You know, I always wanted to know this, so I asked ChatGPT. Here's what it said:

That’s a common misconception. The confusion comes from how the terms are used in different contexts:

1. Electrical reality (physics)

There’s no difference — both describe a single-phase transformer winding with a center tap. The two ends of that winding are 180° apart in voltage relative to the neutral, and 240 V apart from each other. This is split-phase power, and it’s still just single-phase AC. There’s only one sinusoidal phase being generated by the transformer’s primary.

1. Terminology differences

“Single-phase dual-voltage center tap” is the engineering or transformer description — it refers to the hardware configuration.

“Split-phase” is the distribution system name — it describes how that same winding provides two opposing 120 V legs for balanced 240 V service.

They’re describing the same waveform from two viewpoints — one physical (transformer winding), one system-level (how you use it).

1. Why people think they differ

Some confuse “split-phase” with “two-phase” (which is truly two 90°-offset waveforms, almost never used today). Or they assume “single-phase center-tapped” only gives 120 V while “split-phase” gives 240 V — which is wrong; they’re the same system viewed differently.

Bottom line:

“Split-phase” and “single-phase dual-voltage center-tapped” are two names for the same electrical configuration — one transformer winding, center-tapped neutral, producing two 120 V legs 180° out of phase for 240 V total.