12. Multi-Stage SPD Coordination · Page 2 of 5
Distance Between SPD Stages
Cable length as intentional decoupling.
Rule of thumb
Many coordination schemes assume a minimum cable length between stages (often on the order of several meters) unless a dedicated decoupler is used.
Short feeder problem
When SDB is only a meter from MDB, verify coordination explicitly—do not assume datasheet Up values alone guarantee staging.
Designers' note
Show both SPD locations and approximate feeder lengths on the single-line diagram.