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By Mike Holt, for EC&M Magazine
NOTE: There are no photos, images, or graphics included in this newlsetter.
Q11 Are receptacles required to be installed so that they can be removed without interrupting the power to any downstream receptacles?
A11 Continuity of the grounded neutral conductor of a multiwire branch circuit must not be interrupted by the removal of a wiring device. Therefore, the grounded neutral conductors must be spliced together, and a pigtail must be provided for the wiring device.
CAUTION: If the continuity of the grounded neutral conductor of a multiwire circuit is interrupted, the resultant over- or undervoltage could cause a fire and/or destruction of electrical equipment. Use graphic.
Note: The opening of the ungrounded conductors, or the grounded neutral conductor of a 2-wire circuit during the replacement of a device doesn't cause a safety hazard, so pigtailing of these conductors isn't required [110.14(B)].
Q12 Does the NEC restrict the placement of a light switch in a bathroom? What about pools, spas, and hot tub areas?
A12 Switches can be located next
to, but not within, a bathtub, hydromassage bathtub, or shower space [404.4 and 680.70
and 680.72]. According to 680.2, as hydromassage bathtub is a permanently installed bathtub
with a recirculating piping system designed to accept, circulate and discharge water after
Q13 Where there are two service disconnects installed on one side of the meter, can I run the service conductors through one disconnect to feed the second disconnect?
A13 Yes if adequate space is provided in the first disconnect [312.8]. Use the graphic we have on this.
Mike's Comment: This is the way I have my service installed. Photo.
Q14 If a single 20A, 125V laundry receptacle is located within six feet from the laundry tub, is GFCI protection?
A14 Yes, GFCI protection is required for all 15 and 20A, 125V receptacles located within an arc measurement of 6 ft from the dwelling unit laundry, utility, and wet bar sink [210.8(A)(7)].
Q15 Can I terminate two wires on a single-pole circuit breaker?
A15 Yes, if the terminal is identified for two conductors, either within the equipment instructions or on the terminal itself. It's my understanding that only Square D circuit breakers (15A, 20A, and 30A) are rated for two conductors.
Q16 What is minimum and maximum height for electrical equipment containing circuit breakers or switches?
A16 There is no minimum height
for switches and circuit breakers. However, 550.32(F) requires the service disconnecting
means enclosure for mobile and manufactured homes to be mounted a minimum of 2 ft above
the finished grade.
Q17 A three phase breaker is installed in a three phase panel, but the connected load is single phase. Is this a code violation?
Q18 Where is the system bonding jumper at a transformer required to be installed?
A18 The metal parts of the separately derived system must be bonded to the secondary grounded neutral terminal by the installation of a system bonding jumper. This bonding jumper ensures that dangerous voltage from a secondary ground fault can be quickly removed by opening the separately derived system circuit's overcurrent protection device [250.2(A)(3) and 250.30(A)(1)].
DANGER: During a ground fault, metal parts of electrical equipment, as well as metal piping and structural steel, will become and remain energized providing the potential for electric shock and fire if the system bonding jumper is not installed.
The system bonding jumper can be installed at the transformer, the first system disconnecting means, or any point in between the transformer and the first disconnecting means, but not at both locations.
CAUTION: Dangerous objectionable current will flow on conductive metal parts of electrical equipment as well as metal piping and structural steel, in violation of 250.6(A), if the system bonding jumper is installed at the transformer and the secondary system disconnecting means.
Q19 What size equipment grounding (bonding) conductor is required in each of four raceways for a 1600A, 120/208V, three-phase feeder?
A19 4/0 AWG. When circuit conductors are run in parallel [310.4], an equipment grounding (bonding) conductor must be installed with each parallel conductor set and it must be sized to the ampere rating of the circuit-protection device in accordance with Table 250.122.
Q20 Does the Code require an electric motor driven fire pump to be connected to a standby generator if a standby generator is installed on the premises?
A20 Power to fire pump motors must be supplied by a reliable source of power that has the capacity to carry the locked-rotor current of the fire pump motors, pressure maintenance pump motors, and the full-load current of any associated fire pump equipment. Reliable sources of power includes:
The determination of a reliable source
of power is subject to the approval of the authority having jurisdiction.
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