T&T: Debugging an electrical problem

[Sean Welsh]

Greg Bradley wrote:
> I guess the next step is to pull the stove and check the voltage at the
> back of the stove?
>   
You could certainly do that as a test.  It is possible that a loose or 
marginal connection in the branch circuit wiring to the stove is adding 
to the problem.

Since you report the stove works fine on generator power, I am still 
suspecting a shore-related issue.  So the next thing I would try is to 
measure the voltage as you just did, but with the stove turned on.  
Stoves draw a lot of current, and an excessively long (or undersized) 
power run from the dock main to the shore pedestal could be causing a 
significant voltage drop.  This will be exacerbated by the length of 
your shore cord plus however much run exists from your shore inlet to 
your main breaker panel.

I've disassembled 50-amp shore pedestals and found them wired with #8 
(50-amp service requires a minimum of #6), and I've also seen them as 
much as 300' from the supplying panelboard (which really should dictate 
using one larger gauge, #4).

Measuring at both the shore inlet and at the stove itself will help 
narrow down where the excess drop may be occurring, if that turns out to 
be the issue.  Measuring at the dock while the power is connected may be 
a bit tricky.  If you have an older style cord, the boot over the 
connector can be slid back, and you can measure by touching your probes 
to the set screws that hold the wires into the plug (and once you have 
the boot back, but with the plug disconnected, is a great time to check 
to make sure these set screws are all still tight.)  More modern cords 
with one-piece molded ends won't let you do this, so you'll need to 
either open the pedestal, or borrow an older style cord.

FWIW, we bought ourselves an inexpensive induction hob (burner), which 
runs on a mere 15-amp circuit at 120 volts.  This lets us cook on 
virtually any type of shore connection available (or even off the 
inverter on battery power).  When we don't need it, it lives in the 
cabinet with our pots.  Induction is a much more efficient electric 
technology than radiant, as well as safer (it's hard to burn yourself on 
an induction hob).  The downside is that induction only works with 
ferrous pots -- we tossed all our quality aluminum cookware and replaced 
it will All-Clad (one of the few quality brands of actually 
ferro-magnetic cookware available in the US).  Take a magnet with you to 
the store -- if a pot does not attract it, it won't cook on induction.  
Our hob is a "Mr. Induction" by Sunpentown, widely available on the 
internet for ~$120, and we've seen them in, I think, Target as well.

HTH.

-Sean
http://OurOdyssey.BlogSpot.com