The phase voltage in a wye-connected device is 277 V. What is the line to line voltage?

Question

I think it's 277v, because line to line on a wye should be the same one of the phases.

Answer 1

Your las answer is correct, but  just remain that if the say phase voltage is line to ground voltage, but if they dont say wheter it is phase or line to line you are gonna take the line to line voltage which is commonly used to describe this kind of things.

Answer 2

The line-to-line voltage is always greater than the line-to-neutral voltage; think of the phasor diagram.

The factor is sqrt(3), so the line-to-line voltage is 480V. Third time lucky. :-)

Answer 3

I'd go with your last idea, 480V  "third try is a charm" (an old saying)