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Terminal block wiring question

Old 11-21-2016, 04:22 PM
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Default Terminal block wiring question

When I attach leads to terminal blocks, should I attach pos and neg for the same circuit side by side, or should I have all the pos together and all the neg together ?

I'm largely using twin core wires so it's simpler to do them side by side.

Note: I'm referring to terminal blocks not bus bars.

Like this: -

http://www.marinco.com/en/products/dc-distribution/terminal-blocks

Last edited by MikeAqua; 11-21-2016 at 05:23 PM.
Old 11-21-2016, 05:07 PM
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Im not sure what you are trying to do, but using that type of terminal block seems like extra work to me. You will have to run separate + and - leads from each one to get power to an individual device.

Im sure there is a code for this, but I prefer to bring the Pos to a single bus bar (as opposed to a terminal block) under the dash for example, and all positive leads go there. There is also a separate bus bar for all the neg/ground leads. They are typically mounted fairly close together so you shouldnt have issues with that type of wire.

Hopefully you are using marine grade tinned wire.

http://www.marinco.com/en/products/d...ution/bus-bars
Old 11-21-2016, 05:14 PM
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In other words, you have a pair of heavy gauge wires bringing power (pos and negative) up to the dash or where ever you need to connect/power multiple devices. Those individual wires need to be sized for the max total load and distance of the run. They also need a fuse/breaker at the battery end.

Then each one connects to its own bus bar and each individual device gets its power that way - through individual fuses or breakers. Some bus bars combine the fuse function.
Old 11-21-2016, 05:16 PM
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These might be more appropriate for you - I dont know.

https://www.bluesea.com/products/cat...and_Insulators
Old 11-21-2016, 05:22 PM
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Originally Posted by Yrral3215 View Post
Im not sure what you are trying to do, but using that type of terminal block seems like extra work to me. You will have to run separate + and - leads from each one to get power to an individual device.
These terminal blocks are where the power leads from individual devices will connect to the leads from the switches.

So for example run the factory leads on light to the terminal block, and run leads from the terminal lock to the switch panel.

It's an alternate to splicing the leads wires together. It avoids to use of splices which may fail, and it mean that the device can be easily replaced without having to separate and re-make splices.

Bus bars are a separate issue. The fuse block I'm using has the positive and negative bus bars built into it.
Old 11-21-2016, 05:26 PM
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Im still confused. In the situation you're describing there would be no negative connections - those would all be going to a common neg bus bar wont they?

Or do your switches also switch the neg??
Old 11-21-2016, 07:43 PM
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On that terminal block all opposing terminals are connected so each such pair must be either positive supply OR negative return. Never positive and negative paired on opposite sides, as that is an instant short circuit.

And even though such blocks are usually used for all positive pairs before the load, they can also have positive and negative pairs on the same block but not same paired terminals. Some outboards for instance use both pos. pairs & neg. pairs on the same block under the hood.

But I believe outside of such mfgrs' careful wiring, "better practice" to help reduce confusion or potential shorts is to use separate terminal blocks for all pos or all neg connections.

Remember , generally speaking all supply leads before the load are positive and all leads returning from the load are negative. The terminal block is not a load, only a junction connection point .
Old 11-21-2016, 07:55 PM
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i think he's just using it as a junction, not a distribution point.
Old 11-21-2016, 08:08 PM
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You should use two of those, called Barrier Strips' (used for NMEA2000 instead of tees) one for positive and one for negative and keep them well and truly separate by couple of inches to avoid shorts.
Describing just the positive strip...... You need to connect the supply to one end usually the top and daisy-chain down to each terminal. Same for the negative strip.
The loads then connect to the screws on the opposite side.
This keeps things neat for cable tying.
The 'loads' connected on the screws goes to the fuses first then the switches. This protects the switches from shorts should they have a negative connected for illumination and develops a fault.
Old 11-21-2016, 08:13 PM
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Originally Posted by TTaxi View Post

"better practice" to help reduce confusion or potential shorts is to use separate terminal blocks for all pos or all neg connections.
Thanks for your response.

The reason for my question is I am running most of my wiring as twin core. I thought it would be easiest with the twin core to have the pos and neg leads for each circuit terminate on separate but adjacent pairs.

But I can see that would make it easy for there to be an accidental short circuit
Old 11-21-2016, 08:21 PM
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Originally Posted by isitstuffed View Post
Describing just the positive strip...... You need to connect the supply to one end usually the top and daisy-chain down to each terminal. Same for the negative strip.
Thanks for your response. I'm using the terminal blocks purely for junctions, as the factory leads on all the loads are of course too short.

The positive blocks will be between the switches panels and the loads.

The negatives between the loads and the negative bus on the fuse block.

The fuse block has positive and negative buses built in so it seem easier to use this.
Old 11-21-2016, 08:23 PM
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I didn't get a clear picture of the issue, but if at all possible you should have a separate negative buss bar and positive terminal block. Better still instead of a positive terminal block, use a fuse block where you can make the connection plus have a fuse thereby eliminating all the in-line fuses.
Old 11-21-2016, 09:21 PM
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I understand what your saying and don't see a problem with it, however it would probably be better to have separate connectors for pos and neg to save confusion for anyone other than you who might work on it.
Old 11-21-2016, 10:44 PM
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if you are using them as a junction then put the pairs together. if you are trying to use it as a bus then put them on separate ends and buy the proper jumpers to jump the screws together.
Old 11-21-2016, 10:45 PM
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Originally Posted by Gnrphil View Post
I understand what your saying and don't see a problem with it, however it would probably be better to have separate connectors for pos and neg to save confusion for anyone other than you who might work on it.
it's a duplex wire. you strip back 2" and connect both to block. not very confusing to figure out
Old 11-22-2016, 10:26 AM
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Originally Posted by knotreel View Post
I didn't get a clear picture of the issue, but if at all possible you should have a separate negative buss bar and positive terminal block. Better still instead of a positive terminal block, use a fuse block where you can make the connection plus have a fuse thereby eliminating all the in-line fuses.
x2 Only way to go.
Old 11-22-2016, 10:34 AM
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I have only seen it done with 2 separate blocks so the circuits can share a common supply and a common ground.
Old 11-22-2016, 03:24 PM
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I buy the negative Buss bar for # 6 or # 8 screws. This is for all those small and short wired things to get to a 0 volt point.

I put a 15 or 20 amp BARRIER TERMINAL about 3" away from it. this set up allows you to connect the device + & - leads to terminals opposite each other. Using their leads with terminals. The opposite side of the barrier terminal goes to whatever. Switch. The other side of a switch goes to the load side of a fuse strip or Circuit Breaker terminal strip.

I try to keep all the wires for 1 device in a orderly sequence. You can buy fuse or C B strips with factory, heavy duty, jumper strips. Or make your own jumpers from your own stripped stranded wire.

Simple to do . I always use a # 8 + 12 volt feed wire to feed the first high current devices. Small anchor winches or up to a medium sized trolling motor. Then reduce the fuse block feed wire to # 12 for all the smaller stuff.

There is a fuse very close to the battery to protect that main # 8 feed wire from shorting & melting into a mess. USCG code.

A battery with big automotive lead posts AND the wing nut post is ideal for DIY rewiring. Simple to trouble shoot. NAPA sells fuses & fuse holders for # 6 & # 8 wire loads. I avoid those metal AUTOMATIC resetting circuit breakers. They do corrode in fresh & salt water areas.

There are loads of barrier & circuit breaker strips Now with a clear plastic cover to shed most water & causing accidental shorts. I spent about 1/2 hour one day surfing from electrical site to site.

It is all on the web. Take the time.
Old 11-22-2016, 06:25 PM
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Originally Posted by smac999 View Post
if you are using them as a junction then put the pairs together. if you are trying to use it as a bus then put them on separate ends and buy the proper jumpers to jump the screws together.
Thanks, I am using as junction blocks

It's purely a secure and tidy way of lengthening the short flying leads that all the loads come with.

The fuse block I'm using has positive and negative bus bars built into it.

http://www.narva.com.au/products/det...s-popup-layout
Old 11-23-2016, 06:31 AM
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Perfect
I will see if the amperage is high enough for some small Dockmate winches on the 16 foot Lowe. I used the old fashioned separate different Bars & fuse blocks.

Thank you !!

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