T&T: Shore Power and Electricity Concepts (LONG POST - was"Power Cords")

[Ken Bloomfield]

Jim,
It is a bit hard to be definative without looking at your cables and 
splitter, but I suspect what you are running into is as follows:

(a) There are two types of "50A" cables out there, with respective 
connectors.  These are 50A @ 125 VAC, and 50A @ 125/250 VAC.

(b) In the first case, these are 3 wire cables, each with neutral, hot, and 
ground wires that carry 125 VAC with 50 ampere current capability.  A lot of 
the older Bluewater boats in our marina were originally equipped this way.

(c) In the second (now more common) case, the cable has four wires 
internally, and they are neutral, hot #1 aka L1, hot #2 aka L2, and ground. 
Each of the hot wires is capable of carrying 50 amperes and the AC waveform 
relationship is such that the voltage differential between them yields a 
potential difference of 250 VAC.

If you have a splitter, I suspect that if you examine it carefully, you will 
find that it is rated (at the shorepower socket end) as 125/250 VAC at 50A 
and has the four wires internally.  It is likely wired such that on the 
outlet ends that mate with your shorepower cords it has the 3 wire outlet 
sockets that are rated 125 VAC at 50A and I further suspect that if you 
examine the connectors on the cables closely that you will see that they are 
rated 125 VAC at 50A as well.  If my suspicions are correct, then you will 
in fact have 50A on each leg, since the HOT#1 in the four-wire splitter is 
carried on on one of your three-wire cables and the HOT#2 in the splitter is 
carried on the other three-wire cable.

It is always interesting to watch the owners of the 125 VAC/50A cord sets 
trying to find a shorepower socket to fit into.  As someone else posted in 
the last few days, I hate the term "a 50 amp cable" since either of these 
cases could apply.  That poster suggested something like "a 50A dual cable" 
or some such nomenclature, and I wholeheartedly agree.  I am sure your prior 
owner ran into this scarcity of 125 VAC/50A shore-sockets and purchased or 
had made up the splitter you have.

Hope this is of some help and potentially understandable.

Ken.

Ken Bloomfield
MTOA# 2062
AGLCA# 3529
M/V Tellico Lady, 50' Marine Trader-Walkaround
Maryville, TN


> All
> Sorry to add to this already confusing (at least to me) subject but I have 
> a
> situation that I have received at least a dozen different answers to and 
> I'm
> not sure which, if any, is correct.
>
> When I purchased Lark it came with two 50A cables and a 50A splitter that
> hooked to a 50A shore power source.  Each of the 50A cables attach to a
> separate receptacle on the boat.  I have been told the following...
>
> 1.  Due to the splitter I have 50A on each leg
> 2.  Due to the splitter I only have 25A on each leg and would be better 
> off
> buying 2 30A cables so I would have 30A on each leg
> 3.  I could eliminate the splitter and go with one 50A cable and still 
> have
> 50A as both legs share one incoming source (now I am really confused at 
> this
> point)
>
> Hopefully I have supplied sufficient background to receive an answer that 
> is
> correct and that I could understand.
>
>   Thanks for any assistance
>
> Jim Boyd
> Lark