You might think it’s a good idea to skip baseline testing in an effort to save money. But taking this approach actually is a costly mistake.
A core concept in baseline testing is that results show the condition of equipment when it's new and in normal condition. If you wait a year before testing that equipment, your test results may be reflecting an abnormal condition that developed during that year of service. The problem is you won’t know it’s abnormal.
For example, you perform insulation resistance tests on a motor when it's installed. The test results are absolute values and by themselves usually don't tell you very much. There's not a spec that says the insulation must be X ohms or it's deteriorating.
When you perform the test a year later and the readings are similar to the baseline data, you can be reasonably confident that insulation is good. Reasonably confident as opposed to confident, because no single test can tell you with 100 percent certainty that the insulation is good. At least this test didn’t tell you the insulation is bad.
But let's say you waited a year to get the baseline data. During that year, the insulation had been damaged. All you have from your test are absolute values and nothing to compare them with.
If it turns out that Joe Smith snuck in during lunch and got baseline data the day the motor was installed, now you can compare the data you just took. Yay for Joe, but it’s unlikely any such person exists. Make sure that baseline testing data are always taken.
Baseline test results serve as a standard for comparing time in service results.
A few flies exist in this ointment, however. One such fly is the fact that you need an ample battery of tests. In the typical maintenance department, nobody has the expertise to determine what these are. For a new installation, the typical maintenance department should hire a qualified electrical testing firm to make that determination. Then also have them spell out exactly by what method and with what equipment settings subsequent testing must be performed so that anomalies that arise because of testing method variance are eliminated.