12.6 Electric Signs & Outline Lighting (Article 600) and Lighting Systems 30 Volts or Less (Article 411)
Key Takeaways
- NEC 600.5(A) requires at least one sign or outline lighting outlet at each entrance to each tenant space in a commercial building or occupancy accessible to pedestrians, supplied by a branch circuit rated at least 20 amperes that supplies no other load.
- NEC 220.14(F) requires a minimum of 1200 volt-amperes to be included in the calculated load for each required sign or outline lighting branch circuit.
- NEC 600.6 requires a disconnecting means that opens all ungrounded conductors of the sign or outline lighting system, located within sight of the sign or the controller, or capable of being locked in the open position.
- NEC 600.32 limits neon secondary circuit conductors to 1000 volts and requires listed GTO cable installed in a listed raceway or the sign body, with the secondary circuit kept as short as practicable.
- Article 411 lighting systems operating at 30 volts or less must be supplied from a branch circuit rated no more than 20 amperes, with the power supply output limited to 30 volts (42.4 volts peak) and 25 amperes maximum.
12.6 Electric Signs & Outline Lighting (Article 600) and Lighting Systems 30 Volts or Less (Article 411)
Lighting and Signs carries 10 scored items on the PSI outline — the same weight as Grounding and Bonding and more than Conductors and Cables. Section 12.2 covered luminaire installation under Article 410. Two of the eight listed sub-topics, lighting systems that operate at less than 30 volts and neon lighting and electric signs, live in entirely different articles that a general journeyman course usually skips.
1. Article 600 — Electric Signs and Outline Lighting
The required sign outlet (600.5)
NEC 600.5(A) requires that each commercial building and each commercial occupancy accessible to pedestrians be provided with at least one outlet in an accessible location at each entrance to each tenant space for sign or outline lighting use.
| Requirement | Value |
|---|---|
| Minimum branch-circuit rating | 20 amperes |
| Other loads permitted on that circuit | None — except loads directly related to control of the sign, such as electronic or electromechanical controllers |
| Minimum calculated load per required branch circuit | 1200 volt-amperes (NEC 220.14(F)) |
| Where the outlet is not required | Service hallways or corridors, which are not considered accessible to pedestrians |
Load-calculation consequence. A strip center with eight tenant spaces has eight required sign outlets. That is 8 × 1200 VA = 9,600 VA that must appear in the service calculation whether or not a single tenant has hung a sign yet. Candidates who calculate a shell-building service and forget the sign load undersize the service.
Disconnecting means (600.6)
Each sign and outline lighting system, and each feeder circuit or branch circuit supplying a sign, must have a disconnecting means that opens all ungrounded conductors and is either within sight of the sign or outline lighting system it controls, or capable of being locked in the open position with the locking means remaining in place with or without the lock installed. Where the sign is operated by an electronic or electromechanical controller located externally, the disconnect is permitted to be within sight of the controller — with a field-applied permanent label on the sign identifying the disconnect location.
Grounding, bonding, and listing
- Signs and outline lighting systems must be listed and installed per the installation instructions unless they are field-installed skeleton tubing or otherwise specifically addressed.
- 600.7 requires the metal parts of the sign to be grounded and bonded. The bonding conductor for sign sections and metal parts is a specified minimum copper size, and the bonding path must be continuous through metal raceways and across sign sections. Where a remote metal enclosure or a section of a sign is separated, an equipment bonding jumper is required.
- 600.21 requires that transformers, power supplies, ballasts, and drivers be accessible — an attic or suspended-ceiling location must have an access opening and adequate working space, and the equipment may not be permanently sealed behind finish.
- 600.24 covers Class 2 power sources used in signs, permitting Class 2 wiring methods for the low-energy portions of the system.
Portable and mobile signs (600.10)
A portable or mobile sign — the wheeled arrow board in a parking lot — must be listed, must be supplied through a flexible cord of limited length, and must be provided with ground-fault circuit-interrupter protection, either integral to the sign or in the attachment plug.
Neon: field-installed skeleton tubing (Part II)
| Rule | Requirement |
|---|---|
| Secondary voltage limit (600.32) | 1000 volts maximum for neon secondary circuit conductors |
| Secondary conductor type | Listed GTO cable, rated for the voltage, installed in a listed raceway or in the sign body/metal enclosure |
| Length | Secondary conductors kept as short as practicable; the longer the high-voltage run, the greater the capacitive loss and the fire risk |
| Spacing | Secondary conductors must be spaced from each other and from grounded metal per the article; the raceway must be sized so the high-voltage insulation is not compressed |
| Transformer/power supply | Must be listed, marked with the secondary voltage and current, and provided with secondary-circuit ground-fault protection |
| Electrode connections | Made inside a listed receptacle or enclosure; bare electrode terminals may not be accessible to unqualified persons |
A journeyman is not usually the person bending the tubing, but is the person who lands the primary circuit, mounts and grounds the transformer enclosure, and gets the disconnect right.
2. Article 411 — Lighting Systems Operating at 30 Volts or Less
Article 411 governs the low-voltage lighting systems used for landscape lighting, display lighting, cove lighting, and cable/rail systems: a listed assembly of an isolating power supply, the low-voltage luminaires, and the connecting wiring.
| Rule | Requirement |
|---|---|
| Supply branch circuit | Rated not more than 20 amperes |
| Secondary output | 30 volts maximum (42.4 volts peak), 25 amperes maximum under all load conditions |
| Listing | The lighting system must be listed as a complete system, or assembled from listed components identified for the use |
| Bare conductors | Permitted only as part of a listed system, installed so that accidental contact and short circuits between conductors are prevented |
| Concealed or extended wiring | Where the secondary wiring is concealed or extended through a building wall, it must use a Chapter 3 wiring method |
| Pools, spas, and fountains | Article 411 systems may not be installed within 10 feet (3.0 m) of pools, spas, fountains, and similar locations except as permitted by Article 680 |
[!WARNING] "Low voltage" is not "low energy." A 300-watt landscape transformer at 12 volts sources 25 amperes into a bare conductor pair. That is more than enough to melt a wedding ring, ignite dry mulch at a damaged splice, or set a landscape wire on fire under a mower cut. The 25-ampere output cap and the listing requirement in Article 411 exist precisely because the shock hazard is low and the thermal hazard is not.
3. Fluorescent, Recessed, and Closet Rules from Article 410
The remaining Lighting and Signs sub-topics — fixture construction requirements, fluorescent fixtures, and recessed fixtures — are Article 410 rules that produce exam items every cycle:
- Recessed luminaire clearances (410.116). A non-IC-rated recessed luminaire must have at least ½ inch of clearance from combustible materials (except at the points of support), and thermal insulation must be kept at least 3 inches from the enclosure and wiring compartment and may not be installed above the luminaire so as to entrap heat. A luminaire identified for insulation contact (Type IC) may be in direct contact with insulation and covered by it.
- Fluorescent ballast disconnect (410.130(G)). Fluorescent luminaires that use double-ended lamps and contain ballasts must have a disconnecting means in indoor locations, external to or accessible within the luminaire, so a maintenance worker can de-energize the ballast without pulling a branch-circuit breaker in another room. The disconnect must simultaneously break all supply conductors, including the grounded conductor.
- Bathtub and shower zone (410.10(D)). No cord-connected luminaire, chain-, cable-, or cord-suspended luminaire, lighting track, pendant, or ceiling-suspended paddle fan may be located within a zone measured 3 feet horizontally and 8 feet vertically from the top of the bathtub rim or shower stall threshold. Luminaires in that zone must be listed for damp locations, or listed for wet locations where subject to shower spray.
- Clothes closet clearances (410.16). Minimum clearance from the nearest point of a storage space: 12 inches for a surface-mounted incandescent or LED luminaire with a completely enclosed light source; 6 inches for a surface-mounted fluorescent luminaire; 6 inches for a recessed incandescent or LED luminaire with a completely enclosed light source; 6 inches for a recessed fluorescent luminaire. Surface-mounted fluorescent or LED luminaires are permitted within the storage space where identified for that use. Open-lamp incandescent luminaires and pendants are not permitted in clothes closets at all.
A new strip center has six tenant spaces, each with a pedestrian entrance from the parking lot. What does NEC 600.5(A) require, and what must the service calculation include under 220.14(F)?
A landscape lighting system operates at 12 volts from a listed transformer. Which installation complies with Article 411?
A neon sign is installed on a commercial storefront with the transformer mounted in a metal raceway enclosure behind the sign face. Which statement reflects the Article 600 rules for the neon secondary circuit?
A non-IC-rated recessed luminaire is installed in an insulated ceiling. What does NEC 410.116 require?