Again, I'm confused?????

[benzu]

As you can see in these pictures these wires are not 12 ga or 10 ga they look more like 14 or 16ga but what I've read everyone says to use 8,10, or 12 ga for the main wire coming off of the battery, then loop the positives but how do you do that with 12ga or even 10ga.

I've figure this out by soldering a piece of copper all the way across and connecting the main together instead of looping.

I still have the problem of the terminal strip. In this picture the negative looks like 16ga or smaller. Don't I have to use the same gauge of wire for the negative as I do for the positive? I have the same terminal strip as shown in this picture and it only allows for smaller then 14ga wire to fit.

I'm really confused everyone is saying one thing then showing another. How do I do this?

Please help!

[brian_bp]

The fuse panel (top) and common terminal strip (bottom) look logically arranged (assuming you like the red+ / black- scheme), other than of course the one bare wire sort of stuck under the left screw of the terminal strip carrying all of the current.

The fuse panel and terminal strip both have the same problem: in each case, you really want a bus bar, but instead have separate terminals and a daisy-chain of wire connections. Yes, this would be awkward to build in thicker wire, and this arrangement also means a large number of connections in series, when you really want several reasonably-sized wires all going to the same common post where a thick wire can carry the total current. The copper strip mentioned presumably creates the desired bus bar setup for the fuse panel; it would be interesting to see how that strip was done.

That terminal strip is a "barrier" strip: there's a plastic wall between each contact set as a barrier, because it is assumed that separate circuits are being connected, and need to be isolated from each other... which is not true at all in this application. Rather than making this work, I would rather just use a simple bus bar, like those used for ground connections or for the neutral wires inside an AC distribution panel. The negative wire of each circuit would connect directly to it, and a single large-gauge wire would connect from one end to the battery. (A Blue Sea example: MiniBus)

A good ready-made fuse/distribution panel would already have the fuse holders connected to a positive bus bar on the supply side, and a negative bus bar for the other side of the circuits. I've never used one, but the Blue Sea products seem widely recommended (and presumably expensive), and for an example their 6-circuit part 5025 has both... and a cover. In their application note you can see the positive terminal beside each fuse, and the negative bus bars with the same number of terminals at the top.

[Joe G]

As you can see in these pictures these wires are not 12 ga or 10 ga they look more like 14 or 16ga

Looks like 18 ga to me.

I still have the problem of the terminal strip. In this picture the negative looks like 16ga or smaller. Don't I have to use the same gauge of wire for the negative as I do for the positive?

Ideally, yes.

...I have the same terminal strip as shown in this picture and it only allows for smaller then 14ga wire to fit.

In terminal strips like these, the limiting factor for wire size is the spade terminal, not the terminal strip. The picture shows blue connectors which are designed for 14-16 ga wire. If you can fit blue connectors into your terminal strip, you should be fine, but you will not be able to daisy chain or loop the wires from one terminal to another as shown in the pic. To solve this, they make terminal jumpers or buss bars to connect two or more terminals on the strip. There are several sizes available depending on screw size and spacing. (They are about $ .05-.11 each from waytekwire.com and there is a $5 minimum per line item, so you may have to buy nearly 100 of them. Waytek part #'s 37211, 37212, or 37214)


For the main 10 ga negative wire you will need to find "narrow block" spade terminals, Where I get them, they have to be purchased in packs of 100 ($15.72 from delcity.net Part #660365 for #6 screw, part #660385 for #8 screw, or part #660305 for #10 screw).

With a little searching, you may be able to find similar products available in smaller quantities. The examples I have given are only from the suppliers I deal with regularly.
delcity.net and waytekwire.com


All that being said, I would like to suggest something completely different. In a situation like this, rather than using a terminal strip, you could use one of these:

It has a 3/8" stud in the center that is connected to 8 #8 screw terminals. I would also consider using one of these for the positive side, rather than trying to solder all the push terminals on the supply side of the fuse block together. They're about $12 ea, and would save you a lot of hassle and allow for easy future expansion of your electrical system.

I'm really confused everyone is saying one thing then showing another. How do I do this?

Hope this info helps you. Good Luck!

Joe G

[Joe G]

....A good ready-made fuse/distribution panel would already have the fuse holders connected to a positive bus bar on the supply side, and a negative bus bar for the other side of the circuits. I've never used one, but the Blue Sea products seem widely recommended (and presumably expensive), and for an example their 6-circuit part 5025 has both... and a cover. In their application note you can see the positive terminal beside each fuse, and the negative bus bars with the same number of terminals at the top.

That's all great advice, Brian.

Here is a (presumably) less expensive alternative:


These ATC/ATO fuse blocks w/ground pad are available from DelCity in 6, 8, 10, and 12 circuit sizes. They cost between $10.77 and $15.88.

[benzu]

Thanks everyone for your help. I figured out what to do I'm not using that terminal strip, I'm using a bus bar instead and so far it works. I'll have to supply pictures as soon as I have the taken.

Thanks again,

Mike

[brian_bp]

...To solve this, they make terminal jumpers or buss bars to connect two or more terminals on the strip. There are several sizes available depending on screw size and spacing. (They are about $ .05-.11 each from waytekwire.com and there is a $5 minimum per line item, so you may have to buy nearly 100 of them. Waytek part #'s 37211, 37212, or 37214)

I had forgotten about those. While I still wouldn't want several of these in a chain to emulate a bus bar, they would be great when you only need a couple of circuits to have a connection in common, in an otherwise separated barrier terminal strip.

...In a situation like this, rather than using a terminal strip, you could use one of these:

It has a 3/8" stud in the center that is connected to 8 #8 screw terminals. I would also consider using one of these for the positive side, rather than trying to solder all the push terminals on the supply side of the fuse block together. They're about $12 ea, and would save you a lot of hassle and allow for easy future expansion of your electrical system.

That's essentially a round bus bar... interesting alternative.

[brian_bp]

...Here is a (presumably) less expensive alternative:


These ATC/ATO fuse blocks w/ground pad are available from DelCity in 6, 8, 10, and 12 circuit sizes. They cost between $10.77 and $15.88.

That looks like a good setup at an entirely reasonable price. Good source!

[BPFox]

[img]I still have the problem of the terminal strip. In this picture the negative looks like 16ga or smaller. Don't I have to use the same gauge of wire for the negative as I do for the positive? I have the same terminal strip as shown in this picture and it only allows for smaller then 14ga wire to fit.

I'm really confused everyone is saying one thing then showing another. How do I do this?

Please help!

I have a problem with the terminal strip as well. Why use one? I mean, what purpose does it serve? If it were me I would run one wire that terminates at the battery negative post. Running separate negative wires back to a common terminal strip is just a waste of wire. Keep it simple, if it doesn't serve a useful purpose, don't do it.

The fuse block set up as shown isn't so bad because it is only running 10 amp circuits. While there is nothing wrong with it, it's not how I would do it. Think of your car's fuse box. Every function has a fuse that is compatable with the function it serves. The wire for that function should follow suit. The main wire coming in should be large enough to handle the whole load and all jumpers should be of the same size. That said, I'm not a big fan of the spade type connectors as they have a tendency of coming lose. Screw terminals will give better performance. If you have to use the spade connectors, take the time to crimp them slighlty with linesman pliers so they stay on tight.

[bobhenry]

I think it is quite adequate for a few small lights or a 12 volt radio or tv .

You can't run a welder on it but so what !

It's a lot neater installation than my 1st and probably will result in a lot fewer fried wires than I had. As we all know you can always spend more money and but pricier parts for our toys, but why !

[Alphacarina]

Ideally, you only want one wire on each terminal post of your battery - One positive one feeding your fuse panel and one negative one feeding your negative distribution block. Adding more wires directly to the battery gives you many more places for corrosion to develop . . . . and it will develop anytime you have a bunch of wires directly connected to the battery. Keep all the wiring as far away from the battery as you can . . . . .

For negatives, it's common practice to use a buss bar and not a terminal strip. The buss bar will have a bolt on each end which you can easily use to connect a very large wire to the battery and then you can screw as many 'grounds' directly to the buss bar as you need . . . . with no interconnecting necesary

http://www.discountmarinesupplies.com/T ... S_BAR.html

I've been wiring boats for many years and a hint for those of you using crimp-on wire terminals - If you solder them after crimping them onto the wire, you'll have far fewer problems on down the road . . . . especially in high moisture locations like marine and trailer applications

Don

[BPFox]

Ideally, you only want one wire on each terminal post of your battery - One positive one feeding your fuse panel and one negative one feeding your negative distribution block. Adding more wires directly to the battery gives you many more places for corrosion to develop . . . . and it will develop anytime you have a bunch of wires directly connected to the battery. Keep all the wiring as far away from the battery as you can . . . . .

For negatives, it's common practice to use a buss bar and not a terminal strip. The buss bar will have a bolt on each end which you can easily use to connect a very large wire to the battery and then you can screw as many 'grounds' directly to the buss bar as you need . . . . with no interconnecting necesary

I'm not going to disagree with what you have said here, but I do have a question or two. Who on this thread suggested more than one wire going to battery nagative? My point was, "Why have more than one negative wire?" Why spend the extra money on running negative wires from each load back to a negative distibution block? What purpose does that serve other than adding the cost and weight of the wire to the build? I say, keep it simple, spend less money. Use the money for gas so you can actually go somewhere. Peace.

[Alphacarina]

Why spend the extra money on running negative wires from each load back to a negative distibution block? What purpose does that serve other than adding the cost and weight of the wire to the build? I say, keep it simple, spend less money

Well, each circuit needs a negative return and you didn't specify what you're doing in lieu of running a negative wire . . . . . but if I had to guess (and that's all we can do since you didn't specify) then I suppose you propose to use the trailer frame instead of a wire for the grounds

You CAN get away with that for the tail lights if you solder everything, carefully clean the frame where you make the electrical connection and then immediately protect the area with paint or something to prevent corrosion . . . . but even then, keep in mind that 90% of the time folks have a tail light that they can't get to work, it's because they have grounding problems and that's usually because they're using the trailer frame instead of a negative wire

For other DC loads (refrigeration, inverters, fans and the like) the trailer frame just isn't acceptible - All of the problems associated with using it for tail lights are muliplied many times over as the current loads increase and poor ground connections can cause all sorts of problems - Motors burning out, overheated connections which melt things and it could even cause a fire

You may consider it a waste of time, money and weight to run an extra wire back from each load to a negative buss but if you want something that's problem-free for the life of the trailer, it's the ONLY way to go. If it's a boat, it's REQUIRED to be done this way to get a certificate if you intend to carry passengers for hire

Shortcuts can save time, money and weight but they aren't always the prudent way to go. There are electrical codes to help keep you on track and none of them tell you you don't need dedicated negative wires

Don

[BPFox]

The frame is the last thing I would use. What I said was I would run one wire rather than multiple wires. Your background is in boats and I have no reason to doubt what you are saying. My background is in dc powered vehicles. (forklifts, scissor lifts etc.) Many of these type of vehicles do not use the frame to carry the negative back to the battery. Instead, they use a single negative wire to carry the load. A single negative wire is more than enough for most of the 12 volt systems being discussed here. If you look at most vehicle wiring systems all of the wires you see are "hot" wires because most of the vehicles use the vehicle frame to carry the negative back to the battery. All I am suggesting is using a single wire to replace the frame in the circuit. Let's say you are feeding your fuse box with a single 10 gauge wire. Then you can carry the entire load back to battery negative with a single 10 ga wire as well. I guess you could say my one wire system replaces the frame and the buss bar. My way does involve soldering "pig tails" along the way as opposed to running wires all the way back to a common buss. Some might think the soldering is extra work. Both systems will work just fine. Mine uses less wire that's all.

[brian_bp]

The other way to avoid multiple negative wires - while still using wires and not the frame - is to daisy-chain the devices... just like the originally illustrated terminal strip, but at the negative side of each device, instead of at a central location.
(While I was typing this BPFox confirmed this was the intention)

This is the approach normally used for multiple devices on one circuit; one positive and one negative wire wander about the trailer, connecting each device in parallel. Lots of the nice drawings people present here of their trailer wiring schemes clearly show this, such as with a couple of lights strung together on one circuit. The same thing is done in normal household AC wiring, as up to a dozen outlets and light fixtures are chained together. In either situation, each circuit has both its own supply wire (12VDC positive with fuse, or 120VAC "line" with circuit breaker) and its own return wire (12VDC negative, or 120VAC "neutral").

... and there's the first problem. If only one negative wire runs to all the devices, it must carry the whole current load of all of them, as if they were on a single circuit. I would rather have a few moderately sized wires to a central location than thick wire going everywhere.
(While I was typing this BPFox confirmed this would be 10 ga; with 60A of fuse capacity I think it should be substantially larger, unless there is also a smaller master fuse)

The other problem is that, assuming you don't use an unbroken single piece of wire with a connection at each device using some sort of splice tap, there are a lot of connections, and any one which fails kills every device "downstream" of it. The eleven marker and clearance lights on my travel trailer are wired this way (they logically are one circuit) and a bad connection at one lamp in the middle has taken half of them out of service.
(While I was typing this BPFox described soldered pigtails... which is a form of tap and would mean a single wire)

In the communications wiring world, sending cables from all devices (such as phone jacks) to a central panel - instead of stringing them together - is called "home run" wiring. Each device has its own run to the "home" (central) location, and that means bus bars and similar distribution devices are needed. It can certainly mean more cable, but it is also more reliable and more flexible (circuit configurations can be changed without pulling new cables).

I think the sensible setup is one dedicated negative wire for each circuit (as shown from the beginning of this topic) all meeting at an ordinary bus bar beside (or even better, incorporated into) the distribution panel. That seems to be how Mike has ended up.


I wouldn't want to use BPFox's method, although I don't question that it works, because

- I can't imagine wanting to make those solder connections
- it likely doesn't save any copper, with the heavy gauge wire going all over the trailer
- modification is more difficult and less reliable, since the single negative wire must be extended from where ever it might end

[Mitch M]

There are many talented and experienced professionals and hobbists on this board. I always find it interresting how many different ways that people approch the same challenge. That being said, I had worked as an appliance repairman for close to 30 years. I've seen many circut failures. some due to enviromental conditions, and many more due to poor connections or poor engineering. Believe me, the repair guy gets to see how "brilliant" some of these engineers are! (Hope I didn't step on any toes out there . Keep in mind when designing a circut that the fewer and cleaner, i.e. soldered connections you use the safer and more enduring your finished product will be . KEEP IT SIMPLE AND SAFE. Just my two cents worth. Have fun!!