Code Consistency Questions
1. A design shows two hospital standby generators with each feeding directly into a 1200ampere, 277/480-volt outdoor sectioned switchgear that contains overcurrent/disconnect devices in separate sections of each switchgear that partially feeds a hospital’s critical branch to a transfer switch, life safety branch to a transfer switch, an equipment system transfer switch, and a fire pump circuit to a transfer switch. Is this a Code compliant design?
Generator 1
Switchgear 1
Generator 2
Switchgear 2
Circuits to transfer switches
Section 517.26 requires compliance with Article 700, unless amended by the requirements in
Article 517. Section 700.9(B) has been clarified by adding new (5) permitting wiring from an emergency source of power to supply any combination of emergency, legally required, and optional loads as follows: (B) Wiring. Wiring of two or more emergency circuits supplied from the same source shall be permitted in the same raceway, cable, box, or cabinet. Wiring from an emergency source or emergency source distribution overcurrent protection to emergency loads shall be kept entirely independent of all other wiring and equipment, unless otherwise permitted in (1) through (5): (5) Wiring from an emergency source to supply any combination of emergency, legally required, or optional loads in accordance with (a), (b) and (c): a. From separate vertical switchboard sections, with or without a common bus, or from individual disconnects mounted in separate enclosures; b. The common bus or separate sections of the
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Page 2 of 6 switchboard or the individual enclosures shall be permitted to be supplied by single or multiple feeders without overcurrent protection at the source and Exception to (5)(b): Overcurrent protection shall be permitted at the source or for the equipment, provided the overcurrent protection is selectively coordinated with the down-stream overcurrent protection.; and c.
Legally required and optional standby circuits shall not originate from the same vertical switchboard section, panelboard enclosure, or individual disconnect enclosure as emergency circuits.
2. Where 17-foot deep piers are used under a pier and beam dwelling with each pier having contact with the earth for at least 14 feet and with four ½ -inch x 16-foot bars of reinforcing steel being placed in each pier, could a single connection to one pier with all four bars being connected to the grounding electrode conductor satisfy the requirements of 250.52(A)(3)?
Maybe, if the bars are tied together. See 250.52(A)(3) that states, “An electrode encased by at least 50 mm (2 in.) of concrete, located horizontally near the bottom or vertically, and within that portion of a concrete foundation or footing that is in direct contact with the earth, consisting of at least 6.0 m (20 ft) of one or more bare or zinc galvanized or other electrically conductive coated steel reinforcing bars or rods of not less than 13 mm (½ in.) in diameter, or consisting of at least 6.0 m (20 ft) of bare copper conductor not smaller than 4 AWG.
Reinforcing bars shall be permitted to be bonded together by the usual tie wires or other effective means. Where multiple concrete-encased electrodes are present at a building or structure, it shall be permissible to bond only one into the grounding electrode system.”
3. Are over 600-volt, nominal, circuit breakers that are a part of metal-enclosed power switchgear required to be individually locked in the open position, or as an alternative can a lockable drawout mechanism be utilized where the circuit breaker is installed in a drawout mechanism and the mechanism is capable of being locked in such a position that the mechanism cannot be moved into the connected position?
See 490.46 that states, “Circuit breakers shall be capable of being locked in the open position or, if they are installed in a drawout mechanism, that mechanism shall be capable of being locked in such a position that the mechanism cannot be moved into the connected position. In either case, the provision for locking shall remain in place with or without the lock.”
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Page 3 of 6
4. Is there any way to install 480-volt lighting circuits served by a 480-volt corner-grounded delta service inside a building or structure such as an enclosed sports stadium?
No, see new 210.6(D)(3) that states, “Luminaires powered from direct current systems where the luminaire contains a listed, dc-rated ballast that provides isolation between the dc power source and the lamp circuit and protection from electric shock when changing lamps.” New paragraph 3 was the result of a rejected proposal (2-31) and later accepted comment (2-20) that addresses florescent lighting in commercial and industrial buildings that can be powered directly with DC power from photovoltaic (PV) systems. This is called Photovoltaic-Assisted
Lighting (PAL) and was first demonstrated more than 20 years ago at a supermarket on Long
Island, NY. PAL systems can use standard electronic ballasts as these contain rectifiers and can work just as well on DC as AC power. The main advantages are efficiency and simplicity – no power conditioning is needed between the PV system and the luminaires. Ballasts installed in these systems as listed for DC use. AC ballasts operate best on DC if the DC voltage is near the rectifier (peak) value of the normal AC supply. For 277 AC ballasts, this peak voltage is
391V (with maximum of 430V at 110% of normal AC voltage). This also keeps currents low and reduces overall system costs. 210.6(D)(2) excludes luminaires for systems over 277V and thus making photovoltaic-assisted lighting systems using 277V AC ballasts impractical.
5. Is it permissible to power a power-limited fire alarm power source from a general use branch circuit or is a dedicated branch circuit required? Also, should such circuits be alternately served from a building’s emergency system?
1) A dedicated branch circuit is required based on 760.121(B) as follows: 760.121 Power
Sources for PLFA Circuits. (B) Branch Circuit. An individual branch circuit shall be required for the supply of the power source. This branch circuit shall not be supplied through ground-fault circuit interrupters or arc-fault circuit interrupters. 2) The alternate source of power for a fire alarm panel would depend upon the fire alarm system that is installed, the type of facility being protected, the ease of connection to the generator, and the possibility of battery backup as an alternate power source. NFPA 72 provides some very definite requirements for alternate generator power to supply a fire alarm panel. These requirements are as follows:
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Page 4 of 6
4.4.1.5 Secondary Power Supply.
4.4.1.5.1* Secondary Power Supply for Protected Premises Fire Alarm Systems. The secondary power supply shall consist of one of the following:
(1) A storage battery dedicated to the fire alarm system arranged in accordance with 4.4.1.8
(2) An automatic starting, engine-driven generator serving the dedicated branch circuit specified in 4.4.1.4.1 and arranged in accordance with 4.4.1.9.3.1 and storage batteries dedicated to the fire alarm system with 4 hours of capacity arranged in accordance with
4.4.1.8
4.4.1.5.2 Secondary Power Supply for Supervising Station Facilities.
4.4.1.5.2.1 The secondary power supply shall consist of one of the following: (1) Storage batteries dedicated to the supervising station equipment arranged in accordance with 4.4.1.8
(2) A dedicated branch circuit of an automatic-starting, engine-driven generator arranged in accordance with
4.4.1.9.3.2(A) and storage batteries dedicated to the supervising station equipment with 4 hours of capacity arranged in accordance with 4.4.1.8
(3) A dedicated branch circuit of multiple engine-driven generators, at least one of which is arranged for automatic starting in accordance with 4.4.1.9.3.2(A)
4.4.1.9 Engine-Driven Generators.
4.4.1.9.1 Application and Installation. The application and installation of engine-driven generators shall be as specified in 4.4.1.9.2 through 4.4.1.9.7.
4.4.1.9.2 Primary Power Supply. Engine-driven generators arranged as the primary supply shall be designed and installed in an approved manner.
4.4.1.9.3 Secondary Power Supplies.
4.4.1.9.3.1 Protected Premises.
(A) Engine-driven generators used to provide secondary power for a protected premises fire alarm system shall comply with NFPA110, Standard for Emergency and Standby Power
Systems , Chapter 4, requirements for a Type 10, Class 24, Level 1 System. Installation shall be in accordance with NFPA70, National Electrical Code , Article 700.
6. Where a single 30-ampere, 120/240-volt, single-phase circuit is installed for a combination washer/dryer in dwelling unit, is it also required to install a 20-ampere 120-volt, 20-ampere circuit as required by 210.11(C)(2) for the laundry? 2) Also, would the load of 1500-va be required to be added to the dwelling calculated service ampacity as required by 220.52(B)?
3) What would be the demand in va for a washer/dryer that requires a 30-ampere, 120/240volt, single-phase plug-and-cord connected circuit in a dwelling or would we just count the required 20-ampere laundry circuit at 1500 va and the separate dryer circuit at 5,000 va?
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Page 5 of 6
1) Yes – 210.52(F) establishes requirements for 125V, 15 and 20A receptacles in addition to others that may be installed. 2) Yes – 220.52(B) – This load is permitted to be included with the general lighting load and subject to demand factors. 3) The VA calculation is based on
220.52(A) for the small appliance branch which is 1500VA and based on 220.54 the separate dryer circuit would be 5000VA or the nameplate rating whichever is larger.
7. Are elevators in single family dwellings covered by the Inspection Department?
Yes, NEC 620 does not distinguish between commercial or residential installations. The
Administrative Code says DOL has jurisdiction over commercial installations and not single family.
8. Are joints or splices permitted in the equipment grounding conductors in pool deck boxes?
No, per 680.24(D) Grounding Terminals. Junction boxes, transformer enclosures, and groundfault circuit-interrupter enclosures connected to a conduit that extends directly to a forming shell or mounting bracket of a no-niche luminaire shall be provided with a number of grounding terminals that shall be no fewer than one more than the number of conduit entries.
9. I have a cord and plug connected condensate pump for the furnace located in a crawl space or unfinished basement. Does the receptacle for this pump have to be gfci protected?
Yes, 210.8 states (A) Dwelling Units. All 125-volt, single-phase, 15- and 20-ampere receptacles installed in the locations specified in (1) through (8) shall have ground-fault circuit-interrupter protection for personnel.
(4) Crawl spaces — at or below grade level
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Page 6 of 6
(5) Unfinished basements — for purposes of this section, unfinished basements are defined as portions or areas of the basement not intended as habitable rooms and limited to storage areas, work areas, and the like
Exception to (5): A receptacle supplying only a permanently installed fire alarm or burglar alarm system shall not be required to have ground-fault circuit-interrupter protection.
10. From what point, to what point, do you measure in order to determine if you have a storable pool.
From the top most rim of the pool at the surface to the lowest point in the bottom.
11. I have a house that was built before the code required outdoor receptacles on the front and/or the back of the house. If I add a room addition to this house am I now required to add an outdoor receptacle?
Yes, If the room addition affects only the footprint of the front of the house, an outdoor receptacle shall be added to the front; if the addition affects only the footprint of the back of the house then an outdoor receptacle shall be added to the back; if the addition affects the footprint of both the front and the back of the house then outdoor receptacle shall be added to the front and back.
ALSO
If a major interior rewire is done on an existing house that involves the front or back or both of the house at grade level; then outdoor receptacles shall also be added respectively.
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