Best part of having the welding supply do this for me is I don't have to mess with it, they go to every machine check it out, place a sticker on it and give me a written report to file with all the serial numbers and readings on it traceable back to NIST standards, they schedule it and do it all. All I do is OK their invoice and I don't mind when it is half of the cost of keeping up our meters.
John Wright