The wire gauge selected depends on the expected load. A horn that uses 10A would require a much larger gauge wire than an LED masthead lamp. The link below can be used to determine voltage drop. Don’t forget to double the wire length because you have both power and return lines. You might budget a 1/4 v drop as being acceptable. There is no hard limit for this. If your wire is significantly larger than you need you are wasting your money. If its too small, you waste power.

http://www.stealth316.com/2-wire-resistance.htm

Don’t forget to lace in a steel wire with your harness. You don’t want your harness to support its own weight. Over time, the wire will stretch and cause a failure. Attach the steel wire at the masthead so it takes the weight.

Pre-tinned wire is preferable to untinned. Tinning gives the wire some resistance to corrosion. Most wire sold in marine stores is pre-tinned whereas the stuff sold in homegoods stores is usually not.

I assume that your terminal block question is related to connecting all the grounds together at the base of the mast. You want to avoid ground-loops. Here’s an explanation.
http://en.wikipedia.org/wiki/Ground_loop_%28electricity%29

Rich

Post generated from Pearson424 Forum using Mail2Forum

Steel wire. Very smart. Is a ground loop really a concern with lights and other non-musical loads? Don’t they all just lead to the negativ

Adam Silverstein
-iPhone

On Dec 6, 2010, at 12:55 PM, wrote:

Adam,
A ground loop within the mast is of no concern since the wires are laced
together and shielded. A problem might arise if there is a ground loop from
your breaker panel to the base of the mast as might occur if some wires are
fed through different harnesses on the way to the mast. This might generate
a small magnetic field and cause compass errors, though I’d frankly be
surprised if you could measure any deflection. Of greater concern is
electrical noise that might get generated and show up as noise on your
electronic equipment. This might happen if you operate a strobe light or
horn. The horn in particular could cause problems in anything from your
depthsounder to your autopilot since it consumes a lot of current and is
electrically noisy.

Ground loops are hard to avoid on a boat since much of the equipment gets
grounded together through interface cables or chassis grounds. Some
equipment like GPS provide optical isolation in the interface for this
reason, but much of the stuff is not as robust. I suggest avoiding ground
loops where possible. Unless there is some reason to tie grounds together
at the base of your mast you are better off leaving them isolated.

Rich

I found no great way to support the wires wen I did my rewire. The original
wiring was primary wire (individual wires), tied in a knot with a glob of
sealant where it exited the mast. The knot provided wire support. I went
with Blue Sea cable clams to support and protect the wire where it exited
the mast. I then P-clipped the wires on the outside of the mast. I was
refinishing my spars at the same time and if I had t to do over I would have
cut the masthead off and put in a kellum to support the wires from the
masthead.

Example of before : http://www.flickr.com/photos/deepplaya/4617533475/
After: http://www.flickr.com/photos/deepplaya/4747421038/

I’m sure it’s going to last long enough till the next electronics upgrade
will be needed.

-p

—
s/v Deep Playa | Pearson 424 Hull #152 | http://www.DeepPlaya.com

On Tue, Dec 7, 2010 at 7:24 PM, Rich Carter <> wrote:

What is a kellum?…. This is a kellum:
http://cgi.ebay.com/Hubbell-Kellems-Grip-07401010-NPT-1-2-500-625-dia_W0QQitemZ260652545766QQcategoryZ26213QQcmdZViewItem

On 12/7/2010 8:44 PM, Patrick “Peaboy” Walters wrote:

I knew they existed but never knew the name of the part.

Thanks!

Bob

On Wed, Dec 8, 2010 at 9:25 AM, Pete Dubler <> wrote:

Me either.

On 12/8/2010 8:36 AM, Robert Fine wrote:

ABYC specifies that safety equipment which includes navigational lighting shall have no more than a 3% voltage drop and provides appropriate wire sizing based on load and distance.

DO NOT use a common ground. You are asking for issues. It is so simple to run a pair of wires to each lighting system. The savings in wire will be far outweighed by the costs associated with troubleshooting a faulty ground issue. Also, don’t use the mast as the ground, bad juju or use the vessel bonding system.

The other reason not to share a ground is the cool new tri-colors that are on the market. A mast wired for an anchor light, can get a tri-color LED and use the existing wiring as long as it has a dedicated ground. It has a polarity reversal switch that activates it between anchor and nav light.

Put a quality terminal strip, sized for all your terminations in a nice water tight J-box and affix it to a sole support near the mast and you’ll be a happy camper for years to come.

Chuck