The outlet on the side of the island, just under the countertop, is the one every builder used. Under the 2023 code it no longer counts.

Ask which code cycle your jurisdiction is on before designing the electrical

This is the first question and it changes the answer completely, because adoption is local and three different rules are currently in force somewhere. Under the 2017 NEC at least one receptacle was required where the island’s long dimension was 24 inches or more and its short dimension 12 inches or more. Under the 2020 NEC and 2021 IRC receptacles were required with the count based on countertop square footage, peninsulas needed one near the outer end, and receptacles below the countertop were allowed. Under the 2023 NEC and 2024 IRC an island receptacle is not mandatory at all, and if one is installed it cannot be below the counter on the side. Building code guidance states the practical instruction directly: ask your authority having jurisdiction whether they are on 2017, 2020 or 2023. The same island passes in one county and fails in the next.

The side-mounted outlet is the specific thing that stopped being allowed

Worth being precise about, because it is the detail most likely to be built from habit. NAHB describes the change plainly: for many years the NEC permitted receptacles on the vertical sides of islands and peninsulas to satisfy countertop outlet requirements, builders commonly located them just below the countertop edge or within decorative panels on the base, and the 2023 code removes that allowance in jurisdictions that adopted it unamended. So a side-mounted receptacle is not merely discouraged, it no longer counts toward serving the countertop. If a crew is working from memory rather than from the current code, this is the thing they will do.

The reason is burns, and it is worth telling a client

This is a change with a documented motivation rather than a bureaucratic one, and explaining it usually ends the argument about whether it matters. Hubbell states that the revised language was adopted because of the many reports of injuries and burns resulting from countertop cooking appliances tipping and spilling. The mechanism is easy to picture: a receptacle on the side panel about a foot off the floor means a slow cooker’s cord hangs down the outside of the island, through exactly the height where a child sits, and gets pulled. Most countertop appliance labels already say never to drape a cord over the counter edge or use an outlet below, so the code has caught up with what the appliance makers were already asking for.

If you install no receptacle, you still owe a rough-in

The easiest part of the new rule to miss, because it looks like permission to do nothing. The code language is that if a receptacle outlet is not provided, provisions must be provided for the addition of a receptacle outlet in the future. In practice that means a junction box, conduit or whip run into the island so an outlet can be added later without tearing up finished cabinets and a stone countertop. This is a genuinely sensible requirement and it is also invisible once the island is closed up, which means it is the item an inspector will ask about and a crew will have forgotten. Do it at rough-in, photograph it, and note where it terminates.

Where a receptacle is allowed, and which option inspectors prefer

Two locations are permitted under the 2023 code. Above the countertop, no more than 20 inches above the surface, which for an island with no backsplash means a raised bar, a ledge or a vertical column designed into the island. Or in the countertop itself, using an outlet assembly specifically listed for countertop installation, which is the option that suits a clean modern island and is common in higher-end work. Guidance notes that the above-counter option is usually the simplest to coordinate and inspect, because the receptacle ends up visible, accessible and familiar to the inspector. If you choose the in-counter route, the listing matters: it has to be an assembly listed for that application rather than a device adapted to it.

GFCI and AFCI did not change, and still apply

Easy to lose in the noise about what the 2023 revision removed. All receptacles serving kitchen countertops still require GFCI protection, and the branch circuits still require AFCI protection. Removing the mandate to have an island receptacle at all did nothing to the protection requirements for the ones you do install. Protection can be provided at the device or at the breaker, and the choice usually comes down to accessibility for resetting, which on an island is worth thinking about, since a GFCI device buried in a listed in-counter assembly is less pleasant to reset than a breaker in a panel.

Get the overhang limit from the fabricator before the box is built

An island with seating has a countertop overhang, and how far it can project unsupported depends on the material, its thickness and what is under it. That number belongs to the countertop fabricator rather than to the cabinet maker, and the reason to ask early is that the answer can require support inside the cabinet: corbels, steel brackets or a substrate, all of which are structural and have to be fitted before the top arrives. Asking after the island is built and the stone is templated is how a seating overhang turns into visible brackets nobody wanted or a reduced overhang nobody planned for. This is the same relationship as the flatness tolerance: the fabricator sets a number and the cabinet work has to satisfy it.

The floor is the wall, and the rough-in fixes the position

Attachment is the part of an island that is genuinely different rather than merely code-affected. With no studs to reach, standard practice is to mark the footprint on the finished floor, fasten cleats inside that outline, set the cabinets down over the cleats and screw through the cabinet sides into them. Get the footprint right before anything is fastened, because the plumbing and the circuit come up inside it and they are what really pins the island down. Confirm walkway clearances on all sides with the actual footprint marked out on the floor and the appliance doors in mind, since a clearance that reads fine on a plan can be defeated by a dishwasher door and a person standing at it.