On a 15 amp, 14 ga wire, I was told to install no more than 10 fixtures. Suppose I use Low-Energy bulbs (23 watts = 120 volts) can this amount be increased?

Technically speaking, there is no NEC Code that restricts the number of outlets for residential use.

The NEC Codes for Commercial installations might limit the number of outlets to ten.

The critical limitation is wattage.

Voltage X Amperage = Watts. 120 X 15 = 1800 watts.

If you exceed the wattage, then you must go up in amperage which will increase your available wattage. In your case, 20 amps.

However, I wouldn't recommend going to 20 amps, if it could be avoided. You would have to replace all of the 14 AWG cable with 12 AWG cable and of course the breaker would have to be a 20 amp breaker.

What I have no way of knowing is whether the light fixtures would accommodate 12 AWG wires.

Yes, it does answer my question. By using low-wattage bulbs, I can increase the amount of fixtures, as long as I stay under 1800 watts, or 80% of that. Thanks, Chaz