New harness wiring - inital

[tac]

GregH:

Good (and inexpensive) solution, well executed.

[joe_db]

FYI, I have been using a relay to start the engine for ages. This was not for spark-proofing, more for reliability. The starter button is a ways from the engine and subject to water. There is no real practical way on my 1973 boat to make a totally sealed instrument panel. This solenoid is from Amazon and intended for the raise and lower controls of Mercruiser I/Os.

[Ram41662]

Okay, as many of you know, my little project, a 1974 Newport 27, includes a complete rewiring. Some of the things I'm dealing with are the same things I've seen mentioned in this thread, such as:

• The fuse bank/power distribution center is right over the fuel tank in an open GRP cabinet.
  
• Non-insulated/non-sealed fittings EVERYWHERE, even on top of the fuel tank and in the bilge.
  
• Non-explosion proof switches close to the fuel tank.
  
• Battery bank next to fuel tank.

And the list goes on. Did I mention the liberal use of wire nuts down in the bilge area as well? Yeh, it's a mess.

All that being said, since I can't see a way to practically seal away my wiring from my main source of explosive gases, the fuel tank, I can address the concern of vapor ignition a few ways. Most are cost prohibitive. That leaves me with my preferred method I've used for years when designing paint kitchens and even containment on bridge and tank projects .

In my opinion, the most reasonable way is to employ several "Intrinsically Safe" design elements to greatly reduce or eliminate the chance of vapor ignition.

So, what are those design elements? Here's my initial list:

1. When reasonable, reroute wiring away from vapor sources and/or low lying areas where vapor collect. If possible, no wires below the sole or in the bilge. That's actually easier than I thought since I'm putting in a new headliner.
   
2. All terminations are to be sealed, both at wire contact and terminal contact. Using proper crimp fittings with heat-shrink/sealing compound addresses the wiring end, a liberal application of OxGard on the terminal helps with the other part.
   
3. Slightly oversize wire to reduce resistance, thereby reducing heat buildup. This one cost a little extra, but I've never had any problems when I do this. The chart calls for 16GA, go with 14GA. It's not hard to do.
   
4. Add other sources and devices to increase the ventilation. You need a combustible gas, at the right concentration, in the presence of oxygen and an ignition source to get that "BOOM!" we all wish to avoid. To that end, adding a small vent fan at the top of the fuse box/ power distribution center that draws in outside air and comes on when the main power is turned on is an example of what I mean. That throws the concentration out of whack, making ignition is less likely. We already do that with out bilge ventilation now.

I have more, but those are the big ones. So, now that I've opened myself up to comments, what do you guys feel is wrong with this plan?

Rick

[ndutton]

Sounds like a decent plan but a couple points of accuracy:

1. "Non-explosion proof switches close to the fuel tank" Please, ignition proof. There's a difference.
2. "When reasonable, reroute wiring away from vapor sources and/or low lying areas where vapor collect" Nothing wrong with that but the concern for the USCG and ABYC is components that produce a spark normally like motors, switches, alternators, starters, relays if any, etc. Wires running through an engine or fuel tank space are not considered spark producing.

[joe_db]

Okay, as many of you know, my little project, a 1974 Newport 27, includes a complete rewiring. Some of the things I'm dealing with are the same things I've seen mentioned in this thread, such as:

• The fuse bank/power distribution center is right over the fuel tank in an open GRP cabinet.
  
• Non-insulated/non-sealed fittings EVERYWHERE, even on top of the fuel tank and in the bilge.
  
• Non-explosion proof switches close to the fuel tank.
  
• Battery bank next to fuel tank.

And the list goes on. Did I mention the liberal use of wire nuts down in the bilge area as well? Yeh, it's a mess.

All that being said, since I can't see a way to practically seal away my wiring from my main source of explosive gases, the fuel tank, I can address the concern of vapor ignition a few ways. Most are cost prohibitive. That leaves me with my preferred method I've used for years when designing paint kitchens and even containment on bridge and tank projects .

In my opinion, the most reasonable way is to employ several "Intrinsically Safe" design elements to greatly reduce or eliminate the chance of vapor ignition.

So, what are those design elements? Here's my initial list:

1. When reasonable, reroute wiring away from vapor sources and/or low lying areas where vapor collect. If possible, no wires below the sole or in the bilge. That's actually easier than I thought since I'm putting in a new headliner.
   
2. All terminations are to be sealed, both at wire contact and terminal contact. Using proper crimp fittings with heat-shrink/sealing compound addresses the wiring end, a liberal application of OxGard on the terminal helps with the other part.
   
3. Slightly oversize wire to reduce resistance, thereby reducing heat buildup. This one cost a little extra, but I've never had any problems when I do this. The chart calls for 16GA, go with 14GA. It's not hard to do.
   
4. Add other sources and devices to increase the ventilation. You need a combustible gas, at the right concentration, in the presence of oxygen and an ignition source to get that "BOOM!" we all wish to avoid. To that end, adding a small vent fan at the top of the fuse box/ power distribution center that draws in outside air and comes on when the main power is turned on is an example of what I mean. That throws the concentration out of whack, making ignition is less likely. We already do that with out bilge ventilation now.

I have more, but those are the big ones. So, now that I've opened myself up to comments, what do you guys feel is wrong with this plan?

Rick

I did some thinking about all the motions required to work on fuel system components when redoing some wiring and plumbing. There are no connections or terminals anyplace near the fuel filter area except some grounds that are exposed in any way. I wanted to make sure working on the fuel filter, fuel pumps, and/or carb presented no chance of hitting something with a wrench that could spark.

[Van_Isle]

Don't forget to also ventilate batteries as well as possible, especially flooded lead-acid. Proper battery boxes with vent hoses leading outside.

[GregH]

Lookee what finally showed up today!

Now I can get the project done and installed

[joe_db]

FYI:
I have been using these waterproof (more or less) boxes and cable glands to good effect on my rewiring project. They are pretty cheap from Amazon.

[marthur]

Post a link or model number!

[ndutton]

I would toss a boot on the toggle switch for the final seal. It’s the only spark producer in the box. Fingers crossed that the toggle cover works with a boot.

[joe_db]

Post a link or model number!

https://www.amazon.com/gp/product/B0159M18EA/ref=ox_sc_act_title_1?smid=A1THAZDOWP300U&psc=1

https://www.amazon.com/Glands-Plastic-Waterproof-Connectors-Adjustable/dp/B077D8MP53/ref=sr_1_2_sspa?s=hi&ie=UTF8&qid=1520461654&sr=1-2-spons&keywords=cable+glands&psc=1

And here is the best way to drill holes in those boxes:

https://www.amazon.com/gp/product/B07422XKQ4/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1

[joe_db]

I would toss a boot on the toggle switch for the final seal. It’s the only spark producer in the box. Fingers crossed that the toggle cover works with a boot.

That is connecting two data inputs to inhibit the AIS. No where near enough current to spark on that one Good advice for some other ones though.

[ndutton]

All I saw was a switch . . . .

[GregH]

Wire harness done and installed. Will tidy the wires up next weekend. The gauge panel sits more proud than the original alum plate so will have to build a mahogany frame around the gauge area and also work in some sort of removeable/flip-up plexi panel.

And yes the switches need labels still. The left most is the blower, center is the ign on, and the right hand momentary switch is to start the engine. Next weekend will be seeing if I cannot get the engine to start !

So far, I know the blower works, the volt gauge reads 12+ V, the fuel gauge works, and there's 12+ V at the coil pos.