Sterling Galvanic Isolator 130A – Zinc Saver – Pro Save W – Waterproof marine galvanic isolator for corrosion protection
The Sterling galvanic isolator 130A is a fully waterproof and highly redundant device that provides protection from galvanic corrosion, and from short circuits and power surges in your vessel.
Please note: Sterling Power uprated this device from 110A to 130A some years ago. They have not updated the labels on the device, which still indicate 110W. Despite the label, this device is indeed rated to 130A.
Why do you need a galvanic isolator?
Galvanic corrosion happens to all metal components on a boat that are exposed to seawater. Normally, your sacrificial anodes are enough protect your shaft and propeller from galvanic corrosion. However, when you connect to an onshore electrical hookup, safety demands that you also be connected to an onshore ground. This essentially creates a low voltage battery, incorporating your boat, the water, and the ground. Without any sort of protection, the current flow through this battery will significantly speed up the galvanic corrosion process.
You can protect against this battery effect by installing either a galvanic isolator or an isolation transformer.
Galvanic isolators and isolation transformers
Both galvanic isolators and isolation transformers achieve the same thing. They isolate your boat from the low voltage battery effect, protecting underwater metals from corrosion and preventing your sacrificial anodes from wasting too quickly. The difference is in how they achieve this.
A galvanic isolator is a small, lightweight device that prevents low voltage currents from passing between your boat and the shore. Because the battery effect current is generally less than 1V, it can’t pass, and your boat is protected. At the same time, high voltage currents, such as those that happen during a short circuit or power surge, can safely pass through to the ground.
An isolation transformer achieves protection by creating a physical separation between your boat and the onshore hookup. They replace the wired connection with an electromagnetic connection – power passes through the air by an electromagnetic field. This physical gap prevents the low voltage battery effect from occurring.
Galvanic isolators and isolation transformers – pros and cons
A galvanic isolator is significantly cheaper and simpler than an isolation transformer. This simplicity results in a tradeoff in reliability. Galvanic isolators are prone to damage by surges and lightning, meaning that you need to periodically check your isolator to make sure it’s still working. An isolation transformer is very resilient to power surges and lightning strikes – it’s an ‘install and forget’ device.
Additionally, galvanic isolators can only protect against currents lower than 1.4V. When connected to a shore hookup that’s working properly, this isn’t a problem. However, a shore hookup that’s slightly faulty can result in a ground connection which carries a voltage. This small voltage won’t cause a detectable problem in itself, but it can be enough to bypass the galvanic isolator, eliminating the corrosion protection that it provides. An isolation transformer doesn’t have this weakness.
Isolation transformers also perform other functions besides protection from galvanic corrosion. An isolation transformer is able to accommodate a wide range of input voltages, making them popular with people who travel the world in their boats and connect to onshore hookups with differing voltages.
Besides the higher cost, the other main drawback of an isolation transformer is its significant size and weight.
Which one is right for me?
In short, a galvanic isolator is a relatively cheap and simple device that will protect your boat from galvanic corrosion under most circumstances. However, it does nothing else and can fail or be bypassed, requiring it to be regularly checked, and replaced if necessary.
A galvanic isolator will not fail and won’t need replacing, and in addition it allows you to connect to almost any onshore hookup in the world.
Cost, resilience, and flexibility should determine whether you choose either a galvanic isolator or an isolation transformer for your boat.
We also sell isolation transformers in our shop; check them out here.
The Sterling Galvanic isolator – over-engineered for a very high level of safety
The new Pro Save W offers all the above protection, but in a waterproof plastic package with stainless steel hardware. Further safety comes from an induction fan cooling system, which only operates when the unit is in a major fault condition. This ensures that in full fault condition the product does not exceed 90°C.
The Sterling galvanic isolator 130A also incorporates two LED warning lights, for easy fault communication. The two warning lights indicate the following:
- Breakthrough fault, i.e. the earth voltage has exceeded the ability of the device to protect the system. This can only happen very rarely under exceptional circumstances.
- Total failure due to massive short circuit way beyond the products ability to protect. This would mean that the product has failed and the boat and personnel are in danger.
If your boat and the shore power systems have appropriate safety devices (fuses and trips), it not possible to destroy this product under any fault condition. Total failure can only occur with another underlying event, or an incorrectly rated product on the circuit. The over engineered aspect of this product cannot be overstated.
This product complies to European standard EN ISO13297, but isn’t suitable on boats requiring a UL certificate or ABYC standard.
Looking for a differently sized galvanic isolator?
Take a look at our other options here ⚡
Products that give back
We are members of 1% for the Planet. This means that for every product purchased from Nohma, we will give 1% of the total cost to The Honnold Foundation, to provide solar power to underprivileged communities. If you want your electrical system to have more of a positive impact, purchasing your components from us at Nohma will mean you can give back as well as powering your off-grid system.
Product SKU: ZSW110
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