Can you recommend an accurate meter for warranty tests?
We like the Hioki Hi Tester. It is an affordable and accurate digital meter that we use to perform warranty tests and trouble-shoot problems with out local customers in Chicago. 

In fact, we like it so much we started selling it. 

You can use it to perform the following test:
-Insulation Resistance Readings (Megger)
-AC Voltage Readings
-Total Resistance Readings

Remember, the proper tool can save you time and money. For only $440 (list) you can provide an affordable meter to your customers. 

 Tip From The Field
 Contractors often find themselves stuck on a job-site without a working  meter.

 As a value-added service, we keep a Hioki meter in our office and loan it out for a $200 deposit.

Since every meter is different, they really appreciate that we can show them how to perform all of the tests when they pick it up.