Correct transformer voltage settings

[Kitchener]

I’ve been reading the Crack manual (kit is in the mail!).
And I’m quite uncertain what voltage settings I should use for my Crack.

Our national power grid is supposed to deliver 230 Volts, but this can vary up to 10% either way.
I could measure the voltage in my house and set the transformer according to that, but I intend to use the Crack at my office as well.
So considering that the voltage in my house and my office could potentially vary a bit, what setting should I use for my transformer?

Should I use the “GREATER than 225V AC and LESS than 235V AC” setting?

[Paul Birkeland]

You should get a meter and measure the voltage at both locations.

-PB

[Kitchener]

Yeah but even so, what if both locations measure 230 Volts and that's fine for a while until I move it someplace where the voltage differs to a greater extent?

What are the risks of using a Crack attuned for 225-235 Volts in a socket with 210 or 240 Volts?

Is it in some way safer to set the Crack for a higher voltage than the socket provides i.e., safer to have the amp set for 240 volts with a socket providing 220 volts than an amp set for 220 volts with a socket providing 240 volts?

[Paul Birkeland]

Let's address that issue when you actually have it.

I have been at this a long time and helped quite a few overseas customers, and I haven't ever run into a 210V situation.

In my experience, you are likely going to need to move to a different country to get the kind of line voltage deviations that are currently concerning you.

-PB

[Kitchener]

So what you're saying is that I should definitely pack my Crack in the car and go on a cross-Scandinavia/Northern Europe tour so I can find an outlet that delivers either 220 or 240 Volts just so I can say "see? See!? Told you this would be a problem!"? 

EDIT:

While we're on the subject of measurements; is a standard cheapo multimeter good enough for inspecting the Crack?
-the included image is of a $30-35 meter.

[Paul Birkeland]

Sure, that will certainly get the job done.

[Kitchener]

So I've measured the voltage at home and at the office.

Home: 240
Office: 230

So I need to choose wether to assemble the Crack for 225-235 Volts or 240 Volts and up.

Is this a big deal? What sort of problems can I run into if I use the wrong setting?

I want to use the Crack at home and at the office.
Mostly at the office, I think.
-I'll probably just bring it home over the holidays.

But I will naturally be assembling the Crack at home, with 240 Volts.

Sooo, what do I do?

[Paul Joppa]

For perspective, remember that these power line voltages have always been variable. Most tubes are designed to work with voltages that deviate from the nominal by +/-10%. Wired for 240v, you can expect acceptable operation over the range 216v to 264v.

[Kitchener]

Okay, thanks that put me at ease.
All the options made me kind of nervous!