Why did my kid's bedroom outlet melt while using a space heater?

That's a classic case of a high-draw appliance meeting a weak contact point. Most of those old splitters or 'cube taps' weren't designed to handle a continuous 12.5-amp load, which is what your typical 1500-watt space heater pulls. Even if the splitter claims it's rated for 15 amps, that's often a peak rating, not a rating for a device that's going to be drawing max power for hours on end. What happened here is a **loose connection** inside that adapter. Over decades, the metal leaves inside lose their spring tension. When you plug in a heavy load like a heater, that loose fit creates resistance. Resistance generates heat, and becasue space heaters run for long cycles, the temperture just climbs until the plastic starts to fail. Your breaker didn't trip because you weren't actualy pulling more than 15 amps; you just had a localized heat source right at the plug point. It's a good sign that the house wiring looks clean, but you need to be careful when you replace that outlet. Don't buy the cheapest residential-grade receptacle at the hardware store. Spend a few extra bucks on a **spec-grade** or heavy-duty outlet. They have much better internal clamping force, which prevents this exact type of failure from happening again. Also, the cracked phone charger block suggests that heat was soaking through the entire metal frame of that splitter. It’s lucky it didn't start a structure fire. Moving forward, just make sure that heater goes directly into the wall—no adapters, no extension cords, nothing in between. If the wire in the wall box isn't charred or brittle, swapping the outlet for a high-quality one shoud make it perfectly safe.

That makes sense about the tension wearing out. I honestly didn't realize those little metal clips inside coud just get tired over time. Quick question on the replacement—is there a better way to wire it? I've seen some where you just poke the wire into a hole in the back, but other people say to wrap them around the screws. Does one way hold up better for heavy stuff like heaters? I realy don't want to deal with another melted mess.

definately avoid those push-in holes on the back, often called 'back-stabbing.' They rely on a tiny spring clip that barely touches the wire. For something drawing 12+ amps like a heater, that's just asking for another melted outlet.

When you get that spec-grade outlet, look for 'back-wire' terminals where the screw actually clamps a metal plate down onto the wire. It gives you the most surface contact. If you can’t find those, just loop the wire around the side screws clockwise. You want that connection as tight as possible so you don't get any arcing or resistance heat like you did with that old splitter.

Don't forget to check the plug on the heater itself before you use it again. If it was sitting in that heat, the metal prongs might be oxidized or warped. Plugging a damaged plug into a brand-new outlet is a quick way to ruin the new hardware becasue it won't make a clean connection. I'd also pigtail the wires if you've got multiple sets in the wall box. Instead of using the outlet to bridge power to the next room, tie the wires togehter with a wire nut and run a single pair of 'tails' to the outlet itself. It keeps all that heater current from flowing thru the outlet's metal tabs and stressing the rest of the circuit.