Wednesday, September 9, 2015

Casualty Power

Many years ago, I made a reference to electricians rigging casualty power. I really don't have much to say about it, but here goes.

Ships had lots of casualty power risers and bulkhead pass-throughs. In my day, they looked like this:

This is a bulkhead pass-through:

And this is a riser, which connects different decks:

On the distribution route for casualty power, there was a terminal at either end of a given compartment. Cables would be broken out and strung between the terminals.

The principle was simple: Each cable had three terminal ends to it, because the lines were transmitting 440 volt three-phase power. You connected A to A, B to B, and C to C, and then tightened the cables' connection into the terminals with those little wrenches. You would run the wires from the load to the source, so that you were always connecting and disconnecting dead wires. The ends of the cables had o-rings or twine wrapped around them so you could identify them in the dark: One loop for A and so on. Only electricians could do anything with casualty power lines, because of the hazards of using them.

Each ship was supposed to have a "Casualty Power Bill" to set forth the procedure for using the casualty power system. I suspect that was one bill that was drawn up during pre-commissioning, validated at the first refresher-training session, and then never touched.

It took many decades (and long after I was out), for NavSea to figure out that color-coding the damn things might be a better idea, as connecting the A wire to the B terminal was a bad thing:

Supposedly they've since tried to sailor-proof them with connectors that can only be installed one way:

The cables were supposed to be strung from the overhead, in order to keep sailors from tripping over them. A close eye was to be kept on the cables to ensure that they didn't start smoking or burning due to overloading or any defects in the cables.

While the electricians would occasionally drill with rigging and un-rigging the cables, in all of my time, I never once saw them actually energize the things. They were, in essence, a bunch of 440v extension cords that could handle between 100 and 200 amps and nobody, but nobody, really wanted to fuck around with that much live power.


physioprof said...

Sounds fucken dangerous.

Comrade Misfit said...

Sounds fucken dangerous.

Definite "no shit, Ensign" on that!

BadTux said...

440 volts will focking *bite* you. Back when I was apprenticing as an electrician, my boss managed to get his hand too near a 440v power source. It jumped to his hand, ran up his arm to his elbow, then jumped to the electrical box he was working in, burning off all the skin on his arm in the process. And that was with him doing everything *right*, rubber soled shoes, only one hand being used, not leaning against anything, just getting slightly too close to a live 440v power source.

Dr. Hazmat said...

This is really interesting -- thanks for putting this up! I'd seen the casualty power terminals aboard Midway when I visited her in San Diego a few years back, and had a vague inkling what they might be used for, but wasn't entirely sure (and my Google-fu failed completely). Didn't realize they were intended to carry that much power.

Robert said...

We had 1.5kv 400Hz three phase coming into our motor-generator room where the juice was transmogrified into whatever our gear ate. Things caught on fire more than once. Luckily, 'twernt my job to fix it.