One you are asking about electrical systems not electronics. There is a
difference.

A "For Razors Only" outlet is not a GFI outlet, it is an isolation
transformer that makes it "safe" to use an electric razor next to a sink
with faucets. Straight out of the 60s. The only type of electric outlet
allowed in those days. It cannot handle power loads such as a dryer. Replace
it with a proper GFI receptacle.

If the bathroom was originally built in the 1950s to 60s, you can be sure
that the circuit cannot handle any extra load. Install a new 20 amp circuit
for your bathroom alone. It will then be able to handle dryers, exhaust fans
etc. etc.

wrote in message
...
I am renovating a bathroom and am planning on adding another light
fixture by running it off of an existing fixture.How can I be sure the
circuit can handle the extra load?

Also there is a plug that says "For Razors only".Is this a GFI box?

Thanks