Connecting 120V grounding to DC negative

[mikeporterinmd]

[flapbreaker]

Mike,

What you say makes sense. However I'm confused about the need for a power chord that's rated for 30 amps but has a 15amp plug to fit the 15amp side of the adapter. I seriously doubt I'll find it. This makes me believe that there isn't 30amps coming from the 15amp side of the adapter. I have an email into marinco to answer this quesiton. I'll report back when I hear anything.

[mikeporterinmd]

Depends on what you are doing. I just bought a 15 Amp -> 30 amp
converter so I can plug in my boat while at home. This is safe
because the outlet at the garage, the extension cord and the connector
are all rated at 15 (20) amps and the outlet on the garage has a
20 amp breaker.

But, using a converter to convert a 30 amp dock connection down to
15/20 amp isn't safe unless you change the breaker at the dock
to 20 amps.

Basically, extension cords don't belong in the marina.

Of course, you can have a private dock with 20 amp service, or
perhaps your marina does have 20 amp available.

Mike

[mikeporterinmd]

By the way, the adapter pic you show is for plugging a 30 amp shore
cord into a 20 amp outlet. This is safe. I have one. I decided to
get the opposite and run an extension cord at home because I don't
want the shore cord sitting outside all winter.

Mike

[flapbreaker]

Mike,

I had the wrong 30 amp adapter pictured. I've updated my original post. Here is what it looks like now. Notice that my CGFI/breaker box has a 15 amp cord and I was planning on running it to the power inlet. Then the 15amp side of the adapter plugs into the CGFI. If I understand correctly the cable from the CGFI is the unsafe part since it's only a 15 amp chord? Even though marinco makes an adapter to downgrade (maybe it doesn't do what I think it does?) the 30 amps to 15 amps? Sorry for all the pesky questions just want to make sure we understand each other.



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[mikeporterinmd]

[thataway]

This is probably an appropiate place to mention a common problem with boat wiring systems. Mike mentioned a fire--and I don't have any idea what caused that fire. But one of the most common reasons for 110 V over heating/fires is at the plug to the boat (female cord/boat recessed male). The boat fitting often gets some salt/corrosion and increases resistance. Often the shower power is not turned off properly before this plug is disconnected--and arcing occurs. With carbon formation, detiorration of these plugs, heat builds up--and the plug plastic softens and eventually causes a short--or enough heat build up to cause a fire. Often these plugs don't have the ring which tightly holds the plug to the boat fitting, or the ring is not tight, and the fitting works, increasing the potential of arcing.

Always turn off circuits in the boat, and on the dock breaker before unplugging the cord at the boat (and at the plug). Inspect both the male and female fittings regularly to be sure that there is no carbon build up, sign of increased corrosion and resistance, or melting of the plastic.

[mikeporterinmd]

This is exactly the fault that the surveyor found on our last boat. The inlet
needed to replaced.

Mike

[Sea Wolf]

I've had exactly that problem with one of my boats! Noticed the amperage and voltage meters bouncing around (surging) and traced it to that connection and a loose threaded lock ring.

Also, be sure you have the plug twisted in the lock position not the release one, or the connection will be shaky.

As a side note, I noted that with 110 volts registered on the electrical panel voltmeter, my upolstery stapler seems to work at 1/4 strength. Back at home with 125 volts, it pumps them babies in like a pneumatic tool! Amazing what the loss of 10-15 volts can do to some voltage sensitive appliances and tools.

Joe.

[mikeporterinmd]

One way to nearly connect the AC to the DC ground to almost get the
shore cord under the skeg and accidently hit the down button. That
was close...

Mike