Should I be using GFCI Outlets for Railway Passenger Cars

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b1miller

b1miller

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Washington
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Electrician/Electrical Administrator/SCADA Engineer
I recently retired from a long career as an 01 Electrician and Electrical Administrator. I am volunteering several days a week at a local tourist railroad and museum. As part of my duties I have designed and am installing a new and safer electrical system in several 100+ year old railway passenger coaches. Each car now has a 480-120/240V 5 kva single phase transformer feeding a 120/240V breaker panel for lighting and receptacles. I am know thinking that it might be a good safety idea to upgrade the existing receptacles to a GFCI receptacle. All new wiring is enclosed in flexible conduit or LFMC with a separate grounding conductor. Each lighting panel has the neutral bonded to whatever steel structure exists in the railcar. The 480V power system has all been upgraded with new conduit and wiring including self ejecting plugs and connectors between cars.

Trust me-the existing old 32VDC wiring was a non starter and it has all been removed. So from strictly from a passenger and train crew aspect would GFCI protected outlets be a good idea?
 
probably a good idea.

If it is still being used as rolling stock though the NEC would not apply. I don't know that the code would require the use of GFCIs in this case anyway.

IMO, if it is not rolling stock, what you have created is a series of SDS. The code would require each one of them to have a grounding electrode system and a grounding electrode conductor.

90.2 Scope.
...
(B) Not Covered. This Code does not cover the following:
(1) Installations in ships, watercraft other than floating buildings,
railway rolling stock...
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They are in service as passenger cars. Typical use of outlets are XMAS lighting and small heaters for train crew comfort during fall and winter excursions. I agree NEC does not apply here but am planning on converting receptacles to GFCI as a safety issue.
 
180406-1628 EDT

Use GFCI receptacles. Any I have tested worked.

A GFCI basically works with two wires, hot and neutral. The EGC in the receptacle has no function in the operation of the GFCI. If there is no EGC the device still works. The only thing tested is the difference in current between hot and neutral. If this difference exceeds about 5 mA for more than a short time the device trips.

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b1miller said:
They are in service as passenger cars. Typical use of outlets are XMAS lighting and small heaters for train crew comfort during fall and winter excursions. I agree NEC does not apply here but am planning on converting receptacles to GFCI as a safety issue.
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I can't think of much in the way of downsides to doing so and it might be somewhat safer. Whether it really is safer or not for this type of application is questionable.

I will point out that GFCI receptacles are known for failing regularly and often fail in a way that they are not tripped and won't trip. I think the new ones are self testing and will give some indication if they fail the test, but they still can fail in a non-failsafe way.
 
GFCI's it is. I have some on order for install next week.

I'm old school when it comes to pulling ground wires. I have never trusted raceways as a effective, long term grounding method.
 
gar said:
The EGC in the receptacle has no function in the operation of the GFCI. If there is no EGC the device still works. The only thing tested is the difference in current between hot and neutral. If this difference exceeds about 5 mA for more than a short time the device trips.
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True, but the GFCI does require that the supply neutral be bonded, or accidental contact with the ungrounded conductor creates no unbalancing current.

Plug-in GFCI testers, on the other hand, do require EGCs, because the tester doesn't have access to the grounded conductor to mimic a shock condition.
 
180406-2118 EDT

LarryFine:

If you have a circuit with the neutral unbonded, then what is the 120 V circuit that will cause you to get a shock current greater than say 20 mA via ground and not be an unbalanced current thru the GFCI?

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gar said:
If you have a circuit with the neutral unbonded, then what is the 120 V circuit that will cause you to get a shock current greater than say 20 mA via ground and not be an unbalanced current thru the GFCI?
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Presuming you mean from one circuit conductor through your body to earth, there isn't one. Ignoring capacitance, an ungrounded circuit won't drive any current through your body. If you're fully insulated from earth, a grounded supply won't, either.
 
180408-0813 EDT

LarryFine:

My question was only because your statement seemed to imply that one could get shocked if the neutral was open.

With a modern GFCI receptacle the GFCI will trip if the path from the output neutral terminal to the input neutral terminal is greater than about 5 ohms. Thus, if input power to the GFCI is floating the GFCI will trip.

Normal cable capacitance, except for very long cables, probably is insufficient to get 5 mA at 120 V.

If that open neutral function did not exist, then in the real world there might be noise filters that might produce a sufficiently high conductivity path to provide a greater than 5 mA current.

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