Re: Is there a heat coil equilibrium point?

There is indeed an equilibrium state, reached when the thermal power into
the coil (given by RI^2) is balanced by the thermal power lost to
convection of the surrounding air (given approximately by C(T_coil -
T_air), where T_coil is the temperature of the coil, T_air is the
temperature of the surrounding air, and C is a constant that is related to
the coil surface area, the density and temperature of the air, etc etc
etc.).  In principle, solving for this equilibrium temperature will be
easy, but in practice you would almost certainly be better off attaching a
thermocouple to your coil and then manually adjusting the current source
until you get the precise amount of coil current necessary to give you the
160-degree equilibrium temperature.

While AC voltages can (and sometimes do) vary significantly from outlet to
outlet, I am curious why you think that DC power supplies plugged into
those same outlets would not be similarly affected.  In any case, the
voltage variations in your local AC outlets should be quite small -- large
variations can damage or destroy some electrical equipment.