Enough already ?
Enough already ?
	
		
	
	
		
		
			000  ON
001  OFF
011  ON
010  OFF
110  ON
111  OFF
101  ON
100  OFF
		
		
	 
Have not seen a boolean / truth table since 1985, 
last time I graduated.   
Well, I guess they are part of the PLC designs, 
just don't look the same. 
In a jam,  I have wired whole circuits with 4-ways,  
only mistake was to make connections side-to-side   :happyno: 
You could carry a neutral in the cable,  
then energize a lite at every-other switch,  
alternating the lighting scheme down the long hallway.  
Seems silly.   :lol:
Today, I get to check beeping signals from a UPS on a telephone system. 
Better get going.   
Hope it is an arcing OCPD, or loose connection,  
anything worth fixing.