There is a new version of the EC-30 manual for version 3.15 and later (Not attached here because of copyright. The document is 0900-0541_I5_201504.pdf if you want to request it from Onan). I got it along with this explanation from ask.powergen@cummins.com:
The SP Sense option should be selected based on where your shore power sense lines are connected.
If the SP sense lines are connected to shore power before the transfer switch, the "Before" setting will not auto-start the generator set if it senses power, and will shut off the generator when it senses power. If the "Before" option is selected, you can then select if the generator will always start when it senses shore power lost and stop when it is restored (SP Loss "Auto"). Or if SP Loss "None" (page 8 says "Off") is selected, the generator will only start when it receives a low battery or HVAC signal.
If the shore power sense lines are connected "After" the transfer switch, the EC-30 will not be able to tell if the power is coming from the generator set or shore power. In that case it does not automatically start if AC voltage is present, and does not automatically shut off when it senses AC voltage. It does not allow you options for SP Loss starting.
SP Sense "None" is the same as the "After" above, and should be selected either if you don't have SP sense wiring, or if you're not sure where the SP sense wiring is located in the system.
Tom & Linda Bowe
Daisy the beagle
Former 7 year Full-timers, now home based in Blairsville, GA