Jake Leahy s Electrical Code Connection. A look at Grounding and Bonding of Electrical Services Article Florida Building Code 5 th Edition

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1 Jake Leahy s Electrical Code Connection A look at Grounding and Bonding of Electrical Services Article Florida Building Code 5 th Edition

2 Wiring Integrity. Completed wiring installations shall be free from short circuits, ground faults, or any connections to ground other than as required or permitted elsewhere in this Code. The Code limits the connections to the grounded conductor (neutral) on the load side of the service disconnecting means. It cannot be bonded or connected to the equipment ground to limit its intended path and purpose.

3 Effective Ground-Fault Current Path. An intentionally constructed, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device or ground-fault detectors on high-impedance grounded systems.

4 Ground-Fault Current Path. An electrically conductive path from the point of a ground fault on a wiring system through normally non current-carrying conductors, equipment, or the earth to the electrical supply source. Ground Fault. An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally non current-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

5 IN: Examples of ground-fault current paths could consist of any combination of equipment grounding conductors, metallic raceways, metallic cable sheaths, electrical equipment, and any other electrically conductive material such as metal water and gas piping, steel framing members, stucco mesh, metal ducting, reinforcing steel, shields of communications cables, and the earth itself.

6 (5)Effective Ground-Fault Current Path. Electrical equipment and wiring and other electrically conductive material likely to become energized shall be installed in a manner that creates a low-impedance circuit facilitating the operation of the overcurrent device. It shall be capable of safely carrying the maximum groundfault current likely to be imposed on it from any point on the wiring system where a ground fault may occur to the electrical supply source. The earth shall not be considered as an effective ground-fault current path.

7 The grounded conductor shall not be connected to normally non current carrying metal parts of equipment, to equipment grounding conductor(s), or be reconnected to ground on the load side of the service disconnecting means except as otherwise permitted in article 250.

8 Grounded Conductor Brought to Service Equipment. Where an ac system operating at less than 1000 volts is grounded at any point, the grounded conductor(s) shall be routed with the ungrounded conductors to each service disconnecting means and shall be connected to each disconnecting means grounded conductor(s) terminal or bus. A main bonding jumper shall connect the grounded conductor(s) to each service disconnecting means enclosure. The grounded conductor(s) shall be installed in accordance with (C)(1) through (C)(3).

9 (1) Sizing for a Single Raceway. The grounded conductor shall not be smaller than the required grounding electrode conductor specified in Table but shall not be required to be larger than the largest ungrounded service-entrance phase conductor. In addition, for sets of ungrounded service-entrance conductors larger than 1100 kcmil copper or 1750 kcmil aluminum, the grounded conductor shall not be smaller than 12-1/2 percent of the circular mil area of the largest set of serviceentrance ungrounded conductor(s).

10 (2) Parallel Conductors in Two or More Raceways. If the ungrounded service-entrance conductors are installed in parallel in to or more raceways, the grounded conductor shall also be installed in parallel. The size of the grounded conductor in each raceway shall be based on the total circular mil area of the parallel ungrounded conductor in the raceway, as indicated in (C)(1), but not smaller than 1/0 AWG. (3) Delta-Connected Service. The grounded conductor of a 3-phase, 3-wire delta service shall have an ampacity not less than that of the ungrounded conductors.

11 Number of Neutrals

12 How many neutrals?

13 Ungrounded

14 Even FPL follows the rules

15 A 2000 ampere service has 8 #250 kcmil THHW cu conductors to make up each phase conductor. What size grounded (neutral) conductor is needed for the service? 250 Kcmil THHW Cu. = 255 amperes (310.16) 255 amperes X 8 = 2040 amperes (240.4 (C) ) 8 X 250 Kcmil = 2000 Kcmil (total for each phase) 2000 X.125 = 250 Kcmil for the grounded (neutral) conductor

16 A 400 ampere service has a #500 Kcmil THHW Cu. Conductor for each phase conductor. What is the minimum size grounded (neutral) conductor that can be run to the service? Per (C) (1) Table shows the size of the grounded conductor when the phase conductor is smaller than a #1750 Kcmil Cu. conductor. #500 Kcmil Cu. phase conductor = 1/0 Cu. Grounded conductor Per (C) (3) for Delta three wire three phase services the grounded conductor shall be the same size as the phase conductors and is only required to be brought to the first means of disconnect

17 Bonding Jumper, Main. Article 100. The connection between the grounded circuit conductor and the equipment grounding conductor at the service. Main bonding jumpers and system bonding jumpers shall not be smaller than the sizes shown in Table Where the supply conductors are larger than 1100 kcmil copper or 1750 kcmil aluminum, the bonding jumper shall have an area that is not less than 12-1/2 percent of the area of the largest phase conductor.

250.28(D)(2) Where a service consists of more than a single enclosure as permitted in 230.

18 250.28(D)(2) Where a service consists of more than a single enclosure as permitted in (A), the main bonding jumper for each enclosure shall be sized in accordance with (D)(1) based on the largest ungrounded service conductor serving that enclosure.

19 Main Bonding Jumper

21 NEUTRAL IMPROPERLY SIZED Delta Service

22 (A) Bonding of Equipment for Services. The normally non current-carrying metal parts of equipment indicated in (A)(1) and (A)(2) shall be bonded together. (1) All raceways, cable trays, cablebus framework, auxiliary gutters, or service cable armor or sheath that enclose, contain, or support service conductors, except as permitted in

23 (2) All enclosures containing service conductors, including meter fittings, boxes, or the like, interposed in the service raceway or armor. Course Note! These are the unprotected conductors from the utility, generator, or transformer. Unprotected meaning non-fused

(B) Bonding jumpers meeting the other requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts.

24 (B) Bonding jumpers meeting the other requirements of this article shall be used around impaired connections, such as reducing washers or oversized, concentric, or eccentric knockouts. Standard locknuts or bushings shall not be the only means for the bonding required by this section but shall be permitted to be installed to make a mechanical connection of the raceway(s). Electrical continuity at service equipment, service raceways, and service conductor enclosures shall be ensured by one of the following methods:

25 (1) Bonding equipment to the grounded service conductor in a manner provided in (2) Connections utilizing threaded couplings or threaded hubs on enclosures if made up wrench tight (3) Threadless couplings and connectors if made up tight for metal raceways and metal-clad cables (4) Other listed devices, such as bonding-type locknuts, bushings, or bushings with bonding jumpers

26 Meter Hub

27 Bonding Bushing

28 Bonding Screw

2/15/2015. Current will always try to return to its source. In order for there to be current, there must be a complete circuit

2/15/2015. Current will always try to return to its source. In order for there to be current, there must be a complete circuit Current will always try to return to its source In order for there to be current, there must be a complete circuit Current will take as many paths or circuits available to it to return to the source The