Rewring and Wire size

[ekelly36]

Hey all, just a question, ive tried google and a search here but can really find the answer im looking for. I am doing a rewire of my boat and upgrading the battery and inverter. Doing 900ah LiPo4 and will be adding an additional 4000w inverter. I want to split the loads on the inverters because I plan on adding a AC and doing minimal electric cooking (crock pot/rice cooker/flat plate) Im also installing 1200w solar which ill be running individual charge controllers for each panel. Currently when I plug things into my 120v the plug gets hot, which i know means its pulling too much power in that specific plug, is it ok to rewire everything with a size or 2 bigger guage cable to reduce this heat? Everything ive read has basically said that bigger is better, aside from the cost. Are there any downsides of running larger guage wire?

[capt jgw]

Larger wire being thicker and probably stiffer it can be harder to route through the boat. If it has to go through conduits with other wires it might not fit. You also have to be able to fit the terminals to whatever you're wiring, but going up one size shouldn't be a problem there. Boat AC wiring is often 10AWG, if yours is 12 or even 14 going up to 10 wouldn't be a problem. If your wiring is already 10 gauge, I don't think the wires are the problem.

[JoeRobertJr]

Originally Posted by ekelly36

Currently when I plug things into my 120v the plug gets hot, which i know means its pulling too much power in that specific plug

That can also mean dirty or corroded contacts such that there is resistance heating going on at the contacts. Cleaning the contacts or even replacing the outlets may be in order.

[paul.devalier]

If it's heating up the amps are too high.
A lower gauge (thicker) is generally OK although cost weight and channel size are considerations.
It's best to calculate the right gauge for the amps running through whether it's 12v or 24v or 120v.

When calculating the gauge you need to think about operating environment temperature and the length.
But also shielding and the environment the length will run across.
For a 240v socket (120 in your case) I am going to worry about all the appliances on that socket and then I size the cable and the fuse to that spec .
It is important to follow code and also to make think about the entire circuit. Dangerous and frustrating to have end point appliances wired correctly to a distribution panel but undersized from distribution panel to the power source..
There's only one situation that I have where my "downstream" cable is a lower gauge than cables above it...a very long run from stern to bow for the anchor windlass. Gauge down for long runs.

Here's a few gauge calculators quickly sourced :
https://learnmetrics.com/calculate-w...ge-calculator/
https://www.boatus.com/expert-advice...rect-wire-size

[paul.devalier]

Originally Posted by JoeRobertJr

That can also mean dirty or corroded contacts such that there is resistance heating going on at the contacts. Cleaning the contacts or even replacing the outlets may be in order.

Good point.
Moral : heat not good. Replace.

[fregata]

When it comes to electricity, resistance causes heat.

Possible sources of excessive resistance can be:
Wire gauge too thin
Corroded wire
Corroded connections
Corroded or badly shaped outlets (bad contact)

Larger wire helps by reducing the resistance and also providing more thermal conductivity to dissipate heat. I can’t think of any downsides besides cost and taking up more physical space.

Also keep in mind that quality marine wire is expensive. I wouldn’t go with cheaper wire and simply increase the gauge to compensate for lack of quality. I don’t know the particular standards off my head but a good benchmark is Ancor. It’s important that the wire be stranded, tinned, and that the jacket withstand heat and abrasion.

While you’re at it, also ensure all of your connections are making good metal to metal contact with no corrosion. This would be at the breaker panel, switches, any terminal blocks, and finally at the outlets.

Ancor provides a table so you can look up the correct gauge for your application. For your 120V system you will want to size the wire for current carrying capacity, not necessarily to minimize voltage drop (as one would on the 12V side) so take a look at the table titled “Allowable amperage of conductors of 50V or more”
https://www.ancorproducts.com/-/media/inriver/ANC_BRO_007.pdf?modified=20200402131653
Keep in mind the recommendations are specific to their wire. If you buy something different I would seek suitable guidance from the manufacturer.

[thinwater]

Originally Posted by ekelly36

Hey all, just a question, ive tried google and a search here but can really find the answer im looking for. I am doing a rewire of my boat and upgrading the battery and inverter. Doing 900ah LiPo4 and will be adding an additional 4000w inverter. I want to split the loads on the inverters because I plan on adding a AC and doing minimal electric cooking (crock pot/rice cooker/flat plate) Im also installing 1200w solar which ill be running individual charge controllers for each panel. Currently when I plug things into my 120v the plug gets hot, which i know means its pulling too much power in that specific plug, is it ok to rewire everything with a size or 2 bigger guage cable to reduce this heat? Everything ive read has basically said that bigger is better, aside from the cost. Are there any downsides of running larger guage wire?

You said the plug was hot, not the wire. Big wire won't help with that. You did not state the wire gauge.

[ekelly36]

Originally Posted by thinwater

You said the plug was hot, not the wire. Big wire won't help with that. You did not state the wire gauge.

Im not exactly sure what guage wire is currently installed, it looks to be 12 or 14 but in all honesty it looks just like generic wire you would get from autozone. I can say that the previous owner really had bad wiring habits. I have a decent amount of 12v wiring experience but not alot of 120v experience, behind the breakers are a disaster, nothing is labeled, nothing is protected/shielded. I know that I need marine grade tinned wire which im ok with the cost of and after ive rewired everything I know it will be done right and not look likes a rats nest when I get behind the breakers. I plan on completely rewiring the entire electrical system to my standard but I wanted to make sure as far as the 120v systems and wall plugs that I was ok with going up a size or 2. Regardless there is a world of difference from the kind of work I would do to what was done previously. I just want to make sure its up to par.

[wholybee]

You said "when you plug things" into the outlet. What things are we talking about? A standard 120V outlet is rated for 15Amps, which is about 1500W. I would expect most "things" you plug into the outlet should be much less than 1500W, and should not cause any heating.

If it gets hot it is almost certainly not due to wire size but due to a poor connection, or corrosion on a connection. With the AC power turned off, remove the outlet and inspect it. The wires should be connected to screw terminals, not pushed into holes. And everything should be tight and shiny, nut dull, and most certainly not have any green.

12AWG would be common, and 10AWG a step up and might be a good idea in a marine environment. Of course you should look up in the tables, but in most cases that is what would be chosen.

[Bowdrie]

You mentioned the receptacles getting hot, and a previous post referred to that.
Before making any decisions about wire I would remove one or more of the receptacles to examine them.
Are they the cheap ones that contractors buy for houses that cost less than a dollar at the big-box store where the wire plugs into a hole in the back?
Or, are they the high-quality ones with substantial construction?
AC wiring? 12ga is good.

[NorthCoastJoe]

I would replace the outlets with ones rated for 20 amps. I always use 20 amp professional grade outlets and Anchor #8 heat shrink ring terminals. You have to force the screws past the stops to remove them to use the ring terminals but it's worth the effort. The screws go back in with no problems.

My outlets never get hot pulling high amps for extended times, two electric heaters on the same outlet.

https://www.homedepot.com/p/Leviton-...-00W/202066702

[paul.devalier]

Originally Posted by wholybee

A standard 120V outlet is rated for 15Amps, which is about 1500W. I would expect most "things" you plug into the outlet should be much less than 1500W, and should not cause any heating.

Maybe not the OP 's situation if you have a large genny but for appliances that consume 2000 watts I run them off a double shuko straight from the dock. One arm of the shuko runs into the boat mains. The second through an extension cord runs my electric heater, iron, portable air conditioner, vacuum cleaner, pressure water cleaner and occasionally.
Even with 675Ah house bank I don't run anything over a 1000 watts when I'm away from dock as it drains too quickly.
This setup allows me to avoid any of the wiring of the boat for such items.

[wholybee]

Originally Posted by NorthCoastJoe

I would replace the outlets with ones rated for 20 amps. I always use 20 amp professional grade outlets and Anchor #8 heat shrink ring terminals. You have to force the screws past the stops to remove them to use the ring terminals but it's worth the effort. The screws go back in with no problems.

My outlets never get hot pulling high amps for extended times, two electric heaters on the same outlet.

https://www.homedepot.com/p/Leviton-...-00W/202066702

Do not replace the outlets with 20A outlets unless you also upgrade the wiring. The only difference with a 20A outlet is that an appliance with a 20A plug will fit into it, in addition to a standard 15A plug. The point being to prevent a 20A appliance from being plugged into a circuit wired for 15A.
If someone should ever plug a 20A appliance into a 20A outlet that was retrofitted improperly, that creates a fire hazard. The safer thing to do is upgrade the wires, and leave the 15A outlet(or replace with a higher quality 15A)

[ekelly36]

Originally Posted by NorthCoastJoe

I would replace the outlets with ones rated for 20 amps. I always use 20 amp professional grade outlets and Anchor #8 heat shrink ring terminals. You have to force the screws past the stops to remove them to use the ring terminals but it's worth the effort. The screws go back in with no problems.

My outlets never get hot pulling high amps for extended times, two electric heaters on the same outlet.

https://www.homedepot.com/p/Leviton-...-00W/202066702

I like this idea, thank you.

[ekelly36]

Originally Posted by wholybee

You said "when you plug things" into the outlet. What things are we talking about? A standard 120V outlet is rated for 15Amps, which is about 1500W. I would expect most "things" you plug into the outlet should be much less than 1500W, and should not cause any heating.

If it gets hot it is almost certainly not due to wire size but due to a poor connection, or corrosion on a connection. With the AC power turned off, remove the outlet and inspect it. The wires should be connected to screw terminals, not pushed into holes. And everything should be tight and shiny, nut dull, and most certainly not have any green.

12AWG would be common, and 10AWG a step up and might be a good idea in a marine environment. Of course you should look up in the tables, but in most cases that is what would be chosen.

It was a small space heater that I was using that made the plug hot, I use the same heater at home and I can pull the plug and its maybe a little warm but not almost so hot I cant touch it. On the boat it gets hot enough that the metal prongs in the plug almost burn my hand, I know there should be some warmth but not to that extreme, I stopped using it, what I didnt think about was trying to plug it in to a different outlet to see if it was just that outlet or what... either way upgrading and cleaning up the wiring is on the list of things to do next time I spend a few days on the boat working. It about 5 hours for me to get to it where im at now....