Understanding old marine wiring gronding er, lack of.
Understanding old marine wiring gronding er, lack of.
(OP)
Hello all, this is my first post on the website. I am an electrician up in the fine state of Alaska.
As part of my duties, I assist in the upkeep of four floating bunkhouses that are on steel barges that were built in the 80's or early 90's.
My experience is in residential, commerical, and industrail wiring so I have taken a crash course in to the marine wiring whelm in the last few years. Although I am confident in my understanding on marine wiring, one thing that has been elusive to me is the grounding on these barges.
I have been trying to piece the history. These systems on the barges have been goobered and rehash to fit someones mood and I inherited their mess. Here is what I know and what I think.
I do believe when the barges were origionally built, the electrical system was a paralelled (2, 20kW gensets) ungrouded system. This is indicated to me by the fact the original control panel still has a ground fault detection system (no longer connected) and the electrical panels throughout break the neutral when open. What I believe is through the years as these systems were modified, the distribution system was converted to a grounded system but left the panels as they were so the breakers still open the neutral.
Since the system is a grounded system and the gensets are not paralled anymore, I feel that there is no need to break the neutral any more. I feel that the switched neutral is a relic of the old ungrounded days. I would like to do away with the switch neutral breakers since each neutral takes a space in their small panels and we are running out of spaces to add more.
Without putting anyone on the spot, is there any reason to keep on breaking the neutral on a grounded sustem that is on a steel vessel (barge)? If I do remeber correctly, emergeny electrical systems are ungrounded and require the ground detection systems and stuff. I do not have that requirement with my barges. Any thoughts? any insight would be muchly appreicated. Thanx
As part of my duties, I assist in the upkeep of four floating bunkhouses that are on steel barges that were built in the 80's or early 90's.
My experience is in residential, commerical, and industrail wiring so I have taken a crash course in to the marine wiring whelm in the last few years. Although I am confident in my understanding on marine wiring, one thing that has been elusive to me is the grounding on these barges.
I have been trying to piece the history. These systems on the barges have been goobered and rehash to fit someones mood and I inherited their mess. Here is what I know and what I think.
I do believe when the barges were origionally built, the electrical system was a paralelled (2, 20kW gensets) ungrouded system. This is indicated to me by the fact the original control panel still has a ground fault detection system (no longer connected) and the electrical panels throughout break the neutral when open. What I believe is through the years as these systems were modified, the distribution system was converted to a grounded system but left the panels as they were so the breakers still open the neutral.
Since the system is a grounded system and the gensets are not paralled anymore, I feel that there is no need to break the neutral any more. I feel that the switched neutral is a relic of the old ungrounded days. I would like to do away with the switch neutral breakers since each neutral takes a space in their small panels and we are running out of spaces to add more.
Without putting anyone on the spot, is there any reason to keep on breaking the neutral on a grounded sustem that is on a steel vessel (barge)? If I do remeber correctly, emergeny electrical systems are ungrounded and require the ground detection systems and stuff. I do not have that requirement with my barges. Any thoughts? any insight would be muchly appreicated. Thanx
"Good judgement comes from experience. Experience comes from bad judgement." - unknown





RE: Understanding old marine wiring gronding er, lack of.
RE: Understanding old marine wiring gronding er, lack of.
"Good judgement comes from experience. Experience comes from bad judgement." - unknown
RE: Understanding old marine wiring gronding er, lack of.
If the neutral and hot get swapped the circuit will still be hot with only a standard breaker opening the black lead.
RE: Understanding old marine wiring gronding er, lack of.
"Good judgement comes from experience. Experience comes from bad judgement." - unknown
RE: Understanding old marine wiring gronding er, lack of.
In other words, think about when the breaker is opened manually (for example).
Combined with un-trustworthy grounding and external power, it makes sense to open the 'neutral'.
RE: Understanding old marine wiring gronding er, lack of.
11.29 Overcurrent protection of conductors
Except as otherwise recommended in 7.8 and 18.3 (steering systems), overcurrent protection by fuses or circuit breakers should be provided for all ungrounded conductors. Fuses should not, and circuit breaker overcurrent trips need not, be provided for the neutral conductor of a three-wire grounded system, but provision should be made for feeder disconnect including the neutral.
The purpose of overcurrent protection for conductors is to open the electric circuit if the current reaches a value that will cause an excessive or dangerous temperature in the conductor or conductor insulation. A grounded conductor is protected from overcurrent if a protective device of a suitable rating or setting is in each ungrounded conductor of the same circuit. For ac systems over 600 V, fuses should not be used for overcurrent protection.
7.8.3 Feeder cables—overload and short-circuit protection For each distribution circuit, a circuit breaker with a pole for each conductor should be provided, except for three phase grounded systems where the grounded conductor need not be opened. Circuit breakers of the power or molded-case type should be used and are preferred. Fused switches may be used up to 200 A. Overcurrent protection should be provided for all ungrounded conductors. Fuses should not be, and circuit breaker overload trips need not be, provided for the neutral conductor of a three-wire dc grounded system.
RE: Understanding old marine wiring gronding er, lack of.
See the 2nd page.
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RE: Understanding old marine wiring gronding er, lack of.
"Good judgement comes from experience. Experience comes from bad judgement." - unknown