Two hot wires in a junction box: trace the dead circuit

Short answer: no. A split-tab receptacle added in that outdoor box powers only itself, because the box ends its cable: both hots sit capped and nothing continues toward the kitchen. Capped red and black with a single white is either a spare pair on opposite legs or a terminated run. At a 120/240 V split-phase service the pair reads 240 V AC hot to hot on opposite legs and 0 V AC on the same leg. The dead outlets belong to a different cable, and you find that fault from the panel inward: the 20 A breaker, then any GFCI in the chain, then the last receptacle that still works.

What two hots and one white can be

A duplex receptacle carries a small tab between its two brass screws and a second tab between the silver ones. Snap off the hot-side tab and each half takes its own hot; that is a split-tab receptacle. The tab splits one device, nothing beyond it. For two halves to share one white safely, their hots sit on opposite legs of the service and disconnect together. That shared-neutral arrangement is a multiwire branch circuit, fed from a handle-tied breaker pair.

The green or bare conductor is the equipment grounding conductor, never a current-carrying leg. An insulated one of 6 AWG or smaller is green or green with yellow stripes under NEC 250.119, and it bonds to the box, not to the white; the grounding and bonding guide carries the detail. When conductors are hard to tell apart, the walkthrough on finding the hot wire among look-alike whites sorts them by reading, not by colour guesswork.

Feeders on, the meter settles what the capped pair is. A healthy hot reads about 120 V AC to white on a live circuit:

Either way, the capped pair feeds no load, so it cannot be what darkened the kitchen.

Why an added outlet cannot power the kitchen

Power reaches a receptacle through conductors that arrive and continue. Feeding two kitchen outlets from this spot takes a cable leaving the box toward them, with hots, white and green all running through. This box has no outbound cable; the hots end capped on a terminated run. A device added here taps what the box carries and stops there.

A GFCI protecting downstream receptacles shows the same limit from the other side. It needs line conductors in, load conductors out, and the white it monitors running with it. One capped white cannot serve that pass-through. The dead kitchen outlets ride a different cable, and their fault sits at or upstream of the point where that cable last worked.

What each symptom points to

• Two counter outlets dead, the rest of the kitchen alive. Both hang downstream of one point: a tripped GFCI or a loose splice at the last working receptacle.
• Every countertop receptacle dead at once. The kitchen breaker tripped, or the first GFCI in the run tripped.
• Breaker handle looks on, outlets still dead. Another GFCI in the chain tripped; sweep kitchen, garage, exterior and basement units before opening a box.
• 240 V AC across the capped pair, everything else fine. A multiwire tail or a 240 V spare; label it and leave it capped.
• One half of a duplex dead, the other half live. A snapped-off tab or a burned half inside that one device.

The causes, most likely first

1. A tripped GFCI upstream. Kitchen receptacles sit behind GFCI protection, and a Class A GFCI trips at 4-6 mA of leakage, long before the breaker cares. One damp cord or failing element kills everything downstream of it. Device choice for receptacle circuits is its own subject; the walkthrough on selecting GFCI protection for industrial receptacles compares the options.
2. A tripped breaker. Two 1,500 W appliances on one circuit draw 3,000 W, and 3,000 W ÷ 120 V = 25 A, five amperes past the breaker's rating. Unplug the load, reset the breaker, and the run returns.
3. A loose connection at the last working receptacle. Push-in backstab terminals loosen across heat cycles, and everything past that point dies together. Browned insulation or a burnt smell marks the box.
4. The outdoor pair, an innocent bystander. Capped spares end their own run and feed nothing, so they cannot darken the kitchen.

How to check each cause

1. Sweep the panel. Look for a tripped kitchen handle and reset it from its middle position: off first, then on.
2. Sweep the GFCIs. Press RESET on every GFCI between the panel and the dead outlets; the counter receptacles return the moment you find the tripped one.
3. Test at each receptacle. A plug-in receptacle tester shows correct wiring, an open ground or a dead unit in one look; mark where the run stops working.
4. Read the outdoor box. Take the table's readings with the feeders restored: hot to hot across means opposite legs, zero across means same-leg spares.
5. Open the last working receptacle. Inspect for backstab connections, loose screw terminals and browned insulation before touching anything further.

The shared-neutral math: two 1,500 W halves on one white

The inputs: two 1,500 W halves, a kettle and a toaster at typical countertop ratings, used as example values here, on one split receptacle fed at the 120 V leg. The neutral is 12 AWG copper, and the breakers behind the box are the 20 A units. Divide power by voltage for current, I = P ÷ V. On a shared white, opposite-leg currents subtract and same-leg currents add.

Each half draws 1,500 W ÷ 120 V = 12.5 A. On the same leg, the single white carries 12.5 A + 12.5 A = 25 A. On opposite legs it carries 12.5 A − 12.5 A = 0 A at balance, and only the imbalance otherwise. The same-leg case therefore puts 25 A through a neutral sized for the 20 A circuit while each breaker sees just its own 12.5 A: nothing trips, and the white overheats.

That arithmetic is the decision. A shared white belongs only across opposite legs on a common-trip pair, and the NEC treats a multiwire branch circuit as one set that disconnects together. Split a receptacle any other way and each half takes its own neutral, with a double-pole breaker where the halves are separate circuits. Watch the threshold the same way: on one leg the white carries the sum, so it passes the breaker rating as soon as the halves together exceed 20 A, just over 10 A each.

The fix

Work from the panel inward and stop when the tester shows line voltage at the dead pair. Reset the tripped breaker, clear the tripped GFCI, and retest. If the run stays dark past those two, open the last working receptacle: move any push-in conductors to the screw terminals, remake tired splices with fresh wirenuts, and pigtail where two conductors share one terminal. The piece on two wires on one terminal shows when a lug or a pigtail is the right move. Restore power, test both outlets, and confirm the outdoor box still reads per the table before closing it up.

Anything past reset-and-test, such as a multiwire to trace, a burnt splice inside a wall or a new outdoor circuit, belongs to a licensed electrician.

Stop it coming back

Label the capped pair while the cover is off: 'spare — 240 V across' on opposite legs, 'spare, same leg' otherwise. The next person to open the box deserves to know before a wirenut moves, because breaking a neutral on a live multiwire circuit puts a shock hazard through whatever load shares it.

Outdoor hardware then keeps the box dry for good. Use a weather-resistant GFCI where the location calls for one, and an in-use cover that shields the contacts with a cord plugged in. Seal every entry the way the mounting details demand; the walkthrough on mounting a weatherproof box without losing its rating shows where installations give the rating away.

Receptacles stay in listed residential boxes. When a spot like this houses controls instead, such as a small controller, a supply or a relay bank, the job becomes enclosure work. A 304 or 316L wall-mount enclosure, manufacturer-rated NEMA 4X / IP66 and not UL listed, is cut to the layout you order and delivered in 10 business days from drawing approval. Adding a receptacle inside such a box carries code points of its own, covered in the walkthrough on wiring a receptacle inside a control enclosure. Pick the rating with the outdoor enclosure guide, then send the layout through custom enclosures.

Catalog dimensions to compare

Compare these catalog dimensions with your component layout. Open each enclosure for its rating, material and usable space, then check those specifications against your application.

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