Your house wiring probably doesn't have to live at 140 degrees F & have salt-water splashing around. Probably doesn't carry 30,000 volts either...

I don't replace my plug wires 'just because' of age or miles. There's 2 ways for plug wires to go bad.

1) Resistance. Measure with a multi-meter.

2) Insulation breakdown. Run the engine & watch the wires & distributor cap when it's really dark out. Look for arcing, a dull blue glow. Works better with a completely cold engine, spray water from a windex bottle for even better results. Replace anything that shows any arcing.

ps... ever see the kind of house wiring they used 100 years ago? You might want to replace it after all.