On Sat, 09 Apr 2011 14:42:39 -0700, David Nebenzahl
wrote:

On 4/9/2011 2:30 PM A. Baum spake thus:

An amp meter goes in series with the secondary (or primary) of the
transformer. You can convert amps to volt-amps by multiplying volts times
amps. 24 volts times 1 amp = 24 volt-amps. I don't remember if
transformers are rated differently for the primary or secondary or which
one is usually used. It might be in the technical data usually packed
with the transformer or stamped on the transformer somewhere.

Using the primary side would be more conservative (= a bit safer), since
it will include any losses between primary and secondary sides. But it
really doesn't matter. And I'd much prefer to measure current on the
secondary side, rather than deal with 120-volt juice.

He still has the problem of finding an AC ammeter, since a DMM won't
handle AC current.

As noted previously, this is NOT the case. An AUTOMOTIVE DMM might not
have an AC current scale, but virtually all general purpose meters do.
They generally have a "third terminal" used with the common for the
high range, which will be what he wants to use since the low range
that uses the standard (vom) connections generally tops out at 300ma,
more or less.