I have fire alarm wiring from two different sources (i.e. EBDK and a fire alarm), but only one fire alarm contact input on the ELTS2.
It is important that only one pair of wires is landed on the fire alarm contact input on the ELTS2. Varying voltages on the fire alarm contact lines will cause issues if two different sources are landed on the same header.
Find a way to reduce the fire alarm wiring to one pair of wires before it touches the ELTS2. Recommendation for the above example would be to land the fire alarm's wiring to the fire alarm input on the EBDK. Then use the output wiring from the EBDK to land on the fire alarm contact input on the ELTS2.