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Old 01-23-2011, 10:28 AM   #1
Jul 2007
Oceanside, CA
Posts: 1,204
Liked 121 Times on 90 Posts

Okay you don't have to be an EE but it is beyond basic stuff.

I have rewired my control panel to control 2 elements and the pump at the same time, by adding some switches. I think the switches are SPDT with center off. One switch chooses either the pump or the HLT element. The other switch chooses the Keggle element and I have nothing on the other pole.
Both elements are controlled through a contactor switches and one has an SSR.

I want the other pole on the one switch to be able to turn on both elements, so I can run the elements and pump at the same time. One problem I am having is the added wire to the contactor will allow the current to run back to the other contactor when I am trying to run just one element at a time.

I have come up with a way to isolate the current but it uses a relay switch. I recall diodes can operate as an electrical check valve to ensure electricity can travel only one way. Can a diode be used in line to prevent the current from back tracking along the wiring?

From my limited knowledge, (web research) I know i need a resistor for use in A.C.. Is putting a diode in line a good idea, or should i just go with the relay switch? If a diode will work which diode/resistor will be appropriate for running this contactor?

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Old 01-23-2011, 11:58 AM   #2
Mar 2010
Charlotte, NC
Posts: 3,336
Liked 302 Times on 235 Posts

A diode setup to control the relays will not work as the control circuit is 120V AC thus the current flows in both directions. The diode only blocks flow in one direction.

The easiest solution for you is to replace the selector switch (SPDT - center off) with a DPDT - center off switch. This way each relay contactors pick coil is isolated one from the other.

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