Article 210 Branch Circuits
Article 250 Grounding
Article 408 Switchboards and Panelboards
Article 430 Motors, Motor Circuits and Controllers
Article 680 Swimming Pools, Fountains and Similar Installations
Volume One of the 2003 edition of the Fire Resistance Directory published by Underwriters Laboratories Inc. is also mentioned.
Location of disconnect for spas and hot tubs
Q: In the 1999 edition of the National Electrical Code there was a requirement for the disconnecting means for pools, spas and hot tubs to be located at least 5 feet from the inside walls of a pool, spa or hot tub. This requirement appeared in 680-12 of the 1999 NEC. The 2002 edition does not have any dimensions for the location of this switch. Does this omission allow a disconnect behind the skirt of a hot tub or allow the switch to be located less than 5 feet from a spa or hot tub?
A: You are correct in your statement that 680.12 no longer includes a specific location for the disconnecting means. This is the way 680.12 reads: “Maintenance Disconnecting Means. One or more means to disconnect all ungrounded conductors shall be provided for all utilization equipment other than lighting. Each means shall be accessible and within sight from its equipment.”
Although a maintenance disconnect switch may be located behind the skirt of a spa or hot tub, and may be required by the installation instructions provided by the manufacturer, at least one other disconnecting means is required by other parts of the Code.
Switching devices are required to be located at least 5 feet horizontally from the inside walls of a pool unless separated by a permanent barrier. In my opinion, the skirt of a hot tub or spa is a permanent barrier even though it can be removed for servicing the equipment.
Here are some of the rules that require an additional disconnecting means:
An emergency switch for spas and hot tubs is required by 680.41. This switch must be identified as an emergency disconnect and must stop the motor(s) in the circulation and jet systems when placed in the off position. It must be readily accessible, within sight and not located closer than 5 feet from the inside walls of the spa or hot tub. This rule applies to all occupancies except one-family dwellings.
A disconnecting means for motors is required by 430.102. This disconnect must be within sight (visible and not more than 50 feet away), and at least one disconnecting means for the motor must be readily accessible.
For motors rated more than 1/8 hp and not more than 2 hp, a general use switch with an Ampere rating that is at least twice the full load current of the motor can be used, or a general use snap switch that is suitable for use on AC circuits only can be used as the disconnecting means provided that the full load current of the motor does not exceed 80 percent of the Ampere rating of the switch. This information is in 430. 109(B) and (C).
In the absence of any manufacturer’s instructions that require a disconnect behind the skirt of the hot tub or spa, a single switch meeting the requirements of 430-109, located not less than 5 feet from the inside walls of the spa or hot tub, readily accessible, and identified as an emergency switch if necessary, satisfies all the rules in the National Electrical Code for the type and location of this switch.
Terminating grounded circuit conductors and equipment conductors
Q: How many equipment grounding conductors can be connected in a single hole in the neutral bus of a service-entrance panelboard? How many grounded circuit conductors are permitted to be connected to one terminal in the same panelboard?
A: It is necessary to review the wiring diagram and read all of the information that appears on the interior of the door of the panelboard before this question can be fully answered.
Some panelboard manufacturers allow two equipment grounding conductors in a single terminal of the neutral bus. The wiring diagram will show which terminals are acceptable for two equipment grounding conductors in a single hole in the bus.
Neutrals or grounded circuit conductors must be connected to individual terminals. Multiple grounded circuit conductors in a single terminal on the neutral bus are prohibited by 408.21, which says: “Grounded Conductor Terminations. Each grounded conductor shall terminate within the panelboard, in an individual terminal that is not also used for another conductor.” The exception allows two or more grounded circuit conductors in parallel to be connected to a single terminal where the terminal is identified for the connection of more than one conductor.
Where there are not enough terminals to accommodate all of the grounded circuit conductors and equipment grounding conductors, a grounding bus kit may be installed to provide additional terminals.
GFCI receptacles in kitchens
Q: Does 210.8(B)(3) require GFCI protected receptacles in the following locations: employee break rooms, employee lounges, meat and seafood markets, food service areas of fast food restaurants and food concession stands in sports arenas? Does the GFCI requirement apply to receptacles in dedicated appliance spaces and non-countertop receptacles? What about receptacles for refrigerators and those that are not readily accessible?
A:Meat and seafood markets are not kitchens unless food is prepared and cooked at these locations. Employee break rooms and employee lounges could be considered as kitchens if there is a sink, countertop and permanent provision for preparing hot meals.
There were a number of proposals to clarify the term “kitchen” submitted to Code Making Panel No. 2 for the 2005 edition of the NEC. In the first round of voting, all members voted for this wording: “Commercial and Institutional Kitchens. For the purpose of this section a kitchen is defined as an area with a sink and permanent facilities for food preparation and cooking.”
The Code Making Panel also stated that the requirement for GFCI protection of 15 and 20A, 125V receptacles applies to all receptacles in the kitchen area regardless of whether the receptacles are located in dedicated spaces, behind refrigerators or not readily accessible.
Where there is concern about GFCIs tripping various kitchen appliances, they should be hard-wired to eliminate this potential problem.
Grounded circuit conductor size for a 3-phase, four-wire delta service
Q: I have a job to install a 400A, 3-phase 120/240V Delta Service. The 3-phase motor load consists of three 10 hp motors each with a full-load current of 28A. These motors are the only 3-phase loads. Is it permissible to use different sizes of conductors for the grounded circuit conductor and the B phase circuit conductor?
A: Service-entrance conductors are permitted to be sized according to their connected loads. Let’s assume that the A and C phase conductors are each 500 kcmil copper conductors with Type THWN insulation. These conductors have an ampacity of 380A. The phase conductor with the higher voltage to ground supplies only 3-phase loads; therefore, a 1/0 copper conductor with Type THWN insulation is acceptable.
The grounded circuit conductor must have a minimum size of 1/0 AWG copper with or without THWN insulation or a maximum size of 300 kcmil copper with or without THWN insulation.
I have not assigned a definite size to the grounded circuit conductor because the maximum unbalanced single-phase load on the grounded circuit conductor is unknown. However, the grounded circuit conductor wire size cannot be smaller than the grounding electrode conductor, which is 1/0 AWG as shown in Table 250.66.
The fused service switch must be provided with a fuse reducer to provide proper overcurrent protection for each service-entrance conductor. The fuses should be dual-element time-delay type. Two 400A and one 125A fuse should do the job.
Nonmetallic device boxes in fire-rated construction
Q: Are nonmetallic device boxes permitted in fire-rated walls and ceilings?
A: Yes they are, provided that they are classified for fire resistance. Nonmetallic device boxes are classified for installation in floors, walls or ceilings. Volume 1 of the 2003 edition of the Fire Resistance Directory published by Underwriters Laboratories Inc. provides detailed information on the installation of various nonmetallic boxes. Here is some of the detailed information included with the fire resistance classification for nonmetallic switch and outlet boxes used in fire resistive walls constructed of wood or nonbearing steel studs and gypsum wall board with two hours or less classifications periods:
• Clearance between boxes and cutouts in walls shall not exceed 1/8 inch;
• The areas of openings for boxes shall not aggregate more than 100 square inches per 100 square feet of wall or partition area with no opening exceeding 22 square inches; and
• Outlet boxes on opposite sides of the wall or partition shall be separated by a horizontal distance of not less than 24 inches.
This is an example of the requirements for the manufacturer of 16 types of nonmetallic switch, device and outlet boxes. The spacing, dimension and location restrictions are not the same for all products. When you know what you need as for as the restrictions are concerned, pick out a box that satisfies your requirements. EC
FLACH, a regular contributing Code editor, is a former chief electrical inspector for New Orleans. He can be reached at 504.734.1720.