it may not be exactly what you are dealing with, but might give you a frame of reference:
As you can see, the timer switch control is defined by "Y", "R", and "Q" switches on the diagram, what these switched do and when they time out is illistrated on the table below.
Lets go with a simple timed tumble dry, set the timer and push the start switch, the start switch is pressed with time on the timer, switched Y,R, and Q close, the centrifugal switch in the moter closes, giving you a latching ciruit (hold the dryer on once you release the start button)
Voltage from L1 travels through R and into the high limit and tstat connected, then it will enter termal H3. This may be where you are seeing your "bridge".
From the looks of this diagram, the 1500W element is always on as long as there is voltage suplied at H3 and H2, the operator will have a switch that will determine whether the 3700W element will engergize at EX3. Currently, this drawing seems to illistrate both elements engergized.
So yes, one side of your element should always have 120 volts of electricity going to it. This 120 volts will be on potential L2. When the proper switches are closed (high limit/t-stat, etc) you will suply L1 potential of 120 volts to the other side of the element. This will give the element a 240 volt supply. If you were to take the other side of the element and ground it, or run it to a neutural, or ground it, it wont work, infact, it might short out, and throw sparks.
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