220v acceptable range from power co.?

[jderou]

What is the acceptable range of voltage, for 220v, coming into a home? I have been told 10%, but is it 10% of 220v, or 240v?
Mine is measuring 250v, and I can't keep transistors from blowing.

[pastera]

The range is normally ±10% of 240v = 264 Vrms (at +10%) = 374Vpp (at +10%)

The supplied line voltage (and tolerance) depends on the country you live in. Just give the local power company a call, they will be able to help you and will send someone out if you do have an overvoltage condition.

My line voltage runs ~210-234 depending on time of day and outside temperature (damn air conditioners). This is a very large differential considering I live less than 3 miles from the local power plant.

For 220v applications, 600V transistors are called for to allow for spikes in the line voltage (load dumps). You can get away with 500v transistors with good snubbing.

Aaron