Cruise lines are pretty picky regarding guests thwarting cabin electrical systems and pertinent ship policy. In my opinion, justifiably so. #1 reason is due the greatest fear on board vessels--- "FIRE". They have other excellent reasons as well. I.e.:
"Most surge protectors are in the form of power strips, which allow multiple devices to be attached to the same surge protector. Unfortunately this also allows people to attach more devices to a single wall socket than is safe. Attempting to draw more power from the wall than the hardware can handle can cause fires. Please leave your surge protectors, power strips & extension cords at home. Cheap ones are extremely dangerous as are the older models (I'm told by an electrician that we should replace ours every 2 years.) Engineers have very carefully calculated the amount of electricity to run the ship and how many outlets can safely be installed in each stateroom. I do agree that all of the cruise line should do a better job of informing their passengers to the danger of overload. People seem confused and unaware of why the number of outlets are minimum. Trace Atkins' home is a total loss due to a faulty power strip"
Courtesy: Capt. B.J.:
"The electrical systems you find on land are not exactly what you find in the shipboard environment. The difference has to do with grounding. On land we ground to that .... the ground! Or EARTH. And we do that thru wires - we hope, but a little loose current in the foundation is no biggie
On a ship you ground to the sea if you followed the same principle, problem is the ship is steel and if the ship's hull transmits any of that juice to the sea a bad thing happens - actually several. For one - electrolysis - the flow of electrons away from the ship carries molecules of metal. The hull erodes to the point that ships develop weakened hulls and even holes in the props and rudders. Not good things. (ships try to mitigate this which can never be totally eliminated by attaching a sacrificial metal to the hull. One that will carry away more easily then the metal of the hull. These blocks of ZINC are seen even on smaller boats and outboard motors. Zincs are one of those items that are checked and replaced as needed during a dry dock period.) Also if there is a 'short' or a 'ground' on a ship that can cause the walls and floors and everything else to be electically hot - ships are not framed in wood anymore. It is very very important to keep the electric distribution on a ship a closed system. It is different than on land.
So what? Well, most power strips are also surge protectors and the way surge protectors work on land is most of the time not completely friendly to a ship's grounding system. How unfriendly? I have honestly seen a surge protector power strip burst into flames with no warning what so ever. I was involved with some of the first installations of desktop computers on ships for the organization that paid me. We learned this the hard way and eventually there were Navy safety warnings about the dangers of powerstips/surge protectors/and interruptible power supplies on ship's. There were only a limited few models that were approved for shipboard use - UL TESTING HAS LIMITED APPLICATION IN THE SHIP ENVIRONMENT"
"I believe that the reasons for the cruise companies trying to limit the use of these devices on their ships is that they have no control over the quality of the device nor of the physical condition of the devices that people bring on board." For what its worth - extension cords were also strongly frowned upon because of the increased dangers associated with a frayed cord in the marine environment. Cords which were approved for use were regularly inspected and tagged as such ..."