Deep Dive LED Drivers: A Contractor’s Field Guide for Long Island Jobs

Updated: August 28, 2025

~11 min read • ~2,250 words • Flesch ~60

TL;DR

Pick CC vs CV based on the LED load, leave voltage and wattage headroom for cold starts and life, match the control protocol on day one, and respect Article 725 separation. Keep drivers cool, label programmed settings, and plan for inrush. When in doubt, call the AHJ before you pull cable. Stock a universal-input CC, a few CV bricks, an SPD, and a 0–10 V tester so you can close tickets on the first visit. Need parts today? Shop LED drivers or swing by your Revco branch.

Why it matters

LEDs fail early a lot less than drivers do. Most callbacks we hear about trace back to mismatched output current, poor thermal placement, noisy dimming, or ignoring surge. Those misses waste time, chew margins, and annoy clients. The fix is simple: choose the right driver, size it correctly, wire it cleanly, and document settings so the next tech isn’t guessing. If you need gear today, you can browse LED drivers in stock at Revco before you roll.

Local note for Long Island crews: many occupancies run 120 or 277 volts, but you’ll also see 347 or 480 in industrial sites. Ambient temps in plenum spaces and coastal surge conditions matter. Always verify with the Authority Having Jurisdiction and any local amendments in Nassau or Suffolk County before you finalize a spec.

Fundamentals

What an LED driver does. It converts line AC to low-voltage DC and regulates current so diodes don’t drift into thermal runaway. The driver often also handles dimming input and protections such as over-temperature, short-circuit, and inrush limiting.

• Constant-current (CC): The driver sets a fixed output current, for example 350 mA, 700 mA, or 1050 mA. The voltage floats within a rated window to satisfy the LED load.
• Constant-voltage (CV): The driver fixes output voltage, commonly 12 or 24 V. Current varies with load. Use this for tape light, channel letters, or modular loads that change after install. See Diode LED tape light solutions for typical CV applications.
• Programmable drivers: Field-adjustable via NFC or a lead set. One SKU can cover multiple currents and dim floors. Record the settings on the fixture or in the panel directory.
• Multi-output drivers: Several isolated channels in one can. Useful for tunable white or RGBW where each channel needs separate control.
• Controls-ready drivers: 0–10 V, DALI-2, phase-cut, or wireless radios like BLE mesh and Zigbee. Match protocol early in design so fixtures, sensors, and relays play nicely.

Driver vs power supply. All drivers are power supplies, but not all power supplies regulate current. If the LED load expects a constant-current source and you feed it a fixed-voltage brick, you risk overcurrent and early failure.

Ripple and flicker. The rectifier and storage stage matter. High ripple can show up as visible flicker or stroboscopic effect. Premium drivers publish low ripple percentages and total harmonic distortion figures. Pick low-ripple drivers for classrooms, retail, and any area with moving machinery.

Code and compliance (NEC 2023 references)

Follow the listing and the label. NEC 110.3(B) requires installation per manufacturer instructions. That covers things like mounting orientation, enclosure fill, torque values, and required spacings.

Class 2 wiring and separation. If the driver outputs a Class 2 circuit, apply Article 725. Keep Class 2 conductors separated from power-limited and nonpower-limited circuits as required by 725.136, and use wiring methods permitted by 725.130. Where Class 2 leaves the luminaire to remote LEDs or controls, plan routing and identification so no one confuses it with line-voltage runs.

Low-voltage lighting systems. Article 411 governs certain lighting systems operating at not more than 30 volts. Where your driver and luminaire fall under 411 scope, ensure the power source and luminaires are listed for the purpose and used within their ratings per 411.3 and 411.4.

Disconnects and retrofit work. Where luminaires use replaceable double-ended LED lamps or have retrofit kits, review 410.71 for disconnecting means and safe servicing. For emergency lighting circuits using power-limited outputs, maintain the separation and survivability required in the applicable article, such as 700.11(D) for emergency feeders and associated Class 2 control circuits routed with them.

New cable families. Be aware that Article 722 addresses certain cables used with Class 2, Class 3, and Class 4 circuits. When you’re in plenum spaces, pick the proper rating and keep supports, derating, and identification straight.

Local adoption disclaimer: Always verify which NEC cycle is enforced by your AHJ and whether there are county or village amendments on Long Island. When in doubt, submit a quick RFI before rough-in.

Selection steps

1. Confirm LED topology. COB, mid-power board, or tape. Pull the module datasheet for forward voltage (Vf) at operating temperature and the rated drive current (If).
2. Choose CC or CV. Use CC for board, COB, and most integral fixtures. Use CV for tape and modular signage. If the load could change later, CV keeps life simple.
3. Match the output range. For CC, pick a voltage window that covers the LED’s Vf across temperature. Cold starts raise Vf, so leave headroom. For CV, ensure the driver’s wattage and current limit can cover the worst-case load without brownout.
4. Size the wattage. Aim to run CC drivers at roughly 80 to 90 percent of rated watts under normal ambient. For CV systems with diversified loads, 60 to 75 percent loading improves efficiency and thermal life. Oversizing a little reduces case temperature and prolongs electrolytic capacitor life.
5. Pick the control protocol. If the job uses networked controls, lock the protocol first. 0–10 V is common and simple. Line-voltage phase-dimming drivers exist, but check compatibility with the specific dimmer family. If you need relays and sinks, review 0–10 V control modules that are listed with your fixtures.
6. Check environmental ratings. Look at minimum and maximum ambient temperature (Ta), case temperature limits at the Tc point, and ingress protection. In coastal or washdown areas, favor higher IP ratings and stainless mounting hardware. In plenums, confirm plenum-rated cable and spacing requirements.
7. Account for inrush and breaker sizing. Review the driver’s inrush current, duration, and recommended maximum fixtures per breaker. Large banks on 277 V can nuisance-trip breakers at energization. Staggered start, NTC limiting, or different breaker curves may be justified.
8. Document the settings. For programmable drivers, label output current, dim floor, trim levels, and any timing functions. Put the label inside the luminaire door or on the panel schedule so the service tech can match replacements quickly.

Pro tip: When you’re pairing CV drivers with tape light, keep total run length within the manufacturer’s voltage-drop guidance and feed long runs from both ends. If you’re building a kit cart for service calls, carry a universal-input CC driver and a few CV bricks plus a basic dimmer sink to test 0–10 V behavior in the field.

Sizing and configuration examples (with shown math)

Example 1: Constant-current downlight array

Given: Four LED boards in parallel. Each board If = 280 mA at 25 °C, Vf = 33 V at operating temp. Target 10 percent headroom for cold starts. Driver efficiency 90 percent typical.

• Total current Itot = 4 × 0.280 A = 1.12 A.
• Allow Vf headroom: 33 V × 1.10 = 36.3 V worst case. Pick a driver with a voltage window that covers 30–40 V.
• Electrical output power Pout = V × I ≈ 33 V × 1.12 A = 36.96 W at normal temp.
• Add margin for programming and thermal: choose a 60 W CC driver.
• Approximate input power Pin = Pout / η ≈ 36.96 / 0.90 = 41.07 W.

Selection: CC driver set to 1.20 A max, trim to 1.12 A; output window 30–40 V; nameplate 60 W. This runs at about 36.96/60 = 62 percent of rated output, which helps keep the case cooler and extends capacitor life.

Example 2: CV tape light run with voltage drop

Given: 24 V tape, 4.0 W/ft, 20 ft run from a single feed, 0.5 A per 3 ft segment per manufacturer table, using 16 AWG pair with 4 mΩ/ft loop resistance (round trip).

• Load current Itot ≈ 4.0 W/ft × 20 ft / 24 V = 3.33 A.
• Conductor resistance Rloop = 0.004 Ω/ft × 20 ft = 0.08 Ω.
• Voltage drop ΔV = I × R = 3.33 A × 0.08 Ω = 0.266 V.
• Percent drop = 0.266 / 24 × 100 ≈ 1.1 percent which is acceptable (keep under 3 percent for even brightness).

Selection: Use a 24 V CV driver rated 100 W minimum to keep loading near 60–70 percent for thermal comfort. For longer runs, feed from both ends or center-feed to keep drop low. For parts, see low-voltage cable.

Example 3: Inrush and maximum fixtures per breaker

Given: Driver datasheet lists inrush 40 A peak, 200 μs, at 277 V. 20 fixtures on a 20 A breaker. Thermal-magnetic breaker instantaneous trip around 7× In = 140 A typical.

• Worst-case simultaneous inrush ≈ 20 × 40 A = 800 A for 200 μs. Breakers evaluate energy at a few ms, so 200 μs spikes might be tolerated, but upstream gear and nuisance trips are still possible when waveforms stack.
• Mitigate by staggering start or dividing into two circuits. With 10 fixtures per circuit, peak ≈ 400 A and the probability of cumulative overlap drops.

Selection: Use a time-delay breaker where allowed, add NTC limiting, or specify drivers with lower inrush. Verify the maximum fixtures per breaker table in the driver datasheet before rough-in.

Installation and wiring notes

• Torque is life. Tighten terminal blocks to the manufacturer’s spec to avoid hot joints. Record torque values if the instructions require it. Keep line and Class 2 conductors neatly separated per Article 725.
• Conductor ID and routing. Use distinct jacket colors or labels for 0–10 V control leads. Keep control wiring out of the same raceway as line where separation rules apply. For new builds, grab listed 0–10 V control cable and keep bend radii generous to avoid noise pickup.
• Thermal placement. Do not bury drivers in insulation or stack them tight in a hot plenum. Respect Ta and Tc limits. If the plenum runs hot, remote-mount drivers in a cooler space and use proper cable types.
• Bonding and grounding. Bond metal driver cases when marked as Class I. A floating case can invite EMI and intermittent faults.
• Wet locations. Choose IP65 or better housings and sealed connectors for washdown or coastal jobs. Use liquid-tight fittings and maintain drip loops.
• Controls first. Decide on 0–10 V, phase-cut, DALI-2, or wireless during design. Use listed control hardware matched to your fixtures and follow the vendor’s wiring topology.
• Surge protection. Coastal Long Island sees rough power. Add a luminaire-level SPD or panel SPD on outdoor poles and long runs. Stock options are under surge protection devices.

Testing, commissioning, and documentation

• Functional tests. Verify correct polarity, no-load behavior, and dimming response from 100 to 1 percent. Confirm that minimum dim does not flicker or drop out.
• Ripple/flicker check. For sensitive spaces, use a flicker meter or a high-speed phone app to confirm low ripple. Favor published low-ripple drivers for classrooms, labs, and production floors.
• Programming records. For programmable drivers, note output current, dim floor, and any time-out or trim. Stick a label inside the luminaire door or at the panel directory.
• Controls integration. Commission sensors and timeouts. For 0–10 V, check that control wiring is not referenced to ground incorrectly. For networked controls, save the project file in the client folder.
• Rebate paperwork. Many utility programs ask for driver specs, controllability, and efficacy. Gather cut sheets, a power measurement snapshot at full and at a dimmed level, and your programming notes.

Troubleshooting

Common mistakes to avoid

• Mixing CC and CV loads on a single output.
• Ignoring cold-start Vf and choosing too narrow a voltage window.
• Forgetting inrush. Twenty small fixtures can behave like a welder at turn-on.
• Running CV drivers near 100 percent on long tape runs. Load at 60–75 percent instead.
• Skipping labels for programmed current and dim-floor settings.
• Combining control protocols without a gateway or tested compatibility list.

Parts to stock + Shop at Revco

• LED drivers for CC and CV jobs.
• Dimmers and interfaces including 0–10 V and line-voltage types.
• Surge protective devices for panels and branch protection.

When to call the AHJ or an engineer

• Mixed systems with emergency egress, shunt relays, or integral batteries.
• Large driver banks on 277/480 V where inrush and harmonics affect upstream gear.
• Hazardous locations, wet-loc food service, or corrosive atmospheres.
• Any installation that blends Class 2 with higher-class circuits in shared spaces or raceways.

Safety disclaimer

This guide summarizes good practice and selected NEC 2023 references. Always install per the driver’s listing and instructions and verify local adoption with the Authority Having Jurisdiction for Long Island, NY. Where this guidance and the listing differ, follow the listing and the AHJ’s direction.

FAQ

• How do I tell CC vs CV quickly? CC lists output current as a range in amps or milliamps with a voltage window. CV lists a fixed output voltage like 12 or 24 V and a maximum current or wattage.
• Do I need a separate SPD? Yes for outdoor poles, long feeders, or sites with frequent storms. Add a panel SPD and a luminaire-level SPD for best resilience.
• What minimum dim level is safe? Many drivers hold steady to 1 percent on 0–10 V, but check the datasheet and test on site. Too low can cause dropout or shimmer.
• Why did the driver fail early? Heat shortens capacitor life. If the driver ran hot or at full rating, life drops. Upsize slightly and improve placement.
• Can I reuse existing control wiring? Often, yes for 0–10 V if the cable type and separation meet Article 725. For networked controls, follow the vendor’s topology and cable requirements.
• Is phase-cut dimming OK with LEDs? Sometimes. Use a driver listed for the specific dimmer family. If performance is critical, 0–10 V or DALI-2 is more predictable.

About Revco Lighting & Electrical Supply

Since 1978, Revco Lighting & Electrical Supply has been helping professionals bring their projects to light—literally. As a go-to source for lighting and electrical products across Long Island, NY and nearby areas, we specialize in supporting contractors, builders, and industry experts with practical solutions and dependable service. Whether it’s a complex commercial build or a simple residential upgrade, we’re here to make sure you have what you need, when you need it.

Author: Revco Editorial Team — Electrical Content Editor
Technical review: Pending — add approved name/credential
Contact: (631) 283-3600

Sources

1. NFPA, NFPA 70: National Electrical Code (NEC), 2023 Edition. Retrieved Aug-2025: nfpa.org
2. UL, UL 8750: Light Emitting Diode (LED) Equipment for Use in Lighting Products. Retrieved Aug-2025: shopulstandards.com
3. U.S. DOE SSL Program, Flicker in Solid-State Lighting: A Review of the TLM Stimulus and Human Response. Retrieved Aug-2025: energy.gov
4. DesignLights Consortium, SSL Technical Requirements v5.1. Retrieved Aug-2025: designlights.org