NEC 230.67: The Surge Protector Your License Now Depends On
This rule is younger than most candidates' careers, which is exactly why it tests well: a 20-year journeyman who learned services before 2020 has never installed one on principle. Every dwelling service gets an SPD, a panel swap triggers it too, and the exam wants the type and the location.
Last reviewed September 2026
What the rule requires
- Scope: services supplying dwelling units.
- Device: an SPD listed as Type 1 or Type 2. The plug-strip Type 3 does not qualify.
- Location: integral to the service equipment or immediately adjacent, or at each next-level distribution panel downstream.
- Replacement: swapping the service equipment brings the requirement with it.
Type 1 versus Type 2, in one breath
The types are defined by where the device is listed to live relative to the service disconnect. Type 1 is listed for the line side, ahead of the main overcurrent device. Type 2 is listed for the load side, which is where the everyday breaker-style and side-mounted SPDs go. For a dwelling service, either satisfies the rule, and the exam answer that names both types together is usually the right one.
Why the code added it
The average dwelling now runs on electronics wall to wall. The furnace board, the range control, the doorbell transformer's smart replacement, and the AFCI and GFCI devices in the panel itself are all vulnerable to transient voltage spikes from utility switching and nearby lightning. One service-level SPD clamps those transients for the whole structure. The code concluded that protecting the safety electronics alone justified the requirement.
Where candidates lose the point
- Treating the SPD as optional on a new dwelling service. It is required equipment.
- Missing the replacement trigger. A panel swap on a 1980s house includes an SPD under the current code.
- Accepting a Type 3 device as the answer. Point-of-use strips do not satisfy 230.67.
- Placing it anywhere convenient. In or adjacent to the service equipment, or at each downstream distribution panel.
- Extending the rule to every occupancy. 230.67 is written for dwelling services.
How it shows up on the exam
Three forms. The direct one: what surge protection does a new dwelling service require, answered with Type 1 or Type 2 in or adjacent to the service equipment. The remodel one: a service equipment replacement, testing whether you know the requirement follows. And the odd-one-out: a list of SPD types where Type 3 is planted as the trap. All three are pure recall, which makes this among the cheapest points on the paper for anyone who has read the rule once.
The newest rules are the easiest points to lose
Requirements added in recent code cycles blindside experienced electricians hardest. The free diagnostic includes them, because the exam does.