Engine-Room Safety and Hazardous Materials

What the rule requires

Electricity in a wet, grounded space

Current kills. Voltage matters only because it drives current, and how much current flows is set by body resistance: dry, intact skin may be 100,000 ohms or more, but wet skin or a cut can drop it to a few hundred ohms, so even low voltages become lethal in the damp, grounded environment of an engine room NEETS Mod. 1 §1-4.

That single fact drives every electrical precaution the oiler is held to:

Treat every circuit as live until proven dead.
De-energize and lock/tag out before working.
Use one hand where the job allows, to keep current out of the chest.
Wear insulated footwear and stand on rubber matting.
Never wear rings or a metal watch.
Use insulated tools and correctly rated fuses.

The tag-out program is not an informal habit; it is administered as a named program within engineering administration alongside the safety program and the 3-M system NAVEDTRA 14104 Ch. 13 — Eoss 1-12.

For the casualty: de-energize the source or free the victim with a non-conductor without touching them directly, then check breathing and pulse and begin CPR or rescue breathing immediately if either is absent, because respiratory arrest from shock is common. Electrical burns are often deep and worse than they appear. Treat the victim for shock — the medical kind — and get medical help .

An oiler is found gripping the frame of an energized 120-volt pump motor and cannot release it. What is your first action?

De-energize the circuit, or free him with a non-conductor without touching him directly. He cannot let go because the current is holding his muscles contracted, and if you grab him bare-handed you become the second casualty. The voltage being "only" 120 is irrelevant — on a wet deck his resistance may be a few hundred ohms .

The general safety rules

Safety must be practiced at all times, no matter how small the job, and a tool that is efficient, essential, time-saving or convenient is also dangerous NAVEDTRA 14256 — Safety and Safety Equipment. Ten general rules are furnished as a guide. Four of them decide questions because they name an action and an addressee:

Inspect tools and equipment for safe condition before starting work.
Advise your supervisor promptly of any unsafe condition or practice.
Operate only the equipment you are authorized to use.
Report any injury immediately to your supervisor.

The remainder: support the local safety program and take an active part in safety meetings; learn the safe way to do the job before you start; think safety and act safety at all times; obey safety rules and regulations, which exist for your protection; wear proper clothing and protective equipment; and conduct yourself properly at all times, horseplay being prohibited.

The safety equipment named for the shop and the engine room is safety shoes, eye protection, helmets, gloves, safety belts and safety straps, and ear protection.

The new hand, and what he must not touch

Before a trainee is assigned any actual duty he is introduced to the engineroom and made familiar with the location of all machinery, equipment, piping and valves. He is instructed in basic safety precautions and specifically warned about the dangers of turning valve wheels or tampering with machinery NAVEDTRA 14075 Ch. 2 — Training Responsibilities ¶1. The rule offered for any new person in the space is short enough to remember on watch: if in doubt, ask questions.

Personnel are started out under the supervision of an experienced throttleman and remain under that supervision until the petty officer in charge of the engineroom is fully satisfied that the trainee is completely qualified for the duty.

Because safety precautions must be strictly observed, all engineroom operational training is rigidly controlled and supervised. On-the-job training is necessary to acquire the actual skills of main engine operation, but the person must not be allowed to learn by trial and error, since errors could be too dangerous and too costly. Safety precautions are taught from the very beginning and emphasized constantly throughout the training program NAVEDTRA 14075 Ch. 2 — Training Responsibilities ¶2.

Doing the work safely

Regular inspection catches many malfunctions before a serious casualty results, and a planned maintenance program prevents major casualties and many operating troubles NAVEDTRA 14075 Ch. 3 — Engine Maintenance. Where a ship's 3-M System includes safety requirement cards, those cards give the guidelines and the periodicity for inspecting selected areas not covered by the regular maintenance schedule — that is their whole purpose, and it is the phrase to look for.

Four general rules apply to overhaul on any engine:

Study the manufacturer's instruction manual and the maintenance pamphlets before attempting any repair work, paying particular attention to tolerance limits and adjustments.
Observe the highest degree of cleanliness in handling engine parts.
Before starting the work, be sure all required tools and the replacements for known defective parts are on hand.
Keep detailed records of repairs — measurements of parts, hours in use, names of new parts installed.

When service requirements interfere with planned maintenance, the routine maintenance is performed as soon as possible after the specified interval has elapsed. Repair jobs must not be allowed to accumulate, because the result is hurried and inadequate work.

Hazardous material topics and where they sit

The hazardous-material material for this rate is distributed rather than gathered in one chapter, and in an open-book sitting the index is the fastest route to it: halocarbon safety sits with refrigeration system maintenance, oil pollution is broken into responsibilities, spill phases and causes of oil spills under pollution control regulations, and noise pollution carries the hearing conservation program NAVEDTRA 14075 Ch. 9 — Battle Casualties ¶2. Ear protection is the item of personal protective equipment that answers to the noise hazard .

Telling it apart

One quantity separates a shock you will remember from a shock that kills you: the amount of current through the body. The old yard saying is that amps kill and volts thrill — correct as far as it goes, but it invites the wrong conclusion that low voltage is harmless. Voltage decides how much current flows through whatever resistance you happen to be offering at that moment, and that resistance is not fixed.

About 1 mA — perceptible. You feel it. Nothing more.
About 10 mA — the muscles at the point of contact freeze, producing the "can't let go" condition. The victim cannot release the conductor by his own effort, which is why the rescuer's problem is the circuit and not the grip NEETS Mod. 1 §1-4.
Roughly 100–200 mA through the chest — ventricular fibrillation and death. Note the path: through the chest. This is why the one-hand rule exists.

And the resistance either side of that:

Dry, intact skin — 100,000 ohms or more.
Wet skin, or skin broken by a cut — down to a few hundred ohms.

A candidate who holds those five numbers can answer any threshold question on this topic and can also reason his way through a scenario question, which the numbers alone will not do.

Working a question

An oiler is found slumped against the controller for a bilge pump, hand on the enclosure, in a space with water on the deck plates. He is not moving.

Identify the hazard before the injury. He is in contact with an enclosure you must assume is energized. Treat every circuit as live until proven dead — the fact that a shipmate is already down is not evidence the circuit has cleared.
Break the current path — that is the first action. De-energize the source. If you cannot reach the breaker or switch, free him with a non-conductor. Do not touch him directly; his body is part of the circuit and the wet deck has already collapsed your own resistance.
Then assess breathing and pulse. Only after the current path is broken. Respiratory arrest is common in electrical shock, so this check is not a formality.
Begin CPR or rescue breathing immediately if either is absent. Immediately, not after summoning help and not after the burn is dressed.
Do not be reassured by the appearance of the burn. Electrical burns are often deep and far worse than the surface suggests.
Treat him for shock and get medical help NEETS Mod. 1 §1-4.
Report the injury immediately to your supervisor NAVEDTRA 14256 — Safety and Safety Equipment.

The step that is graded is step 2, and the distractor that catches people is any option that puts CPR, a call for help, or moving the victim ahead of it.

Where candidates lose the point

Reads the hazard as voltage and calls a low-voltage circuit safe. A 120-volt lighting or pump circuit reads as harmless next to a 450-volt bus, so the candidate picks the answer that puts the danger threshold at high voltage. Body resistance is the limiting factor, and wet skin or a cut takes it to a few hundred ohms, so low voltages become lethal in a damp, grounded space.

Pulls the victim clear first. This is the instinctive answer and it appears in the option list precisely because it is instinctive. Correct sequence: de-energize the source, or free him with a non-conductor without touching him directly.

Confuses the let-go current with the lethal current. Both are muscular effects at first glance. The 10 mA figure freezes the hand at the point of contact; it takes roughly 100–200 mA through the chest to fibrillate the heart.

Treats the trainee's first watch as learn-as-you-go. An answer that has the new hand operating machinery to gain experience looks like sound practical instruction. Operational training in the engineroom is rigidly controlled and supervised, the trainee is not allowed to learn by trial and error, and he is warned specifically against turning valve wheels or tampering with machinery NAVEDTRA 14075 Ch. 2 — Training Responsibilities ¶2.

Corrects the unsafe condition himself, or operates the gear to prove it faulty. The rules give the action away: advise your supervisor promptly of any unsafe condition or practice, and operate only the equipment you are authorized to use NAVEDTRA 14256 — Safety and Safety Equipment.

Starts the overhaul and gathers tools as needed. The rule is that required tools and replacements for known defective parts are available before the work starts, alongside studying the manufacturer's manual first NAVEDTRA 14075 Ch. 3 — Engine Maintenance.

Holds a minor injury until the end of watch. The rule says report any injury immediately.

Check yourself

You are standing on a wet deck plate with a small cut on your right palm, about to check terminals in a 120-volt panel. Why is this more dangerous than the same job with dry hands?

Because body resistance is what limits current, and dry intact skin may be 100,000 ohms or more while wet or broken skin can fall to a few hundred ohms. The same voltage therefore drives far more current, and low voltages become lethal in a damp, grounded space NEETS Mod. 1 §1-4.

Roughly what current through the chest causes ventricular fibrillation and death?

Roughly 100–200 mA. About 1 mA is merely perceptible, and about 10 mA produces the "can't let go" muscular freeze at the point of contact.

Why is the one-hand rule taught for work on energized equipment?

To keep the current path out of the chest. The lethal figure is stated for current through the chest, so keeping the second hand off grounded metal keeps the path from hand to hand across the heart.

An engine-room ventilation fan guard is loose and rattling. It is not your equipment and it is not on your card. What do you do?

Advise your supervisor promptly of the unsafe condition. You are also to operate only the equipment you are authorized to use, so undertaking the repair or running the fan to assess it is not your call NAVEDTRA 14256 — Safety and Safety Equipment.

A trainee on his first day in the space asks whether he should shut a valve he believes is lined up wrong. What is the correct instruction?

He asks first. New personnel are specifically warned about the dangers of turning valve wheels or tampering with machinery, and the standing rule for anyone new in the engineroom is that if in doubt, ask questions NAVEDTRA 14075 Ch. 2 — Training Responsibilities ¶1.

Your ship's 3-M System includes safety requirement cards. What does a safety requirement card cover that the regular maintenance schedule does not?

It provides the guidelines and the periodicity for inspecting selected areas not covered in the regular maintenance schedule NAVEDTRA 14075 Ch. 3 — Engine Maintenance.

Steaming requirements pushed a scheduled maintenance item past its interval, and two other repair jobs are now waiting behind it. What does the manual require?

Perform the routine maintenance as soon as possible after the specified interval has elapsed, and accomplish all necessary corrective measures as soon as possible. Repair jobs are not to be allowed to accumulate, because hurried and inadequate work results.

A shipmate has taken a shock, is conscious, and has a small burn on the fingertips that looks trivial. Is medical help required?

Yes. Electrical burns are often deep and worse than they appear. Treat the victim for shock and get medical help, and report the injury to your supervisor immediately .