ROCKY MOUNTAIN CHAPTER IAEI
MARCH 17-18, 2011
1. Should gypsum board (drywall) be considered a “grounded surface” per Table 110.26(A)(1) condition 2?
Answer: No, Table 110.26(A)(1) definition for Condition 2 states: “Concrete, brick, or tile walls shall be considered as grounded”. Sheet rock walls do not fall into this definition. Basic rule is: If it is not prohibited then it is permitted.
2. Should carbon monoxide detectors be installed near the floor or the ceiling?
Answer: This is a question that is frequently asked. i.e., what is weight of CO relative to air. Some say CO device should be installed near the floor because CO is heavier than air, while others say it is lighter than air which means the CO device needs to be installed on or near the ceiling. The simple fact is the weight of CO is almost identical to air. Specifically, the molecular weight of CO is 28 grams per mole (g/mol), whereas the molecular weight of air is approximately 29 g/mol.
Because the weight of CO is almost identical to air and because HVAC systems will stir the CO and provide uniform concentrations throughout the building it doesn’t matter if the CO alarm or detector is installed on the wall or ceiling.
Furthermore in accordance with section 9.4.1.2 of NFPA 720 each alarm or detector shall be located on the wall, ceiling or other location as specified in the manufacturers published instructions that accompany the unit. R315.1 Carbon monoxide alarms.
For new construction, an approved carbon monoxide alarm shall be installed outside of each separate sleeping area in the immediate vicinity of the bedrooms in dwelling units within which fuel-fired appliances are installed and in dwelling units that have attached garages.
R315.2 Where required in existing dwellings.
Where work requiring a permit occurs in existing dwellings that have attached garages or in existing dwellings within which fuel-fired appliances exist, carbon monoxide alarms shall be provided in accordance with Section R315.1.
R315.3 Alarm requirements.
Single station carbon monoxide alarms shall be listed as complying with UL 2034 and shall be installed in accordance with this code and the manufacturer's installation instructions.
3. There are complaints that some vacuum cleaners are causing the AFCI breakers to trip. Is this a design problem of the breakers or a problem in the vacuum equipment?
Answer:
There have been some sporadic reports of combination AFCIs tripping with some vacuum cleaners initially when combination type devices were first used (and also earlier when branch feeder type devices were first used), but at UL we have not received any recent reports.
One problem may be that the supply house may have earlier vintage AFCIs on the shelf, while recently manufactured units usually have updated detection software to make them more resistant to this type of tripping. Going back to the supply house will typically just result in another AFCI with the same detection software installed, which does not fix the problem.
I would encourage you to file an unwanted tripping report with NEMA at www.afcisafety.org Manufacturers want to know and they want to resolve these issues.
The AFCI manufacturer must be contacted by the person having the problem and must be involved in the solution. The AFCI manufacturer will work with the party making the complaint to try to resolve the issue. An AFCI with updated software is usually provided. The manufacturers collect this information and use it to improve their products so that each generation can become more resistant to unwanted tripping.
4. Is it necessary to run a 4-wire lateral to a 3-phase fire pump?
Answer: For the 2011 NEC the service lateral is from the utility to the service point. From the service point to the service entrance conductors is the “service conductors underground” system. See new definitions in Article 100. Under both the 2008 NEC and 2011 NEC 250.24(C) states that if the supply system is less than 1000 Volts and is a grounded system, then the grounded circuit conductor (neutral) is required to be run to the service, including now the service lateral and the service conductors underground system, which would include any separate service to the fire pump. There are no modifications in Article 695 to change this. While the fire pump is a purely three phase load, the grounded circuit conductor is there to ensure the low impedance ground fault return path back to the source so the size would have to comply with 250.24(C)(1) and (2).
5. Is it permissible to use NM cable in an Assembly Occupancy of non-rated construction?
Answer: Yes
Reference: Section 518.4(B) Wiring Methods
6. Is it necessary to group the PV system AC-disconnect with the service disconnect?
Answer: No. Reference 690.14(D). It allows the inverter and associated disconnecting means to be mounted on a roof or where not readily accessible, therefore is is not required to group with the service disconnect. See also 690.56(B) which has marking requirements for the PV and service disconnecting means when in different locations.
7. Can a 50-amp receptacle be used on a 40-amp circuit?
Answer: Yes, Table 210.21(B)(3) allows either a 40 or 50 amp receptacle on a 40 amp circuit.
8. Do non-grounding replacement outlets need to be the tamperproof type?
Answer: NO 406.12 Exp#4
406.12 Tamper-Resistant Receptacles in Dwelling Units.
In all areas specified in 210.52, all nonlocking-type 125-volt, 15- and 20-ampere receptacles shall be listed tamper-resistant receptacles.
Exception:Receptacles in the following locations shall not be required to be tamper-resistant:
(1) Receptacles located more than 1.7 m (5½ ft) above the floor.
(2) Receptacles that are part of a luminaire or appliance.
(3) A single receptacle or a duplex receptacle for two appliances located within dedicated space for each appliance that, in normal use, is not easily moved from one place to another and that is cord-and-plug connected in accordance with 400.7(A)(6), (A)(7), or (A)(8).
(4) Nongrounding receptacles used for replacements as permitted in 406.4(D)(2)(a).
406.4 General Installation Requirements.
(D) Replacements. Replacement of receptacles shall comply with 406.4(D)(1) through (D)(6), as applicable.
(1) Grounding-Type Receptacles. Where a grounding means exists in the receptacle enclosure or an equipment grounding conductor is installed in accordance with 250.130(C), grounding-type receptacles shall be used and shall be connected to the equipment grounding conductor in accordance with 406.4(C) or 250.130(C).
(2) Non–Grounding-Type Receptacles. Where attachment to an equipment grounding conductor does not exist in the receptacle enclosure, the installation shall comply with (D)(2)(a), (D)(2)(b), or (D)(2)(c).
(a) A non–grounding-type receptacle(s) shall be permitted to be replaced with another non–grounding-type receptacle(s).
9. Can CFL or LED lamps be used in luminaries that are not listed for their use?
Answer: Yes, if they are UL Listed self ballasted lamps used in accordance with their Listing and the marking on the product. CFL’s are Listed under the product category Self Ballasted Lamps and Adapters (OOLR) is the category code and LED lamps are Listed under the category Lamps, Self Ballasted, LED Type category code (OOLV) both are located on page 262 in the white books.
The guide information on page 262 states for both categories state
These products are generally for use in indoor, dry locations unless additionally investigated and marked for applications such as damp locations (not directly exposed to water). Products investigated and marked for wet locations may have additional restrictions regarding use or orientation.
These products have been investigated for use in the smaller of a 6- or 8-in. diameter recessed luminaire, if they will physically fit, and are intended for use in totally enclosed, recessed luminaires unless marked and stated not for such use.
These products are not intended for use in emergency lighting equipment or exit fixtures where brightness is a factor.
10. Is a grounding electrode system required for a fire pump service?
Answer: Yes. Each service disconnect, including a separate fire pump service, must be connected to the grounding electrode system per 250.24(A) for the building or structure where the fire pump and fire pump service is located. Where there are multiple services, as typically would exist with a fire pump service, NEC 250.50 and 250.58 requires that all the grounding electrodes be connected in a common grounding electrode system and that each service be connected to that common system.
11. Is there any difference between a manufactured home and a mobile home?
Answer: Yes
Reference: 550.2 Definitions. Note: Mobile homes are defined as manufactured homes in the HUD regulations.
Note: For the purposes of NEC, and unless otherwise indicated, the term mobile home includes manufactured homes.
12. Are electronic ballasts considered non-linear loads?
Answer: Probably. See 220.61(C) Informational Note #2 and the second paragraph of the handbook explanation. See also 310.15(B)(5)(c). See definition of Nonlinear Load. “A load where the wave shape of the steady state current does not follow the wave shape of the applied voltage. Informational Note: Electronic equipment, electronic/electric-discharge lighting, adjustable-speed drive systems, and similar equipment may be nonlinear loads.
13. Does a neutral conductor larger than #4 AWG need a continuous white or grey color?
Answer: No, Article 200.6(B)(4) allows, at time of installation, white or gray marking at its termination
- Are the side screws of a receptacle required to be tightened when the conductors are stabbed in the back of the receptacle? The untightened screws decrease the clearance to the sides of the metal p-rings or boxes and cause a shock hazard.
Answer: NO
- Are Marijuana grow lights available that are listed for such use? Many are being rejected by the AHJ now and need third party field evaluations?
Answer: I’ve never been caught….I mean I don’t know anything about growing pot so I don’t know if there are specific lights that are Listed for growing pot, however, I have a friend who has a friend who knows a guy that tells me that allegedly these luminaires are typically chain hung HID luminaries and UL does List these types of HID luminaires under the category HIGH-INTENSITY-DISCHARGE SURFACE-MOUNTED LUMINAIRES (IEXT) located on page 163 in the White Book. I’m not sure of what configuration they are using that they are having trouble sourcing a Listed luminaire maybe they are not providing a lamp containment barrier I don’t know, but there are plenty of Listed luminaires out there that they can use.
- Is it necessary to consider the available fault current when installing a listed fire pump controller?
Answer: Yes. NEC 110.9 and 110.10 are general requirements that also apply to fire pump controllers. This is true if the fire pump controller is a service disconnect or if it is served by a feeder. The AIC of the overcurrent interrupting device must be greater than the available short circuit current and the SCCR of the fire pump controller assembly must be greater than the available short circuit current.
17. Could the GEC connected to the PV roof arrays draw lightning to the PV arrays?
Answer: Yes
Reference: 690.47
Note: The GEC would be the path for over voltages caused by lightning surges to return to the earth. It is very possible that the PV system itself would attract lightning which is one of the purposes of installing a grounding electrode system along with keeping the DC at an equal potential with earth. Section 690.47 requires a Grounding Electrode System because typically inverters have isolation between the ac and dc circuits. The two grounding systems are to be bonded together or have a common grounding electrode so that all ac and dc grounded circuit conductors and equipment grounding conductors have the same near-zero potential to earth.
18. What written warnings are needed for the flash protection requirement of NEC 110.16 and how will the electrician know the correct PPE to be worn?
Answer: The NEC® requirement is to mark that an arc flash hazard exists. No requirement exists within the NEC to mark the equipment so as to provide instruction to the electrician as to what PPE is to be worn. NFPA 70E (2009) 130.3(C) requires that equipment be field marked with a label containing the available incident energy or the required level of PPE.
19. Can three separate breakers be used for multi-wire branch circuits?
Answer: Yes, if installed according to Article 240.15(B)(1) with an “identified handle tie”.
210.4(B), 240.15(B)(1)
20. Will Manufactures design all-in-one service equipment to accept line side PV connections which cannot be accomplished now without voiding the listing?
Answer: Making that line side tap doesn’t necessarily void the standard listing. If you were to use a manufacturer listed kit then it would be appropriate. If you did a field modification you may need to get a field evaluation done by a third party approved listing lab. There will be I’m sure with the renewed energy challenges that there will be manufacturers making available this type of equipment.
21. Are there any “open splice connectors” listed for new work than can be buried in a wall or ceiling?
Answer: I am not sure what an open splice connector is, I assume one that doesn’t have to be in a box as permitted in 300.15(H ) and 334.40(B ) which states (B) Devices of Insulating Material. Switch, outlet, and tap devices of insulating material shall be permitted to be used without boxes in exposed cable wiring and for rewiring in existing buildings where the cable is concealed and fished.
Openings in such devices shall form a close fit around the outer covering of the cable, and the device shall fully enclose the part of the cable from which any part of the covering has been removed. Where connections to conductors are by binding-screw terminals, there shall be available as many terminals as conductors.
These devices are Listed as Non metallic Cable Interconnectors (QAAV), located on page 286. The guide information states These interconnectors are intended for use in exposed or concealed locations in accordance with the following Articles of ANSI/NFPA 70, ‘‘National Electrical Code’’:
Article 545, Manufactured Buildings
Article 550, Mobile Homes, Manufactured Homes, and Mobile Home Parks
Article 551, Recreational Vehicles and Recreational Vehicle Parks