At some point in your cruise planning, you have likely heard that surge protectors are not allowed on cruise ships. So, while you will benefit from having a travel power strip in your cabin, you must take care to select one that does not have surge protection.
Wondering why “no surge protector on cruise ship” is a rule? It’s a matter of shipboard safety. Because of the differences in electricity configuration between land and sea, surge protectors carry an increased fire risk. And, fire on a ship at sea can be particularly perilous!
Keep reading to learn more about why all cruise lines have some version of this rule, and why you should take it seriously.
Why Surge Protectors Are Banned From Cruise Ships
Here is the short answer: The electrical circuits in a house and a cruise ship are very different.
Surge protectors are not allowed on cruise ships because they increase fire risk. The reason this danger exists is that a normal surge protector only breaks the circuit on the “live” electrical wire, whereas both the “live” and “neutral” wires carry current on a cruise ship.
The Electrical Circuit In A House
This is the high-level basic version of how electricity generally works.
We are all familiar with electrical outlets – the items on the wall or floor that allow electrical devices to connect to the electrical grid and receive power. The two sides of an electrical outlet essentially form parts of a loop, and when you plug a device into the outlet, it completes the loop.
Of the slots in an outlet, one will be “hot,” and one will be “neutral.” If there is a third slot, it will be for “grounding.” Thus, for either two-prong or three-prong outlets – only one wire will be hot.
How Electricity Flows in a Circuit
In the outlets in your home, power flows from hot to neutral. The device you plug into an outlet completes the circuit between the hot slot and the neutral slot. Electricity flows through the device and powers whatever the intended operation should be.
A surge protector is designed to interrupt the flow of electricity when it detects an excessive charge that may overwhelm the system.
The live wire delivers 120V (North America), and the neutral wire completes the circuit. The ground circuit is connected to the main breaker panel.
Only one prong out of the three carries a live current.
The typical surge protection device made for home use will interrupt only the hot conductor when a surge occurs.
The Electrical System On A Cruise Ship
A ship’s wiring is different.
Cruise ships (and other large ships) use an UNGROUNDED system to work around this.
Instead of only one prong being live, cruise both the (live and neutral on land) wires.
The live wire carries +60 volts, and the other conducts -60 volts. The current is shaped in different phases (unphased), so the voltage potential is always 120v.
Both prongs carry a live current, and unlike a land-based circuit where only the live prong would give you a shock, both prongs can shock you on a cruise ship.
The outlets are three prongs, but the ship uses a “floating” ground, where the wiring ground is connected but not really “grounded” to the earth.
Why Surge Protectors Create Problems?
Because typical surge protectors only disrupt one of the live currents, in a ship scenario, the second current continues to run. This can create an imbalance of voltage between various power conductors supplying power throughout the ship, which can cause overheating and eventually fires.
Two Scenarios Demonstrate The Danger Of Surge Protectors
The following scenarios demonstrate the danger a surge protector poses to a cruise ship.
Without A Surge Protector
Assume an electrical consumer, such as a toaster or light, developed a loose wire which touched the appliance’s metal cover.
Without a surge protector, a faulty device would ground to the middle wire, which connects to the hull (connections inside the toaster run to that central bottom wire), and the hull will conduct it and safely dissipate the current.
The electrical crew members would notice the current disruption and search out the device causing the problem.
With A Surge Protector
Assume the same electrical appliance is connected to the ship’s electrical source via a surge-protected plug.
The surge protector would register the problem and immediately trip and disconnect the live wire.
Unfortunately, on a cruise ship, because both (the live and “neutral”) wires carry voltage, and so the surge protector would only be disabling half of the circuit with the “neutral” side of the circuit still carrying 60 Volts.
The surge protector would essentially have created a new circuit with the current from the “neutral” wire joining the appliance metal cover, through the ground wire, into the hull,
60 Volts would now travel through the appliance and into the hull.
Surge Protectors are designed to break a circuit for limited duration power spikes.
If the power spike lasts for a long time (as would happen with one circuit still producing power through the “neutral” wire), the remaining circuit will melt and possibly start a fire.
Why No Surge Protector On Cruise Ship: The US Coast Guard 2013 Warning
The notice, which was issued to vessel owners, advised that following the completion of two separate fires on container vessels, they concluded that the immediate cause was surge protector devices that failed.
A marine casualty investigation of two separate stateroom fires onboard a US-flagged container ship attributed the sources of the fires to the use of surge protective devices plugged into a lighting circuit.
The US Coast Guard concluded that even though the live circuit had tripped, current continued to be supplied through the “neutral” circuit and shorted the device’s ground wire to the vessel’s structure.
The Coast Guard advised that surge protector devices used on cruise ships must be able to break both power conductors.
While surge protectors increase safety on land, they can increase the danger of fire on a cruise ship. You can readily find power strips and outlet expanders without the problematic feature, and you should take steps to do so. Stay safe!