Well... last night was the end of the 7 hour Basic Marine Wiring class (spread over two evenings) hosted by Port Of Edmonds and presented by Dick Troberg.
It was an excellent class too be sure. Full of great information and interesting anecdotal stories given by Dick along the way.
Here are a few one liners taken from Dick's presentations...
1. The cost of the wiring in a new boat is around 1% of the boat's price!
2. 60% of boat incidences/accidents are caused by electrical failures.
3. 90% of electrical problems are caused by corrosion.
4. Of the many things to avoid, one was to avoid using automotive fuses with aluminum blades (our Ranger Tugs use these!!!)
5. Solid wires should NEVER be used.
6. 60% of all West Marine batteries sold are returned during their warranty period!!!!!! There are are lot of "battery killers" out there.
7. A well cared for battery should last 14 years -- well beyond the warranty period.
8. It's possible to make an electrical connection that will last for 30 years (under water).
9. A Digital Multimeter should be part of a boater's toolkit.
10. A small can of KOPR-SHIELD should be part of the toolkit - see
http://www.tnb.com/ps/con/msds.cgi?action=tiff2pdf&f=/shared/msds/msds-0025-tb2.tif and
http://www.google.com/search?client...,cf.osb&fp=15c021a1e7fc6c32&biw=1059&bih=1076
One of the subjects covered was "Loss of Protection Current through Shore Ground". Galvanic isolators can prevent loss of zinc current through the show ground. Using an Amp Clamp it's quite easy to determine any unwanted stray current. This is done simply by using the Amp Clamp on the shore power line. If current flowing into the boat is same as current flowing out then the Amp Clamp reading should be zero (0.00). If it's not then splitting the shore line into its three (3) wires allows the stray current to be detected. Given this, today I used a free service offered by my Port Of Edmonds to perform the Amp Clamp test for my boat which is moored at this marina.
The Amp Clamp used on my shore line with breaker on was displaying 0.02 to 0.03 amps. Hmmmm, as it should be zero, just what was causing this... and the answer is far from easy.
Inserting a line splitter between the show power connection and my shore line allowed the Amp Clamp to be used on each of the three wires; Black, White and Green. With the Dockside shore power breaker OFF the Black=0.00, the White=0.00 and the Green=0.03. Withe the Dockside shore power breaker ON the Black=2.5, the White=2.5 and the Green=0.03. The 2.5 slowly decreased.
I had the Frig, a humidifier and battery charger active on the boat so that accounted for the 2.5 amps and the decreasing amperage as the battery charger and/or frig quite likely cycle.
We took the Amp Clamp to shore power lines for several boats on either side of my slip and one across from me. Most read 0.00 but one immediately next to me was treading 0.02.
Well, no good answer was apparent for the Green(ground) 0.02 to 0.03 amps for my boat, BUT the very low amperage of 3/100 of an amp really was not too much to worry about (at least this is what I've been told).
I'm also told that some boaters actually disconnect the shore power ground line at the boat to eliminate this current flow... dangerous IMO.
We had several hands-on exercises which were fun; wire butt joining, shrink wrapping, shrink wrapped labels, terminal installation and using Digital Multimeter to create a 9v circuit to lit up a LED. Dick supplied all the materials and tools for the job.
Port Of Edmonds & Dick Troberg will be offering this class again in the Feb/Mar 2012 timeframe along with Dick's Corrosion class.
This was an excellent use of 7 hours.
🙂
Some pics below...
Shrink wrapped label
Shrink wrapped butt joint
Glue inside shrink tubing
Terminal connector
Misc notes etc
Amp Clamp
Shore line splitter
With the Amp Clamp around the complete yellow shore line the reading should be 0.00. For my Ground line it showed 0.03 amps for my boat -- so where was this coming from ?
My boat's Battery charger+Frig+Dehumidifier current draw
