Horticultural lighting equipment

We are a startup indoor marijuana cultivation company and have questions about LED fixtures. We have been told a field evaluation is necessary for LED fixtures if we use them. We find this very confusing. We are researching best fixtures for our application, considering safety, performance and cost. What is involved in a field evaluation?

The general requirement in Part I of Article 410 in Section 410.2 requires all luminaires, lampholders, lighting systems and retrofit kits to be listed. Where electrical equipment and devices are required to be listed, Section 110.3(C) applies. This requirement clarifies that the individual product is tested and evaluated by recognized, qualified electrical testing laboratories in accordance with applicable product standards. You can likely acquire listed LED luminaires for this application. The specifications (cut sheets) will provide this information.

Some manufacturers will state compliance with a given product standard, but it may not be listed. An informational note following Section 110.3(C) informs the code user that OSHA provides a formal list of qualified electrical testing laboratories that apply a listing mark to signify that the product complies with the requirements of one or more appropriate product safety test standards.

Additionally, Article 410, Part XV, contains requirements for luminaires in this application, with special provisions for horticultural lighting equipment. This part mandates compliance with general rules in the article and modifications and supplemental requirements. For example, Section 410.176(A) prohibits lighting equipment identified for horticultural use from being used for general illumination unless the use is indicated in the manufacturer’s instructions. If the LED chosen is identified for horticultural use and uses flexible cords with one or more separable connectors or attachment plugs, it must be installed in accordance with Section 410.184.

This mandates ground-fault circuit interrupter (GFCI) protection for branch circuits 150V or less to ground, single- or three-phase and branch circuits rated above 150V to ground, single- or three-phase, must be protected with a listed SPGFCI with a ground-fault trip current not exceeding 20 mA. If the luminaires installed are not listed, a field evaluation is required. A field-­applied label, symbol or other identifying mark is applied to indicate the luminaires were evaluated and found to comply with requirements as described in an accompanying field evaluation report.

Temporary splices

Is it permitted to splice Type SE and SER cable without a junction box in construction for temporary splices? What about Type NM and MC?

The general rule in Section 590.6(F) requires a box, conduit body or other enclosure with a cover installed for all splices. Exception No. 1 addresses construction sites permitting open splices where the conductors spliced are all from nonmetallic multiconductor cord or cable assemblies, provided that the equipment grounding continuity is maintained with or without the box. This includes Type SE and NM cable assemblies. This exception also permits metal-sheathed cable assemblies (including Type MC and AC) to be terminated in listed fittings (such as duplex or double connectors) that mechanically secure the cable sheath to maintain effective electrical continuity.

Size of service conductors

For a 400A service to a retail store (a deli) we installed 600-kcmil aluminum conductors from the metering equipment to the service disconnect, a 400A circuit breaker. It was failed during a service inspection, and we had to install parallel 4/0 aluminum so he would approve it. Was that right? We install 400A services with 600-kcmil aluminum all the time.

The inspector was correct. It is common to see a 400A service to a dwelling unit with 600-kcmil aluminum conductors due to the permissive requirements in Section 310.12(A). This rule permits an ampacity reduction to 83% of the service rating where the service conductors supply the entire load associated with an individual dwelling unit. Additionally, where no adjustment or correction factors are required, Table 310.12(A) is permitted to be applied for conductors or cables rated 75°C (167°F) or greater. This table permits 600-kcmil aluminum for a dwelling unit service at 400A.

In a commercial installation, Section 310.12 does not apply. A 75°C, 600-kcmil aluminum is rated at 340A. Applying the permissive requirements of Section 240.4(B), it is permitted to round up from 340A to the next higher standard rating in Section 240.6, which is 350A and is undersized for a 400A service. Paralleling two 75°C, 4/0 aluminum conductors, each rated at 180A, results in 360A, which can be rounded up to 400A provided the requirements of Article 220 are met for the connected load.

GFCI in hardwired equipment

Can you provide some insight on a code disagreement? The issue is GFCI protection in a commercial kitchen. Is GFCI protection required for hardwired cooking equipment?

No, GFCI protection is not required for hardwired equipment. The requirement in 210.8(B) for GFCI protection in other than dwelling units applies only to 125V through 250V receptacles supplied by single-phase branch circuits rated 150V or less to ground, 50A or less, and all receptacles supplied by three-phase branch circuits rated 150V or less to ground, 100A or less. Note that the GFCI requirement addresses receptacles and not outlets. If this requirement’s intent was to provide GFCI protection for hardwired equipment and receptacles, it would be modified by deleting “receptacles” and adding “outlets.”

Permanent switching means

A plans examiner is requiring us to install a means to connect a temporary generator to allow for maintenance of the emergency system generator in a commercial occupancy. Is that required?

See the general rule in Section 700.4(F), which requires emergency systems relying on a single alternate source of power (typically a single standby generator), which will be disabled for servicing, to have a permanent switching means to connect a portable or temporary alternate source of power that shall be available for the duration of the servicing. The exception following this requirement may apply in your installation, exempting the requirement for a permanent switching means to connect a portable or temporary alternate source of power where any of the following conditions exist: (1) all processes that rely on the emergency system source are capable of being disabled during maintenance or repair of the emergency source of power, (2) the building or structure is unoccupied and fire protection systems are fully functional and do not require an alternate power source, (3) other temporary means can be substituted for the emergency system or (4) a permanent alternate emergency source, such as, but not limited to, a second on-site standby generator or separate electric utility service connection capable of supporting the emergency system, exists.

Direct burial suitable for concrete encasement?

Where concrete will be poured over ground rods used to supplement an underground water pipe, do we need a special type of connector to the rod?

See Section 250.70 for permitted methods of bonding to electrodes. The general rule is that ground clamps be listed for grounding electrode and grounding electrode conductor materials, and only one conductor can be connected to the grounding electrode by a single clamp or fitting unless the clamp or fitting is listed for multiple conductors. Where encased in concrete, Section 250.70(A)(2) requires ground clamps used on pipes, rods or other buried electrodes be listed for direct soil burial or concrete encasement. An associated informational note explains that listed ground clamps identified for direct burial are also suitable for concrete encasement.

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