best large to small wire connection?

Folks,

A basic question. I have a head with a 12 ga wire coming out of it and have to run quite a distance to the panel board. The head draws 16 amps so the tables tell me to use a 6 ga wire.

What is the best way to step up from 12 ga to 6 ga at the head end, and then down enough so I can hook up to my breaker? do they make a ready connector for that?

I don’t like to connect two sizes of wire directly to each other. In your case I’d use a terminal block.
https://www.bluesea.com/products/2602/Terminal_Block_65A_-_2_Circuit

HopCar said:

I don’t like to connect two sizes of wire directly to each other. In your case I’d use a terminal block.
https://www.bluesea.com/products/2602/Terminal_Block_65A_-_2_Circuit

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+1.

PMF1984 said:

Folks,

A basic question. I have a head with a 12 ga wire coming out of it and have to run quite a distance to the panel board. The head draws 16 amps so the tables tell me to use a 6 ga wire.

What is the best way to step up from 12 ga to 6 ga at the head end, and then down enough so I can hook up to my breaker? do they make a ready connector for that?

Click to expand...

6ga wire for 16A sounds like overkill - are you sure about that requirement? How far are you running that?

http://assets.bluesea.com/files/resources/reference/21731.pdf

It's a 16 amp load with a distance from the battery to the head of 32 ft.

The head pump kept tripping the breaker if run for any time, looked at the PO wires - all 12 ga from the head to the panel board - uh oh.

I see 4 to 2 gauge for that distance. This is the correct chart. Make sure you install the correct load protection too.

Seems to me the suggestion of a terminal block is the best one. There is nothing that I know of that will properly directly connect a 12 to a 6 gauge. And has been said, mind the proper use of overcorrect protection.

Ken

HopCar said:

I don’t like to connect two sizes of wire directly to each other. In your case I’d use a terminal block.
https://www.bluesea.com/products/2602/Terminal_Block_65A_-_2_Circuit

Click to expand...

X3.

Out of curiosity, what kind of head is that?

Xsbank said:

I see 4 to 2 gauge for that distance. This is the correct chart. Make sure you install the correct load protection too.

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Huh? Look again. A head pump motor is not typically a critical voltage drop item.

First question is, however, what is the roundtrip distance from the breaker?

caltexflanc said:

X3.

Out of curiosity, what kind of head is that?

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Must be one for a giant ass,16amps is a huge amp draw in my sense!

L

Mr. L_t...

I have #4 wire feeding the head for the Lectrasan. Total round trip lengths is maybe 12 foot.
Of course the lectrasan has a terminal block on top and much small wires running all over.


The head itself, with its built in macerator, voltage drop not been an issue. Just a standard 12 gauge wire back to the breaker.

RT Firefly said:

Mr. L_t...

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LOL! So not enough holding tank for these invites !

L

Terminal strip is the best answer. In cases were that wasn’t practical l have used spade connectors.

The head is a Jabsco 37010, 12V.

The draw is 16 amps.

I have been calculating the distance from the pump to the power source (battery) X 2.

Using the calculator at Circuit Wizard - Blue Sea Systems I used a 5% voltage drop, not critical, but motors do not like low voltage

The SPX AquaT macerator toilet I bought has a table suggesting a 25 amp breaker and #8 for 40' - 60' run distance.


Did yours come with an installation document with electrical requirements?

PMF1984 said:

It's a 16 amp load with a distance from the battery to the head of 32 ft.

The head pump kept tripping the breaker if run for any time, looked at the PO wires - all 12 ga from the head to the panel board - uh oh.

Click to expand...

Is the cable routing distance the round trip distance or one-way?
Assuming 32 ft round trip:
Round up to 20 amp load (conservative)
Round up to 50 feet length (conservative)
A head is a 10% voltage drop load
From the chart... is #10 AWG. (conservative)

Assuming 64 ft round trip:
Round up to 20 amp load (conservative)
Round up to 65 feet length (conservative)
A head is a 10% voltage drop load
From the chart... is #8 AWG. (conservative)

If #6 will make you feel better, then go for it!
As far as the tripping breaker goes;

1- What is the amp rating on the breaker, and

2- What is the measured current with an ammeter when the breaker trips?

(This is why I always say a cruiser needs to have a clamp-on DC ammeter on their boat for troubleshooting problems. Otherwise we're all just guessing.)

Does the wire to the head run to the battery or to a breaker panel? Hopefully the breaker panel is closer to the head? Only the main feed to the breaker panel and the bilge pump connect to the batteries.

No reason to run 6 AWG wire for a 16 amp load.

I have no problem with 12 AWG, but if you want to run 10AWG that would work as well.

Going back to your originally reported problem which is ths head tripping the breaker I’m thinking that the wire size is probably not your problem.

I always go for critical voltage - why not? A head is a critical voltage, nothing like killing your only toilet out in an anchorage. Gives you one size larger cable and the extra cost will be forgotten in a week after you install it. Besides, what happens to the wire run when your batteries are 12.2 not 13.5 or so and you run the head?

Do the runs for 64 feet and 16 amps? Its obvious to me.

RT, that rhino puts the no-discharge rule in perspective, doesn't it? I wonder how much volume a humpback whale produces?

The OP posted that he is having a breaker operate. He does not even know that it is a wire size issue. He is just guessing at this point.

A logical troubleshooting method would be to measure the voltage at the connection to the pump motor under normal conditions. If the voltage is low, then and only then does replacing the wire make any sense at all, and that would be only done after checking for voltage drop across connections.

You guys may not believe this but 12 AWG wire is used for EVERY household 20 amp circuit in America.

My opinion is to logically troubleshoot issues, then use the data gathered to make rational decisions as to the cause.

Assuming that the wire size is the issue is just an assumption, and may or may not be correct.

Is the breaker sized correctly or is it defective? The initial brief surge current on motor start-up can cause a breaker to trip. You might try a slow, time -delay, high magnetic breaker that can better accomodate the initial surge while stilll providing adequate protection.

While its not "proper" running a 6ga wire the full length then using a terminal end that fits the motor can be done by simply trimming/cutting back the 6ga wire a bit to fit into the 10ga terminal end.

Since its only the last half inch , the voltage drop is not measurable.


Plan B would be to use a 6ga end to end connector and strip the smaller wire for a couple of inches.


Fold it over on itself a few times till it fills the 6ga opening , and swage the fitting.


A strain relief is advised to make sure there is no load on the smaller terminal end , and I would solder after to make sure there are no voids in the connection to corrode.

FF said:

While its not "proper" running a 6ga wire the full length then using a terminal end that fits the motor can be done by simply trimming/cutting back the 6ga wire a bit to fit into the 10ga terminal end.

Since its only the last half inch , the voltage drop is not measurable.


Plan B would be to use a 6ga end to end connector and strip the smaller wire for a couple of inches.


Fold it over on itself a few times till it fills the 6ga opening , and swage the fitting.


A strain relief is advised to make sure there is no load on the smaller terminal end , and I would solder after to make sure there are no voids in the connection to corrode.

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Only issue w above is they ALL go against ABYC recommendations.

Will it work... likely yes initially but can give a false sense of security and lead to issues later.
I would do any of those in an emergency to get home but not as a permanent install.

Ksanders is spot on... do the troubleshooting to identify the issues and then fix that.

Bacchus said:

Only issue w above is they ALL go against ABYC recommendations.

Will it work... likely yes initially but can give a false sense of security and lead to issues later.
I would do any of those in an emergency to get home but not as a permanent install.

Ksanders is spot on... do the troubleshooting to identify the issues and then fix that.

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Trimming out strands if your going to a terminal block to feed a wire sounds bad, but it makes zero difference since your shrinking down to a smaller wire anyway.

You can get terminal blocks with one that has a big bolt and nut to take a large lug. And you can get small gauge terminal ends to go on small wires with a large ring to attach to that bolt.

You could also just strip off the insulation and wrap the smaller gauge wire round the bolt, put it under the larger lug, nut it down tight, then zip tie the wire onto the larger wire so it cant work and shake and bend and break the smaller wire.

Another idea, you could use a nut and bolt and bolt the wires together, then heat shrink tubing over the entire connection.

Another idea, get some soft copper tube, cut off 1/2 inch. strip wire ends. slide copper tube over the wire, twist or place copper wires together and use a vice grip or crimper to squeeze the connection together. If worried about corrosion use oxguard. Cover whole thing with heat shrink.

While it would work, likely draw the ire of a standards body.

I have actually done the soft copper tube idea to eliminate plastic wire nuts in several AC junction boxes on my boat. I joined as many as 4 wires (12-3 gauges) with a short piece of soft copper tube crimped down using a vice grip and heat shrink tubed for insulation.

A few times I have had to make modifications, I was able to uncrimp the soft copper and reuse it again. I have lots of various sized soft copper tubing leftover from various jobs.

I used standard metal junction boxes from Lowes or Home Depot, I painted them with primer, and used screw down wire clamps to hold the wires from being pulled out of the metal boxes. I never have a rust issue yet doing that and my electric system is so tight I run GFCI and AFCI breakers on my entire electric system with no nuisance trips. My boat built in 1970 came with a Square-D electric panel, and couple years ago decided to replace the breakers with combo GFCI-AFCI breakers, and replaced a lot of the AC wiring. Those breakers are the latest engineering, and work ok. Earlier AFCI breakers had issues. My cruisair heat pump does not trip the combo breaker, vacuums work, drills work fine too. I left the fridge out of any GFCI protection just in case since a nuisance trip would be bad.

Those combo GFCI-AFCI breakers work fine with my old Onan gen and a 3000 watt MSW inverter. New combo breakers off Ebay can get good prices compared to Home Depot. Last one I paid $17 for a 20 amp breaker.

Isolated stud. Also 6ga seems like overkill. 10ga only shows a 1 VDC drop over the distance. Also if the breaker is tripping. It's ether too much current, loose connection or the breaker is getting weak and tripping early.

Thanks for all the input so far.

The wires lead to the panel board.

(I'm starting to hate what I've learned reading the posts on this blog as the back of my panel board made me a little sick.)

So the head is hooked up to a 10 amp breaker. That's why it passed gas all the time.

Also hooked up to the breaker are three orange wires - no idea where they go. I have a spare breaker so I will put the orange wires on that and start turning every thing off and on - see what happens. Manual says "The toilet must be wired in a circuit independent of all other accessories."

Will also replace the 10 amp head breaker with a 20 amp breaker.

Yes 6 may be a little large - it all depends on the acceptable line loss. I was thinking along the lines of when the batteries are at the end of charge and the voltage delivered. Also the labor is the big issue here, which is the same with either #8 or #6.

Manual says #6 wire for runs over 40 feet and "Length of run is total distance from power source to product and back to ground." So that about seals the question on wire size for me.

There is a lot of ways to make that pump work and many have mentioned some, but there is only one correct way. Any of these ways will get the next owner rolling his eyes and saying rude things about the "PO." Use the charts to find the correct conductor size and the correct breaker size and run that single circuit to a bus bar by the pump. There you fuse or breaker the pump itself and unless the pump is old and crapped out (that was a pun) and likely needs replacing or overhauling anyway, this should work. The breaker in the box is designed to protect the wire only and it needs to be correctly fused, you then need to protect the device.

In fact, spend some money on Calder's excellent book and do it his way.

Yes, much household wire is 12 gauge, lots is 14 gauge, but its also 120 volts. Go back to the charts and figure it out. That is a bad analogy.

Lou_tribal said:

Must be one for a giant ass,16amps is a huge amp draw in my sense!

L

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I believe my Tecma is at least a 16 amp draw at flush. I watch the monitor on my Magna I/C and it really gets up they when a head flushes.

If you have room for #6 wire, then go for it. You will get excellent voltage which is never a bad thing. I usually go with larger that absolutely required wire since the cost of the larger wire is a rounding error when compared to what I spend on my boat. I would follow ABYC recommendations since some day you may want to sell the boat and a good surveyor may catch the off the wall wiring methods and you may have to fix it then so you might as well do it correctly the first time.