Is it normal for a 4-prong dryer outlet to have two white wires?

That setup is a clear **code violation** and almost certainly the result of a "flipper special" where they didn't want to spring for a roll of 10/3 Romex. A NEMA 14-30R outlet requires two 120V hot legs, a dedicated neutral, and a ground. It sounds like they used 10/2 cable (which only has black, white, and ground) and then illegally pulled a separate white wire to act as the second hot or neutral. Or worse, they just grabbed whatever scrap was lying in the van.

The reason this passed inspection is simple: home inspectors don't pull outlets. They carry a plug-in tester or a multimeter, check that the voltages look correct at the slots, and move on to the next room. Unless there is visible charring on the faceplate or the outlet is physically falling out of the wall, they aren't going to see what's going on behind the scenes. They assume the wiring was done to code when the house was built or renovated.

You cannot legally use a white wire as a hot in this gauge unless it is permanently re-identified with black or red tape at both ends, and even then, you can't just run a single loose conductor trough the wall to make up for a missing wire in a cable assembly. If those white wires are just loose in the wall or coming from diferent cables, you have a major risk of induction heating if they aren't bundled properly.

I whould strongly recomend pulling a new, proper 10/3 cable from the panel to that outlet. If they cut corners on the dryer circuit, there is a high probability they did the same thing elsewhere. Check the breaker at the panel too; you want to make sure it's a dedicated 30-amp double-pole breaker and that those white wires aren't just doubled up on a lug they aren't rated for. Using it as-is is just asking for a harness to melt or a fire to start inside the wall where you can't see it.

Man, flippers'll do anything to save a buck. I’d bet money that extra white wire's just some scrap they found in a junk pile. You really gotta check the panel and see where that second white's acutally landed. If they're using two seperate cables to make one circuit, it's a mess. I wouldn't even trust the breaker labels at this point. Better grab a toner or start tracing 'cause who knows what else they've hidden behind the drywall. It's ussually never just one 'oops' with these guys.

Totally agree, that's a classic "flipper special" death trap. One thing to look at while you're in there is the actual box depth. When people hack multiple 10/2 lines into a standard shallow single-gang box, they ussually have to crush the wires back to get the outlet flush. With 10-gauge wire being so stiff, that puts massive mechanical stress on the terminal screws. I've seen those screws loosen over time just from the constant tension, wich leads to arcing and localized heat before the breaker even thinks about tripping.

Oh man, this is wild! I'm just getting into DIY electrical stuff and this thread is pure gold. I'm actually moving into a place next month and now I'm terrified to look behind my outlets! Since those white wires are carrying a load, does that mean the dryer whould actually run normally til somethig melts? Also, speaking of wierd setups, are those 3-to-4 prong adapter cables you see online basially doing the same sketchy thing with the ground and neutral? I’ve always wondered if those are just a 'flipper special' in a box or if they're actually safe to use in a pinch.

Quick update—I checked the panel like suggested and it's a total hack job. They used two seperate runs of 10/2. One white wire is hooked to the neutral bar, while the other is actually wired into the double-pole breaker. The box is also incredibly shallow, so the wires are definitely pinched. Since this is a 'death trap,' shoud I just pull the wires out entirely for now?