Do the numbers. Each light string would have some labels
that provides number of watts. Total that wattage for all three
strings.

At minimum, building wire would be rated for 15 amps or 1800 watts.
Derate that maximum to something like 1000 watts (since fixture really

is for lower currents). Still, that electric source from a light
fixture
should be well above what your light string would consume. Again,
don't take anyone's word for it. Do the numbers. That is why a label
must be adjacent to every appliance connection to mains - so that you
will read those numbers.

Meanwhile, code demands that there be at least one outside
receptacle. Code even says how high from the ground, etc that
receptacle must be located. What year was this townhouse
constructed?

PM wrote:
Ok, so here's the deal, I live in a rented townhouse that does not have
an outdoor outlet. I used to run an extension chord in through the
kitchen window to a surge protector but that means my window is not
locked and also lets in cold air. Last year I bought a light socket to
outlet converter and put it in my porch light which I then ran my
extension chord to. I was considering doing it again but I'm concerned
that there is too much electricity running through my setup for it to
be safe. The wiring coming out of the light is just two small black
and white wires and I'm afraid that I might overload them and start a
fire. Does anyone have any advice on this? I usually string 3 or 4
sets into the outlet.