Photons have zero rest mass, however when in motion they have a non-zero mass as does all forms of energy including charge.
***Photons are never at rest. They have momentum but not mass. Charge is not a form of energy.***
That does not prevent them from moving at the speed of light.
A charge is a standing wave. It is moving at the speed of light as made evident by the propagation of any variation in its field strength.
***ha ha. Chagres are electrons and protons: Particles, not waves***
A charge field is caused by interference between multiple emitting sources. Wave interference diminishes the wave strength with distance causing the energy of propagation to be trapped a specific density shape.
***Charges that accelerate propagate EM waves or light, same thing. You are confusing light with matter***
In this way the waves propagate outwards continually and of course eliminate one another continually causing the apparent containment of the field. The field does not totally dissipate with distance but the majority of the field is contained within specific boundaries defined by the field equations.
***What pray tell are the field equations for charge. Certainly not Maxwell's***
When the emitter wave intensity is increased, the field strength change propagates outward at the speed of light. After the field in a location has attained its new intensity it remains in an apparent static condition as long as each wave propagation is of identical properties.
***ha ha ha***
The emitters must of course be directional and parallel path, with 180 degree out-of-phase waves they must also have identical wave length and intensity to be efficient at this process.
*** More ha***
You asked if I made this up?
Yes... I just invented radio technology yesterday. ( I wonder if I can get royalties? )
***Ha Ha ...***