smaller||1/0 or smaller||8||6|
|1 or 1/0||2/0 or 3/0||6||4|
|2/0 or 3/0||4/0 or 250||4||2|
| Over 3/0 |
| Over 250 |
| Over 350 |
| Over 500 |
|a. If multiple sets of service-entrance conductors connect directly to a service drop, set of overhead service conductors, set of underground service conductors, or service lateral, the equivalent size of the largest service-entrance conductor shall be determined by the largest sum of the areas of the corresponding conductors of each set.|
|b. Where there are no service-entrance conductors, the grounding electrode conductor size shall be determined by the equivalent size of the largest service-entrance conductor required for the load to be served.|
|c. Where protected by a ferrous metal raceway, grounding electrode conductors shall be electrically bonded to the ferrous metal raceway at both ends. [250.64(E)(1)]|
|d. An 8 AWG grounding electrode conductor shall be protected with rigid metal conduit, intermediate metal conduit, rigid polyvinyl chloride (Type PVC) nonmetallic conduit, rigid thermosetting resin (Type RTRC) nonmetallic conduit, electrical metallic tubing or cable armor. [250.64(B)]|
|e. Where not protected, 6 AWG grounding electrode conductor shall closely follow a structural surface for physical protection. The supports shall be spaced not more than 24 inches on center and shall be within 12 inches of any enclosure or termination. [250.64(B)]|
|f. Where the sole grounding electrode system is a ground rod or pipe as covered in Section E3608.3, the grounding electrode conductor shall not be required to be larger than 6 AWG copper or 4 AWG aluminum. Where the sole grounding electrode system is the footing steel as covered in Section E3608.1.2, the grounding electrode conductor shall not be required to be larger than 4 AWG copper conductor. [250.66(A) and (B)]|
FIGURE E3604.1 CLEARANCES FROM BUILDING OPENINGS
- Conductors above a roof surface subject to pedestrian traffic shall have a vertical clearance from the roof surface in accordance with Section E3604.2.2. [230.24(A) Exception No. 1]
- Where the roof has a slope of 4 inches (102 mm) in 12 inches (305 mm), or greater, the minimum clearance shall be 3 feet (914 mm). [230.24(A) Exception No. 2]
- The minimum clearance above only the overhanging portion of the roof shall not be less than 18 inches (457 mm) where not more than 6 feet (1829 mm) of overhead service conductor length passes over 4 feet (1219 mm) or less of roof surface measured horizontally and such conductors are terminated at a through-the-roof raceway or approved support. [230.24(A) Exception No. 3]
- The requirement for maintaining the vertical clearance for a distance of 3 feet (914 mm) from the edge of the roof shall not apply to the final conductor span where the service drop is attached to the side of a building. [230.24(A) Exception No. 4]
- Where the voltage between conductors does not exceed 300 and the roof area is guarded or isolated, a reduction in clearance to 3 feet (914 mm) shall be permitted. [230.24(A) Exception No. 5]
FIGURE E3604.2.1 CLEARANCES FROM ROOFS
- For conductors supported on and cabled together with a grounded bare messenger wire, the minimum vertical clearance shall be 10 feet (3048 mm) at the electric service entrance to buildings, at the lowest point of the drip loop of the building electric entrance, and above areas or sidewalks accessed by pedestrians only. Such clearance shall be measured from final grade or other accessible surfaces.
- Twelve feet (3658 mm)—over residential property and driveways.
- Eighteen feet (5486 mm)—over public streets, alleys, roads or parking areas subject to truck traffic. [(230.24(B)(1), (2), and (4)]
1. A copper grounded conductor shall not be required to be insulated where it is:
1.1. In a raceway or part of a service cable assembly,
1.2. Directly buried in soil of suitable condition, or
1.3. Part of a cable assembly listed for direct burial without regard to soil conditions.
2. An aluminum or copper-clad aluminum grounded conductor shall not be required to be insulated where part of a cable or where identified for direct burial or utilization in underground raceways. (230.41 Exception)
- The conductors and cables shall be listed, or listed and marked, as being sunlight resistant.
- The conductors and cables are covered with insulating material, such as tape or sleeving, that is listed, or listed and marked, as being sunlight resistant. [310.10(D)]
Exception: Where it is impracticable to locate the service head or gooseneck above the point of attachment, the service head or gooseneck location shall be not more than 24 inches (610 mm) from the point of attachment. [230.54(C) Exception]
Exception: A grounding electrode shall not be required where only one branch circuit, including a multiwire branch circuit, supplies the building or structure and the branch circuit includes an equipment grounding conductor for grounding the noncurrent-carrying parts of all equipment. For the purposes of this section, a multiwire branch circuit shall be considered as a single branch circuit. [250.32(A) Exception]
Exception: Concrete-encased electrodes of existing buildings or structures shall not be required to be part of the grounding electrode system where the steel reinforcing bars or rods are not accessible for use without disturbing the concrete. (250.50 Exception)
Where the supplemental electrode is a rod, pipe or plate electrode in accordance with Section E3608.1.4 or E3608.1.5, that portion of the bonding jumper that is the sole connection to the supplemental grounding electrode shall not be required to be larger than 6 AWG copper or 4 AWG aluminum wire. [250.53(D) and (E)]
- One or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods not less than 1/2 inch (13 mm) in diameter, installed in one continuous 20-foot (6096 mm) length, or if in multiple pieces connected together by the usual steel tie wires, exothermic welding, welding, or other effective means to create a 20-foot (6096 mm) or greater length.
- A bare copper conductor not smaller than 4 AWG.
Where multiple concrete-encased electrodes are present at a building or structure, only one shall be required to be bonded into the grounding electrode system. [250.52(A)(3)]
- Grounding electrodes of pipe or conduit shall not be smaller than trade size 3/4 (metric designator 21) and, where of iron or steel, shall have the outer surface galvanized or otherwise metal-coated for corrosion protection.
- Rod-type grounding electrodes of stainless steel and copper or zinc-coated steel shall be at least 5/8 inch (15.9 mm) in diameter unless listed. [250.52(A)(5)]
- A rod, pipe, or plate electrode.
- A grounding electrode conductor.
- A grounded service-entrance conductor.
- A nonflexible grounded service raceway.
- A grounded service enclosure.
Exception: Where a single rod, pipe, or plate grounding electrode has a resistance to earth of 25 ohms or less, the supplemental electrode shall not be required. [250.53(A)(2) Exception]
- Raceways or service cable armor or sheath that enclose, contain, or support service conductors.
- Service enclosures containing service conductors, including meter fittings, and boxes, interposed in the service raceway or armor. [250.92(A)]
- It shall be accessible for connection and inspection.
- It shall consist of a set of terminals with the capacity for connection of not less than three intersystem bonding conductors.
- It shall not interfere with opening of the enclosure for a service, building or structure disconnecting means, or metering equipment.
- Where located at the service equipment, it shall be securely mounted and electrically connected to an enclosure for the service equipment, to the meter enclosure, or to an exposed nonflexible metallic service raceway, or shall be mounted at one of these enclosures and connected to the enclosure or to the grounding electrode conductor with a 6 AWG or larger copper conductor.
- Where located at the disconnecting means for a building or structure, it shall be securely mounted and electrically connected to the metallic enclosure for the building or structure disconnecting means, or shall be mounted at the disconnecting means and connected to the metallic enclosure or to the grounding electrode conductor with a 6 AWG or larger copper conductor.
- It shall be listed as grounding and bonding equipment. (250.94)
Exception: Splicing of the grounding electrode conductor by irreversible compression-type connectors listed as grounding and bonding equipment or by the exothermic welding process shall not be prohibited. [250.64(C)(1)]
Bare aluminum or copper-clad aluminum grounding electrode conductors shall not be used where in direct contact with masonry or the earth or where subject to corrosive conditions. Where used outside, aluminum or copper-clad aluminum grounding electrode conductors shall not be installed within 18 inches (457 mm) of the earth. [250.64(A)]
Where a raceway is used as protection for a grounding conductor, the installation shall comply with the requirements of Chapter 38. [250.64(E)(4)]
Exception: A wire-type equipment grounding conductor shall be permitted to serve as both an equipment grounding conductor and a grounding electrode conductor where installed in accordance with the applicable requirements for both the equipment grounding conductor and the grounding electrode conductor in Chapters 36 and 39. Where used as a grounding electrode conductor, the wire-type equipment grounding conductor shall be installed and arranged in a manner that will prevent objectionable current. [250.121 Exception, 250.6(A)]
- A pipe fitting, pipe plug or other approved device screwed into a pipe or pipe fitting.
- A listed bolted clamp of cast bronze or brass, or plain or malleable iron.
- For indoor communications purposes only, a listed sheet metal strap-type ground clamp having a rigid metal base that seats on the electrode and having a strap of such material and dimensions that it is not likely to stretch during or after installation.
- Other equally substantial approved means. (250.70)
Where interior metal water piping is used as a conductor to interconnect electrodes that are part of the grounding electrode system, such piping shall be located not more than 5 feet (1524 mm) from the point of entry into the building. [250.68(C)(1)]