We present the results of an experimental study of the He I 492.2 nm line with forbidden components emitted by low-electron temperature and high electron number density helium plasma with or without addition of hydrogen. The shapes of the He I 447.1 nm and 501.6 nm lines and hydrogen Hβ line were used to measure electron number density in the range (1–5)×1023 m−3, while electron temperatures in the range from 25,000 K to 35,000 K were determined from the line to underlying continuum ratio of He I lines at 388.8, 667.8, 706.5 and 728.1 nm. The experimental profiles of the He I lines are compared with the results of a computer simulation method. The comparison was performed by use of a program for simultaneous interpolation of data tables obtained by computer simulation for 492.2 and 501.6 nm He I and hydrogen Hβ lines. The electron number densities obtained from this comparison agree within 10% with corresponding values determined from the 447.1 nm He I line which is well within theoretical and experimental uncertainties for all lines included in comparison