The National Electrical Manufacturers Association (NEMA) has published NEMA LSD 56: Compatibility of Forward Phase Control Dimmers and Dimmable Self-Ballasted Compact Fluorescent Lamps and Frequently Asked Questions Regarding CFLs and Dimming.
 
This publication provides design guidance in the area of lamp/dimmer compatibility to the manufacturers of dimmable self-ballasted compact fluorescent lamps (CFLs) that use forward phase control and the manufacturers of forward phase control dimmers. The values provided assume operation under nominal line conditions, i.e., 120 V, 60 Hz. In practice, actual voltages can vary by ±10% in the field. LSD 56-2011 contains a related FAQ, which is meant to provide answers to frequently asked questions regarding CFLs and dimming.

LSD 56-2011 may be downloaded at no cost by visiting www.nema.org/stds/lsd-56.cfm. 

NEMA is the association of electrical equipment manufacturers, founded in 1926 and headquartered in Arlington, Virginia. Its member companies manufacture a diverse set of products including power transmission and distribution equipment, lighting systems, factory automation and control systems, and medical diagnostic imaging systems. Worldwide annual sales of NEMA-scope products exceed $120 billion.