I live in a region where standard mains voltage is 220 volts. Recently I tried to measure it using a digital multimeter. The multimeter specs say that it has maximum error of 1,2 percent of the displayed value plus 3 units (volts in my case).
So I measured and got 241 volts which kind of scared me. According to the specs maximum error would be
241 * 1,2 / 100 + 3 = 5,892
which is about 6 volts, so the real value is in range 235..247 volts which scares me even more.
The spec further says that the maximum error is only guaranteed for the first year of the multimeter lifetime which implies that the error might be even greater as the multimeter gets older.
My question is - how much worse will the error become? The multimeter is something like 5 years old now - what measurement errors should I expect?