What Size Wire Do I Use To Wire My Solar Components? Does Wire Size Matter? 

Not explained more but mentioned, was auto jumper cables. They are designed for large amps (large gauge) ... for a short time... starting an engine should take only seconds. The insulation is more flexible for convenience...on the same rated conductor, the heat generated is short term. Continuous high amp circuits require insulation that is capable of handling the generated heat... so is denser, less flexible than jumpers, and of a different chemical composition. i.e. do NOT use jumper cables as hi amperage cable run, as their insulation WILL melt, causing a short circuit & eventual fire !

Thank you sir for taking the time to make this video, learning is wonderful! One point to make about current and voltages, ratings and specs... Always use a wire gauge calculator, there are plenty of free online ones and charts to refer to (Google for one), to help with calculating gauge, length, conductor type, etc, based on voltage and current. Both factor in, 600v listed on the cable is only the rating for insulation, and safety. One thing for DIY'ers to also understand, is that voltage x amps = watts... So a 1200w load at 12v is 100 amps current, and a 1200w load at 120v is 10 amps, this is why jumper cables on a car need to be very large gauge, and household runs a lot smaller. Length loss matters more as the voltage is lower, higher voltage can travel farther with less loss. That's why on solar it is better to use higher voltages like 48v for battery banks, and higher for solar panel runs, to keep costs lower on cabling, as you are able to use smaller gauge on the longer runs (due to lower amperes). It can get very expensive to use a 12v battery bank if the inverter is not right next to it, as you may need cable that is very large. For example, I just wired an inverter in a guy's RV Trailer where the inverter is in the back, and the batteries are in the tongue by the hitch, and had to buy a 25 ft pair of 3/0 cables (didn't want to use chassis for ground), and cable cost $178... So higher voltage saves lots of money on cable costs.

6/3 with ground - the extra red wire is normally used for a second power circuit so you can run 240 volt equipment (120 volts on black + 120 volts on red ) Yes, it can also be used for a three way switch.

Good video, Thanks... Couple of points. The voltage rating is for the INSULATOR, or plastic coating... it is not for the conductor (copper/aluminum (yes... there IS aluminum... but out of favor and hard to find)) ... the current carrying capacity has to do with the cross-sectional area and metallurgical properties of the physical conductor. Modern wiring sizing is based on cross-sectional area. Stranded cables will actually be physically a little larger than solid -- because solid has no air space between all the strands as there is only one strand. I'm not aware of varying metallurgical formulations for electrical wire on the market today, so theoretically, stranded vs solid wire of the same gauge has the exactly the same current carrying capacity. Voltage and power losses are based on distance, but also by cross-sectional area. Stranded wire is much easier to work with in most applications, and is my go to choice. What WILL impact losses are terminations and turns/bends. having monitored complex cable plants for years using thermal imaging, I can tell you that sharp bends are to be avoided, and crappy terminations, or terminations that are starting to corrode have caused nearly 100% of the failures and pre-failures that needed rework. The remaining miniscule percentage of cable plant fails were due entirely to conductor damage, either manufacturing inconsistency or (mostly) damage incurred during installation and/or maintenance. Current Flows. the easiest way to think of where your losses are/can be is to think of water FLOWING through a hose. If you crimp the hose, flow is reduced. if you place a sharp bend (but not quite a crimp), flow is also reduced. In wiring, this introduces RESISTANCE, and resistance lowers voltage and available power downline. This resistance is also a natural property of the metal used (which is why there are few wiring formulations out there) Personally, I'd prefer to have the cabling sized for at least 150-200% of maximum possible load. This reduces wiring resistance to a cost effective minimum, thus I-squared-R (power) losses, which show up as heat (and can have a runaway effect -- was going to say snowball)

Thanks for taking the time to explain. Very nice high level introduction to selecting proper wire sizes. One note, your guidance on stranded vs solid is not accurate. Solid wire has lower voltage drop but is less flexible, can break under continuous bending and is generally more difficult to work with. Stranded is typically slightly larger in physical size, much more flexible and easier to work with but can lead to higher costs, high voltage drop, higher capability derating and can lead to loose terminals over time due to inherent vibrations of the machinery or the A/C current flowing through it.

Thanks for explaining everything in such an easy to understand way, man.

I did watch 'til the end. I am not an electrician but wanted to know more about the wire. Thanks for sharing!!!

Good info. I'm getting ready to install some solar panels on my RV and it's nice to get confirmation that my choice of wire for the installation is correct.

Current rating (Amps) is a function of the conductor cross section. Voltage and temperature rating is a function of the insulator. Stranded or solid conductors of the same cross section have identical transmission properties at DC or AC frequencies - I'm referring to 60hz. A stranded conductor will have a larger diameter than a solid conductor of the same cross section due to the voids between the strands. Stranded conductors are generally not allowed to be installed in the walls per NEC code. Exceptions apply so consult an electrician. Solid conductors are preferred in applications where the conductor is not subjected to frequent bending or flexing.

Electricity runs on the outside of the wire (strand), so the multi-strand is more efficient. You can use either solid or multi-strand on AC or DC, it is just more efficient to use the multi-strand.

Just a bit of general information to clear up any possible confusion. The voltage rating on the insulation, is just that, it is what the jacket of the cable, be it Teflon, rubber, etc. is rated at. The cable itself is almost unlimited where voltage is concerned. Solid core wires are not going to have more loss per unit length / diameter than stranded cable. Stranded scores in high power high frequency application only. You can think of very high frequency current as wanting to leave the wire altogether and radiate. Skin effect is a phenomenon that increases (decreases depth) proportionally to frequency and only the outer edge of the conductor carries the current. Below about 150hz this is not really an issue. Silver plating is an excellent way to use a semiprecious metal to full advantage here, silver being the best conductor we have presently. Wire carrying current will heat up, the thinner the gauge the greater the resistance per unit length and the resistance to flow causes heat. It's common sense really, what's the maximum current demand on your system? Choose the gauge of wire accordingly. If it's high voltage too, sort out your insulation as well.

Cool...just subbed in. I am running a DIY 4.9KW home off-grid solar power station. I use 4/0 between my 24v battery bank and 3.5KW inverter. Works great...kinda like using a garden hose to drink from a Big Gulp. The cable is actually TEMCo welding cable...with a lot of strands. Zero heating issues...tested with infrared thermometer. Great topic on wires/cables...have fun out there!

Thanx a lot sir, your video help me alot in understanding what wire should i use on my 12v loads running on the entire house. Currently im running thhn#14 and with a mix of speaker wire.

It's folklore that solid core cable has mores losses than stranded. The skin effect only becomes apparent at high frequencies. To the point where if you're moving lots of power around in the tens of MHz range you basically just use copper pipes as no current flows in the centre of the conductor at all. DC has a frequency of Zero Hz, therefore skin effect is not relevant. However, what *can* often happen when solid core is used is that it can be harder to connect to. Screw terminals contact a smaller surface area, where as stranded cable tends to be nicely "squashed" into the terminal well or contact plate thus making a superior connexion. The higher resistance connexion of the solid core can give rise to more heating making the situation even worse in a vicious cycle. The electrolysis action of DC current can also exacerbate the problem. This is likely where it's bad rep comes from. The solution is simple - make a good connexion. Solder a tail on or a lug etc The problem with cable ratings is that they are essentially safety ratings. And with these cables often used on high voltage circuits a certain voltage drop can be tolerated that's no good on low voltage DC systems. If you want to size cables generously, but not go into over the top overkill mode, *Current Density* is a good way to work it out. 1mm^2 cross sectional area per 3 amps is a good rule of thumb for 12VDC circuits. Of course all you Yanks will have to consult your tables to convert that into AWG! lol

Very helpful and I thank you from Chile. Jim

The reason that an appliance is labeled at a specific voltage is because that is how it is tested and the resulting amps at that voltage. A drop of 10 volts from 120-110 in a house is highly unlikely. Three wire NM cable is not only for switches. It is also for stoves and dryers that need 120/240 volts.

Solid wire has less resistance than stranded and thus less voltage drop as distance increases - believe you got this backward. Do not forget about code requirement of increasing amperage requirements for continuous loads by 125%. Current (amps) on hot roofs in conduit have to be further corrected for temperature and corrected again if number of conductors in the conduit exceed 3 wires - Section 690

A easier way to explain sloid wire versus stranded is electricity goes around the wire not through it. The more strands you have the more amps you have compared to a single strand.

That was great, very to the point and informative!

Very helpful. Thank you!

6/3 is for 240v split phase usage...2 hots, one neutral, and ground

Hope you can see this 6yrs after you posted this: I'm installing a 2K watt inverter. Batteries to inverter mounting location is 15'. I decided to go with 4/0 welding cables. My question is: what gauge should I use to ground the inverter to the chassis (semi truck) the inverter came with some doubled-up wires that are stamped 16-8 on the eye-connectors (not sure what that means) Oh ya, this stuff makes my brain hurt 😂

Semi truck battery/starter wire is 4/0 and has very fine strands. And, since semi's have multiple batteries, you can purchase inter-connect cables for wiring batteries together pre-made. Great for heavy solar wiring!

Holy cow. You are the first person I've seen to reasonably explain this so anyone can understand. Great job!

Thanks again Jeff, more help.

Thank goodness for you. You are my best sub!!!

Thankyou for an excellent video!

I looked into moving 12VDC at 10A(120W) accross 80' and found that i needed to run 4/0 cable to do it(very in-practable and expensive) Iron rod would have been cheaper(like a car frame) to keep cost down. Ended up installing a 500W grid tie inverter, and charging the remote battery bank.

Thank you, your video was very informative.

Why solid ware over distance carry less amperage than stranded cable? Because electrons run on the surface of the copper wire not inside. Meaning that solid has less surface area that stranded. stranded are compose of many wires given a more surface area for electrons to carry. Hope it help someone.

Could you answer a question? I have a 30A solar charge controller, with 2 separate inputs, for 2 150w panels, what AWG cable would be needed for this. Thank you.

Keep up the good work!!!!

thanks for the info, very informative.

Great video!!! So glad I found this!! Thank you!!

I got to make another switch. to amazon?!! I'm never gonna be able to get back to red bird district thanks for the up load man

thanks for sharing good video

Man thank you for sharing information.

Great stuff!!!

Thanks a great explination I could understand

Hey Arizona, are you an Electrician? And thanks, I enjoyed the video.

Thank you excellent helpful information

GREAT topic.

Electrons travel on the surface, and stranded has more surface area than solid of the same gauge. And the "RED" wire is "HOT2", black being HOT1, and white being neutral (bare wire is ground). 3 wire is for running 240vac, so always assume Red means dead if your heart gets shorted between it and the black wire...

Thank you for making the video it is very informative

nice video great info thanks :)

You have to fact in the length of the run !

Great stuff. Thanks

Hello I'm new to this but I'm very somewhat confused... where do you find terminals to fit 4/0 awg wire? I had to go to our electric supplier to get the 4/0 wire but they did not have terminals to fit. I looked online but I'm not sure what diameter the wire is. Nowhere on the wire it's self does it say.

I have 110w / 35v solar panel to a 20 amp controller, will I be good with 10 gauge from panel to controller and 6 gauge from the controller to the paired 6v RV battery? Should both be stranded wire too?

If I have 2 24v 305w solar panels and will be running them in parralel going about 15' to charge controller what gauge wire should I use from the panels to the controller? I have a Victron BlueSolar 12V or 24V MPPT 100/50 Charge Controller - 50 Amps / 100 Volts . What size fuse would I need? Each panel has "Current at max power (Imp): 9.33 Amps DC".

Vid was a great help! QUESTION: I'm looking at a new Grand Design trailer. It is "prepped" for solar with a 10ga wire coming down from the roof into the front storage for connection to a inverter. If I get this trailer I am thinking of 600 to 700 watts in panels on the roof. Is the 10ga wire they installed heavy enough to go to a charge controller? Thank you!!!

Super presentation

also if i recall right, AC volts travels mostly center core, where as DC flows easier outter wire (aka more center vs's more outter skiin, least thats what i was told yrs ago.

In Australia it is law in contruction buildings and even RV's to use only stranded. You don't even see that solid copper anywhere here.

Thanks Jeff

4 100watt 5.4amps per panel over a 85'' cable run to an 40amp mppt charge controller. what size wire is best for this application? Take in mind this is just a starter kit and most likely up my panels and battery bank size in future.

Good video helps a lot

thanks so much for this video

Question... I have to hook two 12v 9ah batteries together that then go inside a UPS Battery backup. I have T2 connectors for it, but wondered what sort of wire type/size I should use (the length would be like 2-3 inches).

Can you safe say the higher the Amp the better for any voltage applications. thanks

Your a very good teacher

GOOD INFORMATION

DC current runs on the outside essentially skates on the outside of the wire so if you have one wire solid or you have 25 wires stranded you can see the reasoning for using Stranded wire in all DC applications

thanks now I can set up the furnace in my box van caper the right way. Good exsplanation of wiring.. Make America Great Again!

Old video but helpful, Thanks

Thanks Jeff, Great job !

Solid wire is for static installations such as inside walls. It is cheaper than stranded wire. Stranded wire is for installations that need more flexibility or for applications where the wire would have movement. Large gauge wire would be too difficult to work with if it was solid.

I’m a bit confused on the solar panel wires. I’m recommended to get 4awg wire that will go to the inverter since my solar panels are over 100ft from the house however it’s saying that mc4 connectors only fit 10-14awg. So how does this work?

Why factory just make mark on the cable base on amps ?? Not code .

Do you think I can use 4 ga cables between the batteries in a 12v (4) - 100ah AGM Battery bank in Parallel? Each Interconnect will be aprox. 10" long. or less...won't know till they arrive and I arrange them...... ( BTW... I am Runnin a 2000/3000w PSW Inverter with 1/0 Cables from Battery bank to Inverter at 30 Inches each way)

if a wire has a 600v rating, does it matter if its a/c or d/c. will it pass an inspection if i use a/c wire on my system as long as the volt and amp rating is correct?

I don't see how the losses with the multi stranded wire is less when the resistence is more, it makes sense to me that the resistance is what causes the loss a 12 AWG solid copper wire has 1.588 ohms of resistence per 1000' of wire 10 AWG is only 1 ohm per 1000', but for the 12 AWG multi stranded wire the resistence depending on how many strands of wire in it ranges from 4.76 ohms to 5.18 ohms per 1000' and 10 AWG multi strand ranges from 3.22 to 3.64 ohms per 1000'.

I have two 74w solar panel and two 12v 75ah battery. So what wire should i use to connect them

Finally, someone explains it practically.

I'm having a real tough time finding out what size wire I should use to wire 4 6 volt T-105 225 amp hour batteries in series then parallel to end up with 12 volts 450 amp hours, and how do you find out that information. How should Amps and Amp hours be treated different??

Is 2g wire from the battery to a 2000w inverter okay? 100w 12v panel 10g wire to the 30amp controller 10g wire to the 36ah 12v agm battery

your right on the dc only, my 6 gauge handles every thing i throw at it

What Guage wire do I use for connecting 6x 12v 145ah to make 24v, and a 1800w 3000w surge inverter Guage?

If anything, resistance for DC current on solid core is less than (by less than 1%) than stranded.

Not just amps but insulation type,condition of use and terminal rating.

please i have my 12v 1000w solar panels 20 ft away from the charge controller. what amps of wire can use to draw it?

Does ac come out of the inverter? If so why do you recommend stranded from your inverter to your box? And what about charging from shore power, if your running ac to it to charge your dc batteries would you have to use stranded as well? Thanks for the video, God bless!!

My inverter its burned the last line of fuses 20 amp each one, is 2000 watts current, I change the mosfets but still is burned the last line of fuse, only that the firs and the second is OK. What can it be grong?

what is best for pulsed DC current ?? stranded or solid

i have 18 awg wire motor uses 6 amp and 60 volt power supply will i be safe?

Hi. I have 2 solar panels of 150 watt each (8.5 + 8.5 ampere). Distance between solar panels and charge controller is 8 metres. The AWG table suggests 16 mm square cable. But in market there are only 4 mm square and 6 mm square cables. Is it possible to make 16 mm square cable by joining two 6 mm and one 4 mm (6+6+4 = 16 mm square)? ..................(12 v system)

just cirious can a 60 amp breaker be used for an Air Conditioner

would I use120 feet 2 gauge wire from 20 400w pano 120 feet to the regular?

Well explained

You do not need that big 3 wire for separate light switches. You need them for 3 phase 120v to 240v hook ups for electric stove and dryer.

Stranded is always better cause conductivity depends on surface area. In other words, the stranded one will be more efficient.

Sir one emergency question... A parallel circuit consisting of 2 same load/resistance where the total maximum current is 15 amp. It is protected by 15amp fuse. That means max 7.5 current is allowed in each wires. Now, I removed one of the load. And, I replaced the other second load with new load which consumes max 10amp. That means only one new load is connected in the circuit. That means there's more 2.5amp difference of current flow in the new load circuit. So, in the old load, max is 7.5 per wire. In the new load max is 10 per wire. So, just 2.5 amp difference. Now, coming to my question... If the new circuit is ON say for max 10 seconds, will the circuit immediately BURNS up within 10 seconds??? Of course, it will be hot. How long (30 secs etc) can the wire stay unburnt? How long can it stay safe? Or, How much extra current can be passed beyond the maximum limit for any given gauge wire?

AWG isn't a good indicator of current capacity. I have 14awg, and that's rated for 30 amps, and 16awg at 21 amps. Best way to select cable is read the manufacturers data sheet. I use Farnells for that.

Hello Jeff !

Hi! Very nice video! I am wondering what size wire to run from my charge controller to my gate operator onboard batteries? I have a 24V Liftmaster gate operator installed. Liftmaster will not give me information because "Only certified professionals" are allowed to work on this gate opener. but I am rural, and I want to hook this operator to solar. I have two 100W Grape solar panels hooked into a uxcell Intelligent PWM 30A Solar Panel Charge Controller 12V-24V Battery Regulator PV2430, and on to two 12V deep cycle gel batteries hooked in parallel. It makes sense that I could send wires directly to the DC Battery Power onboard batteries via my solar charge controller.

Thank you for your 'breakdown' explanation!

on the MC4 what gauge wire thickness on solar should i ues on 50 feet ?? 10 gauge or 12 gauge so far no one can tell me most are trying to sell me the big time $$$$$ wire :( any help will be thankful thanks :)

thanks alot

If I need 6 strand can I use 2 / 10 ga in place of the #6?

The fans inside inverters arent designed to install it vertically cause the bearings of fan will fall suddenly.Watch out... The effort in bearings there is axial,and are not designed to do that.