Basic Boat Electrical Questions

[jhance]

I am adding some electrical and want to improve a few things on the boat. Some basic/newbie questions below.

1. Any issues running multiple terminal or junction blocks in one circuit? This if I want to branch off different sets of lights in different directions.
2. Are junction blocks THE preferred method for making a junction between three or more wires?
3. How would you bring two positive wires together and then run a single from there to power source?
4. Good idea to fuse an LED lighting circuit even if connected to circuit breaker?
5. Lighting circuit with multiple runs should go to a fuse or terminal block and then one thicker wire to breaker for one connection at breaker?
6. Terminal block the best way to join two wires of different gauge?

This of course using the proper crimped terminals with proper size wire.

Not used to DC wiring. In AC it's all done with wire nuts and junction boxes!

My very crude circuit attached. Most of that is existing wiring. Adding the LED sections and removing multiple connections at the breaker. Input welcomed if there is a better way.

Thanks in advance.

Jamey

 

[SteveK]

any issues? YES
Imagine the previous owner did what you are suggesting and now you are trying to find out why a light does not work. The breakers are all on, so is it a fuse in the line, or is it a broken connection.
Daisy chain, subject to load limit. all connections at a light or switch.
Terminal blocks should be highly visible usually in the electric fuse/breaker box area.
IMO

 

[Comodave]

I am adding some electrical and want to improve a few things on the boat. Some basic/newbie questions below.

1. Any issues running multiple terminal blocks in one circuit? This if I want to branch off different sets of lights in different directions.
2. Are terminal blocks THE preferred method for making a junction between three or more wires?
3. How would you bring two positive wires together and then run a single from there to power source. Small terminal block?
4. Good idea to fuse an LED lighting circuit even if connected to circuit breaker?
5. Lighting circuit with multiple runs should go to a fuse or terminal block and then one thicker wire to breaker for one connection at breaker?
6. Terminal block the best way to join two wires of different gauge?

Not used to DC wiring. In A.C. it's all done with wire nuts and junction boxes!

Thanks in advance.

Jamey

I have never seen the need for multiple terminal blocks in one circuit but I guess it is ok if you don’t overload the circuit.

Terminal blocks are a good way to connect 3 or more wires but it is ok per ABYC to put up to 4 wires on one connection.

You could use a terminal block or a power post for up to 4 wires.

Always a good idea to fuse a circuit. Circuit breakers are there to protect the wiring.

In my engine room I have multiple LED light fixtures that go to a terminal block and one larger wire feeds the terminal block. It is labeled “Positive LED”.

I use small terminal blocks to join wires of 2 sizes.

 

[STB]

1. There is contact resistance any at each connection, including between each wire and the terminator and between the terminator and the block. This starts out relatively insignificant, but with corrosion it can go up. Terminal blocks normally leave the energized and/or grounded terminals exposed. This may not be what you want.

2. In my mind, one is far better off with properly done crimp-on heat shrink butt connectors. They are cheaper and seal the wiring.

3. You are allowed to put two wires into a single ring butt connector, ring terminal, spade terminal, etc. But, if you do, the two wires still need to be a good fit for the terminal and still needs to pass the pull test. Sometimes when I've done this, I've used a step up barrel connector that has a larger diameter on one side than the other. This way, each of the single wire and double wire can get a good bite. You can also, as you suggest, use a terminal block and terminate the wires with ring terminals. You can also look at Blue Sea Systems Euro-style blocks, which will save you the connectors.

4. The circuit breaker's job is to protect the wiring from overheating. It should be set to the smaller of what is appropriate for the aggregate load of all devices on the circuit and the rating of the wire for the distance. Device fuses can provide additional protection when the internals of the device aren't rated the same as the circuit supply them. This would allow, for example, each individual device to be protected from a failure resulting in over-current and heat, while ensuring that the wire as a whole is protected for the greater current it can carry.

5. That concerns me. Unless there is downstream protection, the fuse or circuit breaker has to be rated for the least capable wire in the circuit. So, if you size a circuit breaker for the aggregate load as seen between the bus bar and the circuit breaker, then run smaller wires to the devices, if a device goes whacky, those wires could be overheated. I think you want to run the same gauge of wire the whole way and/or have fuses between the bus bar and the wiring going to the device to protect the thinner wire from being at risk for an over current situation. At an extreme, you could end up needing a main circuit breaker, a fuse for each run off of your terminal block, and a fuse at each device (many devices incorporate one, even if not user replaceable).

6. My own preference is to use heat shrink butt connectors. Depending on the situation they have reducer barrels designed for that purpose. But, you can use ring terminals and a terminal block.

In general, I only use terminal blocks when I need to "branch off" in more than 2 directions or for thick wires. For just 1-to-2 connections with modest gauges of wire, I generally use butt connectors.

 

[jhance]

I think these would work well.

Blue Sea Systems 5045 Fuse Block St Blade Mini 4 Cir- https://www.amazon.com/dp/B01BV1MS1K/ref=cm_sw_r_other_apa_i_4dmvEbRMMTSHJ

The terminals you are referring to, with the back part a larger diameter than the front part... if you are referring to a nylon Ancor terminal, I don't think you want to be putting two wires in that terminal. That larger diameter of the terminal is designed to crimp the insulation of the wire, while the front more narrow section crimps the bare wire. It might work but not as designed and may be an issue down the road.

 

[mvweebles]

When I read the OPs description, I was concerned. When I saw the wiring diagram, I was okay. It is essentially a switched lighting circuit. In some ways, this is a back plane to prevent multiple wires on each breaker terminal.

I agree that best practice would be to place it in an obvious location such as behind the panel, just a a backplane would be installed. Liberal use of a label maker is so in order.

 

[FF]

Terminal blocks rely on the quality of the installation of the terminal end on the wiring.

A good $$$ set tool will make the connection both electrically and mechanically. '

The $3.00 auto shop tool will not.

And use the marine terminal ends , not auto or hardware store versions