3 way switch

Hi Bruce - it doesn't matter if the power is AC or DC, the wiring of a 3-way circuit is the same.  I'm guessing you've checked and double checked your wiring to the diagram you are using (I don't know, but perhaps the book has it wrong). If you post an email address I can send you a wiring diagram to try.  I would caution you that using inexpensive, readily available 3-way switches commonly used in the AC world could be a problem. They typically aren't rated for DC use. To be safe, I would recommend using a commercial grade switch and limit (by limiting the number of lamps and their current rating) the switching to a couple of amps.  The problem is that arcing in switches (happens in all of them), particularly when breaking contact, is typically quenched as the voltage passes through zero (in the AC cycle).  In a DC circuit, this doesn't happen.  Generally this means that the life of the switch will be shortened vs. AC use.  In extreme cases, it could be a fire hazard.  So limit the DC current you are trying to switch to well below the rating of the switch.  Anyway, let me know if I can help you with your wiring circuit problem.

Regards -

Tom Hardy, PE
HVTA, Inc.

dc switches are getting very hard to find.  I think we still carry one that I went out of my way to source for a cabin guy.  That one was only a two way switch.  let me know if you need one, or if you think we should have it on the website.

oh yeah, T rated switches will also work to the best of my knowledge.  the one we carry is  a surface mounted T switch, and it is ugly and brown, but safe for 12v dc situations. 

If I could avoid it, I would not use an ac switch for dc loads. 

Also, good ole square d "QO" circuit breakers are dual rated for dc usage up to 48 volts total.  for battery apps 12 or 24vdc is okay, for solar, we stick to 12vdc nominal only because of the possibility of going over the 48v rating.

- james Alt-E staff