Most home lighting circuits (that I have seen) have a 15-amp breaker (/fuse) and have 14-gauge wire as it can be a bit of a PitA to work with 12-gauge wire in multi-gang boxes with 3- & 4-way switches and dimmers. Also, in an unmodified (IOW, no additional fixtures added) lighting circuit, the expected electrical requirements are easy to "forecast."
Adding a power-strip and plugging electrical devices into it can quickly use up the capacity of the lighting circuit - especially if one of the things being plugged in is the ballast to a HID light (if that ballast is a C&C which may draw significantly more power at startup than when running, such as a 400-watt one drawing 572 watts when it fires).
It's not unheard of in houses that have those older-style porcelain fixtures for an owner to occasionally use the outlet and blow a fuse every time - and then to replace the 15-amp fuse with a 20-amp one, thinking that there won't be problems later. Then the owner sells the house, doesn't think to install the proper (lower-rated) fuse, and suppose for a moment that the new owner has a power-strip, lol.
I would never install a higher-rated fuse than specified, but some people do. The fuse (or breaker) should always be the weakest part of the system so that in case of a problem, it will be what breaks. (I learned my lesson when I used to do a little racing. Hit 20psi boost for the first time, blew head gaskets. Got "smart" (NOT) and replaced them with a pair (to maintain proper height) of stacked steel gaskets on each side. Then over-boosted. It wasn't a head gasket - or even two - that blew that time, lofl... <COUGH> I became the newest member of the DOtC (Driven Over the Crank) Club. 275 miles from home with no truck or trailer because, hey, I drove to the track. Whoops.)
If it were me, at minimum I would flip off the breaker (or remove the fuse) for that circuit, go through the house from top to bottom checking to see what is powered by that circuit, and attempt to figure out the load on the circuit. If it is a shared circuit with both lighting and outlets, you'll have to guestimate the expected loads to be plugged in to those outlets. Figure 80% of the rated capacity of the circuit for a reasonable - and safe - target.
The little circuit breaker button on those power-strips probably won't ever come into play in such an installation; if the strip is rated for 15 amps but the entire circuit is also rated for 15 amps, you'll overtax the circuit before you overtax the power-strip. You may or may not notice the wiring heating up along the way from the end devices back to the circuit (but if there is substantial load, it probably is heating).
Also keep in mind that the outlet on the porcelain fixture may not be properly grounded (even if it's a grounded outlet). Such an outlet should, IMHO, be treated the same as one of the outlets on a light-duty two-wire extension cord. Safe to use - if used safely.
Just rambling.
