Class 2 Power Supply: NEC & UL 1310 Explained

Q: What is a Class 2 power supply?

A power supply whose output is power-limited under the NEC (listed to UL 1310 in the U.S.), so the circuit it feeds is low fire and shock risk and can use simplified wiring. The headline limit is roughly 100 VA. Common on LED drivers, CCTV, and access-control power.

Q: What is UL 1310?

UL 1310, Class 2 Power Units, is the U.S. safety standard a supply is listed to in order to be marked Class 2. Ask for the UL 1310 test report keyed to your exact voltage and current variant, and confirm the Class 2 marking appears on your label.

Last Updated: July 6, 2026 · Reviewed by the Sunshine Electronics engineering team

This is a compliance deep-dive on Class 2 power supplies. For the full product reference, see our 12V Power Supply Buyer’s Guide.

Quick answer

For an OEM designing a low-voltage product, a Class 2 power supply is an NEC/UL 1310 power-limited source — output held under roughly 100 VA so the circuit is low fire and shock risk and can use simplified wiring. It is unrelated to Class II (the IEC double-insulation class). Spec Class 2 when your rail must qualify as low-energy per NEC Article 725; skip it when your load exceeds the cap.

If you are designing a product with a low-voltage rail — an LED fixture, a camera, an access-control panel, a sensor — the phrase Class 2 power supply decides your wiring method, your install cost, and which safety listing your bill of materials has to carry. It is also one of the most misunderstood terms in the spec, because it is routinely confused with the similar-looking but entirely different Class II. This guide is the compliance view an OEM buyer or design engineer actually needs.

It is written by the engineering team at Sunshine Electronics — 22+ years building external and embedded power supplies across our dual-factory operations in China and Vietnam for North American lighting, networking, and security OEMs, under UL 62368-1, UL 1310, FCC Part 15-B, CE, and DoE Level VI. Class 2 listing is a routine part of those programs.

Contents

01What Is a Class 2 Power Supply?
02Class 2 vs Class II: The One-Letter Difference
03NEC Class 2 Power Limits: The Actual Numbers
04UL 1310 Listing: What It Covers & How to Verify
05When (and When Not) to Spec Class 2 for Your Product
06Frequently Asked Questions

What Is a Class 2 Power Supply?

A Class 2 power supply is defined by the U.S. National Electrical Code, not by the product’s shape or voltage. It is a supply whose output is power-limited — capped low enough in voltage, current, and volt-amps that the circuit it feeds is considered a low risk of fire ignition and electric shock. Because the energy is limited at the source, downstream wiring can use lighter methods than a full line-voltage circuit, which is the whole commercial point of speccing one.

The reason the limit exists is safety energy, not device protection. Holding the deliverable power under the threshold is what keeps a fault from becoming an ignition or shock hazard, the same principle behind the workplace wiring rules in OSHA 1910.303. In the U.S. a Class 2 supply is listed to the UL 1310 standard; you will see it on nameplates for LED drivers, CCTV supplies, and access-control and signaling power — the low-voltage building blocks a Class 2 rail is built for.

Class 2 vs Class II: The One-Letter Difference

The single most expensive mistake in this area is treating Class 2 and Class II as the same thing. They are unrelated, and a spec that names the wrong one can send the wrong product into a design. Class 2 (Arabic numeral) is the NEC/UL 1310 power-limited output concept above — it is about how much energy the supply can deliver.

Class II (Roman numeral) is an entirely different idea: it is an IEC equipment-construction class meaning the product protects the user through double or reinforced insulation rather than a protective earth ground, and it is governed by product-safety standards such as UL/IEC 62368-1. A supply can be Class II construction (double-insulated, two-prong, no earth pin) and also be Class 2 output (power-limited) — or either one without the other. When you write the RFQ, state which you mean; the two words are one letter apart and carry completely different requirements.

NEC Class 2 Power Limits: The Actual Numbers

The NEC sets the actual thresholds, and they are the numbers an engineer needs. For a Class 2 circuit the headline figure is 100 VA: for the common case of a supply above 20V and up to 30V, output is limited to roughly 100 VA, which is why so many Class 2 units are 24V at a few amps. Below about 20V the current limit dominates instead, and the deliverable power falls accordingly — a 12V Class 2 rail is limited more by current than by the VA cap.

Two things follow from that cap. First, Class 2 is not a power level you can simply scale — cross the VA limit and the supply is no longer Class 2, full stop, regardless of how it is built. Second, the limit is on the output; the supply still has to meet the ordinary mains-side rules, including FCC Part 15 Subpart B emissions for any switching design. Class 2 is also distinct from Class 3, which permits higher voltages under a different limited-energy regime; most low-voltage OEM products land in Class 2.

UL 1310 Listing: What It Covers & How to Verify

In the United States, the listing that makes a supply Class 2 is UL 1310, “Class 2 Power Units.” A unit built and tested to UL 1310 carries the mark and a nameplate that explicitly states “Class 2” along with the output rating — that wording on the label is the fastest field check that a part actually qualifies, rather than merely being a low-voltage adapter.

For an OEM program, the certificate is the entry point, not the proof. Ask for the UL 1310 test report keyed to the exact output voltage and current variant you are buying, confirm the file number resolves in UL’s database, and check that the “Class 2” marking will appear on your label and model number, not just the supplier’s catalog sheet. A supply that is genuinely Class 2 also simplifies your own product’s certification, because the power-limited output reduces what the end device has to prove.

From our certification team

the check we run before quoting a Class 2 build is that the UL 1310 report matches the exact voltage and current on the customer’s drawing, because the listing is per-variant — a report for a 24V 1A unit does not cover a 24V 2.5A one. Confirming the file number and the on-label wording up front is what keeps a Class 2 claim from failing at the inspector’s desk.

When (and When Not) to Spec Class 2 for Your Product

Spec a Class 2 supply when your product benefits from the low-energy classification: LED lighting and signage, CCTV and access control, signaling, and similar low-voltage loads where a Class 2 rail lets the installer use lighter wiring methods and simplifies the field inspection. For those categories it is often effectively expected, and choosing a Class 2-listed supply up front removes a compliance question from the whole downstream install. Efficiency rules still apply on top: an external Class 2 adapter must also clear U.S. DoE Level VI floors.

Do not force Class 2 where it does not fit. The 100 VA cap is a hard ceiling — a load that needs more power cannot be served by a single Class 2 output, and splitting into multiple Class 2 outputs to stay under the limit adds cost and complexity you should weigh honestly. Match the classification to the application, and confirm the output type and listing against your device at the RFQ stage. For selecting the underlying supply, our DC power supply selection guide and wall-mount adapter range cover the form factors.

From our engineering team

the trade-off we walk customers through is simple — Class 2 buys you cheaper, faster field wiring, but it caps you near 100 VA. If a fixture needs more, we would rather size one correctly-rated non-Class-2 supply than daisy-chain Class 2 outputs to dodge the limit. The application decides; we build to it.

Frequently Asked Questions

What is a Class 2 power supply?

It is a power supply whose output is power-limited under the NEC (listed to UL 1310 in the U.S.), so the circuit it feeds is low fire and shock risk and can use simplified wiring. The headline limit is roughly 100 VA. It is common on LED drivers, CCTV, and access-control power.

Is Class 2 the same as Class II?

No. Class 2 (numeral) is an NEC power-limited output concept. Class II (Roman) is an IEC construction class meaning the product uses double or reinforced insulation instead of a ground. A supply can be one, both, or neither — always state which you mean.

What are the Class 2 power limits?

Roughly 100 VA for supplies above 20V (which is why many Class 2 units are 24V at a few amps); below about 20V the current limit dominates. Cross the limit and the supply is no longer Class 2 regardless of construction. Class 3 covers higher-energy limited circuits.

What is UL 1310?

UL 1310, “Class 2 Power Units,” is the U.S. safety standard a supply is listed to in order to be marked Class 2. Ask for the UL 1310 test report keyed to your exact voltage and current variant, and confirm the “Class 2” marking appears on your label.

Do I need a Class 2 power supply for LED lighting?

For most low-voltage LED and signage work it is effectively expected, because it simplifies wiring and inspection. Confirm the load stays under the ~100 VA Class 2 cap; if it does not, use a correctly rated non-Class-2 supply instead of splitting outputs.

Conclusion

Class 2 is a compliance classification, not a product category: it means the supply’s output is power-limited under the NEC and listed to UL 1310, and it is a different thing entirely from Class II double insulation. For an OEM, getting it right decides the wiring method, the install cost, and how cleanly the end product certifies.

Confirm three things before the PO: that the load stays under the Class 2 cap, that the UL 1310 report matches your exact variant, and that the “Class 2” marking lands on your label. Get those right and the classification stops being a source of confusion and starts being a design advantage.

Ready to Source a Class 2 Power Supply?

Sunshine builds Class 2-listed and standard low-voltage supplies to a controlled spec — UL 1310, UL 62368-1, FCC, CE, and DoE Level VI with matching test reports — at our dual-factory operations in China and Vietnam, so one certified SKU stays shippable from either site. See our certifications and compliance overview for the full listing scope, and our manufacturer vetting checklist for how to qualify a supplier. Our OEM program team returns a quoted spec sheet and certification scope within 3 business days of an RFQ.

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