Yacht encyclopedia
Galvanic isolator
Galvanic isolators on yachts: blocking DC shore-power paths, survey checks, and FairHelm limits on treating them as a cure-all for anode loss.
What this is
A galvanic isolator is a device in the AC shore earth conductor that blocks small DC voltages while still allowing fault current to trip protection, reducing galvanic currents between marina earth and underwater metals.
Anchor
Nordic winters mean months on shore power. FairHelm notes whether an isolator or isolation transformer is present, and whether the shore cable and inlet still look heat-damaged.
FairHelm judgment
FairHelm judgment: an isolator is strongly advisable for boats with underwater metals and long shore stays. It does not replace anodes or bonding. Isolation transformers are a heavier alternative on some installs.
Limits
We do not certify any brand here. Installation and testing belong to a marine electrician. Do not confuse an isolator with a simple earth lift that creates a shock hazard.
FAQ
Q: Does an isolator replace sacrificial anodes?
A: No. It reduces one shore-power path. Anodes and bonding still matter.
Q: Is an isolation transformer the same thing?
A: No. A transformer isolates more completely and costs more space and money. Both aim at galvanic shore issues.
Q: Can I leave shore power connected all winter without one?
A: Many boats do, and many waste anodes faster. FairHelm treats missing isolation as a survey talking point.