An anecdote on the power factor issue was sent to me ... Apparently a company in the UK installed a large number of CFLs in a building where the lighting was primarily on one phase. It burnt out the neutral link in the fuse box and caused a small fire! The high peak current of all non-power factor corrected CFLs can cause problems where they are used in large numbers. For example, 25 x 75W (incandescent) lamps will draw 7.8A - just within the 8A rating for lighting circuits in Australia. The power factor is 1 because of the resistive load. If replaced by 25 x 13W CFLs, although the RMS current is lower, the peak current is over 10A (based on the 410mA peak current as shown in Figure 11). No problem at all so far, but ...

What if the installer decides that many more lamps can be connected to the circuit because of the lower power? Based on the claimed RMS current for a typical 13W CFL (~95mA is typical), it would seem that you can run 80 CFLs on the same lighting circuit (80 x 95mA = 7.6A). Unfortunately, the peak current is 80 x 410mA = 32.8A. The wiring won't overheat, but in-line connections (junction boxes), switches and other terminations may fail because they are expected to handle the high peak current continuously - well above their design ratings (especially if a connection is very slightly loose). Remember too that the switch-on surge (inrush current) will be many times higher again - if we assume only 4A (fairly low in reality), the first cycle inrush current could be as high as 320A if all lamps are turned on at once!

Things can be worse if the lighting is spread across a 3-phase system. With resistive loads, the current in the neutral wire will be zero if all 3 phases have equal loading, or up to a maximum of the current in one phase if the load is spread over one or two phases (or is not balanced). With non-linear loads, the neutral current can be as much as double the phase current. This is a real problem with non-linear loads, because many wiring codes allow the neutral conductor to be smaller than each of the phase conductors!