How to Size Fuses for a Camper Van Electrical Setup

[@xlamontx]

"The fuse protects the wire." So critical to the basic understanding of an electrical circuit. Thanks for another awesome video.

[@EXPLORISTlife]

For sure! Thanks for watching, Lamont! ✌

[@berthaduniverse]

Almost every question I have, you seem to have a video covering most of it! Thanks Nate...

[@EXPLORISTlife]

No problem. Happy to help!

[@stevecrowe176]

Hi Nate from Australia. Love all your vids, thank you. I'm a 1st class sheet metal worker, can put together a offset square to round ducting, this DC stuff is a challenge I'm trying to learn, as I'm sure you'd have a challenge in ductwork. Each to their own. Now, don't have a camper van, RV or motor home, just have a normal vehicle towing a box trailer for the swag and gazebo. When 240v is unavailable I've purchased a battery box, 100ah lithium battery, battery monitor and shunt, 2 x 12v cigarette outlets, 1 x 5v 3A x 2 quick mobile charger outlet, 2 x Anderson plugs, 1 x solar dedicated Anderson plug, 6 outlet blade fuse box, and a 1500w pure sine wave inverter (3000w peak) Ohh and a 360w solar panel. Pretty sure on wiring everything, each positive cable with a blade fuse, just stuck on inverter wiring huge amps, cable size, either ANL fuse or Class T fuse or ANN fuse someone mentioned earlier. It's all mounted on a battery box. Handy for power black outs (or brown outs) in NSW to run the fridge and TV being so portable. You've covered RV, motor home, camper van 12v fit outs with almost every conceivable wiring diagram scenario. Is there any chance you can provide different wiring diagrams for the budget end of camping similar to my set up for all the other campers? Thought I'd ask. If you've read this far, thank you! Cheers

[@EXPLORISTlife]

For something that small, I'd just recommend getting a Goal Zero or similar; which is why I won't make a diagram for a system that small. But if YOU want to DIY it... that's fine... This channel has all of the educational material you need to make it happen; you'll just have to do a bit of additional due diligence.

[@SpantuCatalin]

I'm second for that.

[@rafaelbenz6375]

Great explanation! Just to clarify for many here, that distance used in the example needs to be double. So, it is a 50ft wire run (round trip). I have the ABYC E-11 & comparing it to Blue Sea Systems charts (which are supposed to be based off of ABYC) their figures are a tad different. In the same example he gave, the ABYC suggest 4AWG while the Blue Sea Systems charts (colorful quick chart) says 6AWG. Just double check & take your time when doing your wiring (or use the calculators he's made) Thanks for the awesome video!

[@SawmonandNatalie]

why does the distance need to be doubled?

[@s.mendez7160]

@@SawmonandNatalie The electricity runs from the source, to the load, and then back to the source to complete the round trip path of current flowing thru the wire. Voltage drop along the wire is calculated using the total wire run length.

[@sebastianlehmann3698]

If it is not in boat or your load isn't that big, I will go as Nate says and do a common sense, go for the 6. ABYC add a lot of room when do calculations just to be always in the "SUPER SAFE" side of the calculation.

[@rafaelbenz6375]

@@sebastianlehmann3698 Yes Sebastian. The super safe is the 4awg that I mentioned. Thanks for commenting & staying involved!

[@sebastianlehmann3698]

Lol sorry yes the 4 is the SUPER SAFE.

[@Farseer1995]

You deserve not only hundreds of thousands of more subscribers, as you literally go step-by-step through everything a noobie could need help with, but also a nobel piece prize. :)

[@EXPLORISTlife]

Glad it was helpful. Cheers!

[@MicBergsma]

Funny I just found this video after using your calculator two days ago, thank you for this!

[@EXPLORISTlife]

Hey Mic! No problem. Happy to help! Love your channel. I need to do some catching up on your VW Bus resto. Looking great!

[@MicBergsma]

@@EXPLORISTlife hey thank you! Your video is helping me out for setup for VW bus! And I am planning to say about your calculator in the video and send people to your link 🙌🏼 I added up all amps from 5 accessories that will be about 58 amps so I go for 60 amps then calculator say recommend 75 amps so I am gonna get mega fuse 75 amps and still figuring out which amps on big relay in between new fuse box and mega fuse… 80 or 100 amps 🤷🏼‍♂️

[@patheticprepper4496]

Wow, deep, fuses protect wires!

[@christiancowboy352]

Awesome! That is the last thing I was needing to fully understand. I think I do, but sure need confirmation. I can't wait to see this video. Thank you for taking the time and thought to do all these videos for us. Many of us sure can not afford to hire someone to install our solar systems...Thanks again, you a greatly appreciated.

[@EXPLORISTlife]

Awesome! Glad it helps! :) :)

[@explor794]

Your the best Spokesman for Victron, their other video’s are kinda dry.

[@crashtestdummy2686]

This was the one thing I needed to complete the solar setup for my van project. Thanks for making it easy to follow an simple for those of us that don’t know squat about the subject. I would hate to blow up any of the equipment or worse yet start a fire in my van.

[@thehastywombat]

Awesome, I'd checked out your calculator a week or so ago, but this video cleared up when and how I might use it. Love your work.

[@EXPLORISTlife]

Glad it was helpful!

[@STMel03]

How does one go about sizing fuses for the main components such as battery bank to switch/busbar, busbar to inverter, busbar to DC distribution block? 300AH Lithium & 3000w inverter .. I've got all of the other 12v items fused thanks to this video! Thanks again!!

[@EXPLORISTlife]

It's the same way. Still figuring up to 1.5 of max load given 1.5x max load does not exceed max ampacity of the wire. But if you are looking for fuse sizes for a system with a 3000w inverter, you should check out this diagram: www.explorist.life/3000w-inverter-400-600ah-400-to-1200w-solar-camper-solar-kit/

[@mub3ady]

Thanks Nate appreciate it. I have a 4 battery system (4 100Ah batteries serial/parallel 24 volt connection) and my fuse requirement as per your instructions I calculated is 125 amps Should I put one 125 amps on the common positive cable going to the hybrid inverter Or divide it and put four 32 amps on each positive pole instead ? I thought of 4 fuses for all positive poles is more safe, but may be I am missing something, so your advice is Apreciated. Thanks

[@DrDGr2]

Url for the previous video would be nice…. Thanks your your videos!

[@merrillbalan]

Thanks for doing all the hard job for us....I have 2x 3000 watt inverter in split phase and have 2 sets of array of solar (6x 330watt panels 3 in series and 2 in parallel and second array 16x 100 watt panels 8 in series and 2 in parallel ) 4x 24v Lifepo4 100ah in parallel (24v 400ah) can you list the fuses and breakers and cable size that I would need thanks!

[@36Hooters]

Hey Nate love your videos mate. But would love to have the options for metric sizes, specially in cables sizes and lengths. Even if the American sizing had the equivalent metric size next to it. keep the vids coming.

[@EXPLORISTlife]

Good idea!

[@jimeverett8998]

Love your channel Nate! You're very meticulous and a master craftsman. I'm building portable power systems and I've order some Taixi DC circuit breakers for my main Battery disconnect/protection. Specificaly, DC12V 24V 48V 300A breaker part number is a bit challenging to determine give poor communication with the seller in China. I payed ~$75 each for the 300A rated one. Curious if you have looked into these.

[@jeffhuber3411]

What about a video on WHERE/WHEN a fuse is recommended/required in a solar build? Is "best practice" a fuse on every run between two components? Should the fuse be close to the load or the power supply? etc

[@aaront8396]

Great idea. I think many people would enjoy that video. Thumbs up 👍👍

[@AaronGeller]

Almost everyone has the fuse close to the battery. Now this could be more of a practical thing as having everything in one spot makes it easier to switch out the fuse. Most people have a fuse box so it’s naturally closer to the power source.

[@EXPLORISTlife]

Will keep that in mind. Thanks for the suggestion! For the time being, there needs to be a fuse protecting EVERY wire and the fuse needs to be on the side of the wire closest to the source of power (battery side).

[@andrewthatcher7409]

I know this is older, and we fuse for the wire However, in a main battery fuse do you need to account for incoming amperage from a solar charge controller and a use from inverters draw, or just the use side or inverter?

[@anthonybombay9621]

Nat, What an amazing gift you and your wife have. I purchased your wiring diagram for the 3000 W inverter up to 1200 W solar. It shows the fuses on the Victron Busbar but I'm using the 120/80 Victron controller to manage 800 W and I don't see the fuses listed for that busbar. Wouldn't they be different sizes? I appreciate your help.

[@GirdHerd]

Hi Nate, One of the solar installers on a FB group I belong to is recommending a 400A Class T fuse instead of a 400A ANL fuse at the battery bank. I have already purchased the ANL fuse and holder but am willing to buy a Class T fuse and holder if you think I should. I trust your judgement more that any of the installers in the FB group and would appreciate your input.

[@EXPLORISTlife]

Both ANL and Class T Fuses have Ampere Interrupting capacity high enough to be used as the main fuse at the battery bank as per ABYC E-11 Table IV: www.blackfinforums.com/sites/default/files/10/attachments/abyc-e-11.pdf I recommend ANL fuses as the main fuse in ALL of my diagrams & parts lists found at www.explorist.life/solarwiringdiagrams as they satisfy the aforementioned requirement and the are a little less expensive than Class T fuses. (Note: High Quality ANL Fuses & Fuse Holders like Blue Sea, LittelFuse, or Bussman are HIGHLY recommended and are listed on each of the diagrams from the previous link.)

[@GirdHerd]

@@EXPLORISTlife Thanks, Nate.

[@wfdTamar]

In your fuse & wire size calculator could you please also list the wire size in mm2?

[@EXPLORISTlife]

It's not a priority, no. There are conversion charts out there, though.

[@DustyKorpse]

As always a great vid!

[@EXPLORISTlife]

Thanks! 👍👍

[@reelbigstudios]

Great video as always, Nate - thank you. Just to confirm: For all my small 12v branches throughout my van, I decided to use just 2 different wire sizes -- so then all the blade fuses in my 12v fuse block will be only one of two sizes, according to the wire alone - and not at all related to the devices/ expected load on each, correct? i.e. Not trying to protect the device, but only the wire size.

[@PaulLadendorf]

If I've got a 10A 48V inverter but I'm using 12 ga wire, does that mean the fuse between the batt and inverter should be 20A? Thanks much.

[@sarahallgood798]

Thank you for this

[@EXPLORISTlife]

Hey Sarah Allgood, No problem! Glad it helped! :)

[@bauefrenchmen3126]

Does the length mean just the red and black wire from batteries/inverter or does it include the length of my extension cord into my rv assuming its the same gauge as the red/blacks?

[@pretread]

very informative ..thanks

[@jahkingdom]

Hi, on your wire size calculator on the website, I put in amps = 55, voltage = 24v but it recommends 10awg. If I search max current rating for 10awg wire I get 30amps!! Bit less than the 55 so what's the deal, am I wrong, is the calculator wrong or what?. Very confused now. Great site and videos by the way👍

[@EXPLORISTlife]

Different 10ga wires are rated for different amps. Look up the max amps for 10ga wire with 105 degree insulation (what the calculator is set up for).

[@sailrockpaperscissors8261]

great content where do i find the free wiring diagrams with wire sizes you mention thx

[@EXPLORISTlife]

They are all at www.explorist.life/solarwiringdiagrams

[@teodortoshev8386]

Hey guys, just a question that popped upcin my head. I recently found that there are ANN fuses also, they have a very short blow time vompared to ANL. ANL fuses are typically used in sound systems. So, why is everyone using ANL i stead of ANN, any reason for that? Much appriciated!

[@Salsadepr40]

Hi Explorist, I enjoy this video that helps me throughout the process of my van conversation. I was wondering if it's possible that you can please help me with a DIY? I am looking to find out how to install my cable wires to my alternator to get 220 AMP. I have a 2021 ProMaster 2500 series 159w base with a 220 AMP alternator built in but I haven’t found a video showing this type of installation. Can you please advise me if possible? Thank you so much in advance. I will post a video on my installation once I get the info.

[@grnladybuglouviere2956]

Hi and thanks for the super informative video. What i am having trouble finding is what size fuse to put on the wire between the Positive bus bar and the DC fuse block. How would i go about sizing that?

[@douglashammond2147]

Great Info With your DIY Negative Bus Bar and Master Service Battery 12 V DC Disconnect Switch setup. (...understanding you don't recommend this anymore because of fuse quality issues) . Previous instructional videos (other users) show a Renogy 50 AMP- DC/DC MPPT Charger/Controller connected via Fused bus Bar to the always HOT side of battery the cutoff switch. The negative DC Fuse Box / Charger/Inverter wires connected to other red negs on the opposite side of master cutoff Switch. Why are not all negatives /reds on the Not Hot Side of the master Battery Cutoff Switch under this scenario? Does it matter and or why?

[@EXPLORISTlife]

That could be for if you wanted to turn off all loads but allow charging of the battery. I don't see this as a big issue as you can simply turn off all loads at the device similar to how you'd turn off the lights at your house at the switch instead of turning off the master breaker in the breaker box.

[@joshneff6877]

I have learned i can not afford to do a solar panel addition to my trailer. So, if i understand the video right, i can install new batteries and a charge controller with an inverter/charger. Am I correct? Then at a later date add the pannels? Due to the price, I chose 4 12v AGM 100Ah batteries. I am trying to use your chart but without the panels.

[@tanesiaapodaca569]

I would like to speak with you about getting your assistance for low voltage wiring.

[@EXPLORISTlife]

Certainly! You can put down a deposit for installation services at shop.explorist.life -> Menu bar -> Services -> Installations Our installation team looks forward to hearing from you so we can move forward with your project.

[@MrPoppabear255]

Great as always!

[@MarkDano-t9c]

Do you have a free drawing of a 12 volt system that does not have solar, an invertor or a convertor?

[@boscodog4358]

Where can I purchase the bussbar materials

[@91nikolai91]

How come you don't include the solar power in the main cut-off switch? :)

[@cali-electro-dad]

Hey Nate! You state that 4 AWG has a max capacity of 160A... the DC charts I'm finding say 100A at the shortest lengths. What am I missing? As an electrician (granted residential) this seems nuts to me.

[@EXPLORISTlife]

Sure! ABYC E-11 Table VI-A tells the max ampacity of a wire before any derating factors. Here is the table: E-11 Table VI-A: assets.bluesea.com/files/resources/reference/21731.pdf The wire must meet the specifications of E-11 (Fine stranded wire, 105 degree C insulation, etc.)

[@cali-electro-dad]

@@EXPLORISTlife Got it! Coming from residential AC I'm used to being limited by the ampacity of the terminal I'm connecting to for branch and feeder circuits, for AC beakers that's a max of 75 degrees C, so the only time we can rate a wire higher is if derating for heat or when not landing on one of these type of terminals. Does the same logic not apply in DC? For instance I'm considering this breaker for use in my system... www.amazon.com/dp/B08DD313G9/ref=cm_sw_r_cp_apa_glt_fabc_S5K5V8XBMC757EJA6BDB It's rated "work temperature" is max 50 degrees C. My understanding tells me that I would then have to rate my wire at 50 degrees C no matter it's insulation rating because the weakest link is now the terminal on my breaker, but I'm not finding any DC breakers with higher working ratings than 82 degrees C, so I may be barking up the wrong tree.

[@stevecrowe176]

Not sure where you are Cali it's the same for Australia, 100A for 4awg even if less than a 1M length! I think the temperature ratings for the cable come into play as well, Nate is always mentioning "105C" when providing AWG/Amp rating/statistics.

[@MikeJones-rk1un]

How do I fuse a 12v, 100ah battery? Circuit breaker?

[@DIY12-24v]

Hi. I been trying to find out what max amp load of wires are without factoring in voltage drop. Would you know a good source to find this information?

[@CoolStuff..]

cool

[@Peppins]

I don't understand a thing (even from the calculator above). If i increase the voltage leaving the "device amps" the same, it continue to say to use the same fuse. How is that possible? 10A at 12v = 120W, 10A at 120v = 1200W, it's totally different. For example i have a 72v battery pack at home that i want protect with a fuse or dc breaker. The automotive fuse are rated 12/24v, it will work the same at higher voltage? I doubt, cause the ampere/watt (converted to rated current) will be higher, or i'm wrong?. The same for the dc breaker that are rated with a range value (example 12-500 or 12-800 DC). I mean the same type of the one used at home for the AC, there are also for DC. How is that possible? 10A at 12v will be different that 10A at 500v. The thermal protection (fuse, breaker) will not be the same at same Amp but different voltage. So how it work?

[@EXPLORISTlife]

Yep, it's totally correct. That's why we need to use a 2ga wire to power a 1200W inverter operating at 12V (1200w / 12v = 100A) but can use 14ga wire to power a household 1200W space heater operating at 120V (1200w / 120v = 10A).

[@EXPLORISTlife]

You just need to make sure the fuse/breaker is able to handle the 'type' of voltage (ac vs dc) and the level of voltage (24v max vs 48v max vs 250v max, etc)

[@Peppins]

@@EXPLORISTlife Ok but the problem is still there. How a dc breaker can work correctly if it's rated with a range value? Example 12-120v dc 10A. How it can trip with 10A at 12v (120 watt) without tripping at 1A at 120v (same 120 watt)? I don't understand. The ratem amp (10) of the example, are 120 watt at 12v BUT 1200 watt at 120v, so the heath of the thermal protection/breaker will be different :S

[@EXPLORISTlife]

@@Peppins Amps trip fuses. Not watts.

[@Peppins]

@@EXPLORISTlife Wait, maybe I get it. Since everything is based on thermal protection, is the heat released less at a higher voltage, even though there is always the same wattage? Perhaps this is why in DC with low voltages but at high amperages thicker cables are needed compared to higher voltages and/or in AC?

[@Alpha-ms9nj]

I'm putting together my first solar setup. It's a basic 200watt, single 100ah lifpo battery with a 2000watt inverter. For my battery to inverter wire, according to some sources, they recommend using the following formula, 2000w /12V = 166amps. Then they say to multiply that by 1.25.(not 1.50)? so 166amps x 1.25 = 208amps. Then they say to add the amps of my 12V fuse panel which would be 15amps max and add THAT to the 208amps for a total fuse/breaker size of 223 amps. Is this ok to use this formula? I don't know whether to use a 220 amp fuse/breaker (don't have one) or move it up to 250amp which I do have on hand? I hope you can clear this up for me if you have the time, thank you.

[@EXPLORISTlife]

I don't think I have any more insight than what was in the video. If you're still struggling with the concepts, perhaps just following one of my 2000w inverter diagrams available here will help: www.explorist.life/solarwiringdiagrams.

[@rayleeson6135]

If you size the fuse to protect the wires, how do you size a MRFB fuse? ….is it sized to protect the total load….even though that load may be variable…even quite low?

[@aaronrezentes179]

Hey Nate, thank you so much for all the great videos and information. I downloaded your 120v and 12v branch circuit diagrams and noticed that you show a Dometic AC unit on 120v power but I dont see one on the 12v circuit diagram. For some reason i was thinking that 12v was the preferred route for an AC unit but now Im wondering. I am using the Multiplus 3k with 400 Ah of Battle Born batteries. Is it preferred to run a 120V AC unit? Thanks again!

[@EXPLORISTlife]

12V is also fine. That wouldn't be included in the '12V branch circuit diagrams' because that wire is much bigger than would fit in a standard 12V fuse block (what that diagram is for). A 12V Air Conditioner would get connected to the Lynx Distributor in my diagrams.

[@jesse7113]

Hi, any reason why the charge controller is not behind the isolator? It is not like that on your other plans. Heard solar should always be connected to a battery, is that the case?

[@EXPLORISTlife]

The minor benefits don't outweigh the 'pain in the ass' to wire together the wire on the battery side of the isolator. It's just so much easier to use the Lynx Distribtor like I have in all of my diagrams now at explorist.life/solarwiringdiagrams.

[@kconatymd]

I just discovered y'all today, Thanksgiving. Awesome, thank you! In the spring I am about to launch on a Lithium conversion of a Winnebago Travato Class B van. It has solar already, and I will add more but a question I have for you is: I notice that your diagrams all show PV panels in series. Winnebago already has 2 extra plug ins on the roof for extra panels, but the panels will be in parallel. I don't think that it will be worth changing everything around to have them in series. What say you?

[@EXPLORISTlife]

I very much like wiring panels in series. Here's why: www.explorist.life/solar-panels-series-vs-parallel/

[@theroadnottaken9378]

have you done anything on incorporating a dc to dc charger in a system. thanks.

[@EXPLORISTlife]

I don't have a video on it YET, but my newest free diagram has a DC to DC charger on it: www.explorist.life/3000w-inverter-400-600ah-400-to-1200w-solar-camper-solar-kit/

[@nyilaszsolt9790]

Hi Nate, I'm about to buy one of your wiring diagram ("3000w INVERTER | 400-600Ah | 400 TO 1200W SOLAR -CAMPER SOLAR KIT") Before buying I would like to ask you about its compatibility. It can be adapt to a 230V (Europien) system without any changes? I mean the size of fuses, wires, AC brakers are the same size and rate if I do this with a Victron MultiPlus 12/3000/120-16 12V 230V? Possibly do you have a European version of this? Thanks in advance.

[@EXPLORISTlife]

The DC side of things would be the same. AC side would change to fit 230V.

[@nyilaszsolt9790]

@@EXPLORISTlife Can you do the changes or I have to do the calculations after purchase the diagram?

[@EXPLORISTlife]

That'll be on you based on all of the tutorials I have laid out here on this channel and what products are available to you in your country.

[@nyilaszsolt9790]

@@EXPLORISTlife Thanks

[@jennycantrell8661]

How can you tell how much power should come out of an MPPT Charge controller? My thinking my be wrong, but if I wired solar panels as series/parallel and have 8 100w panels going to a charge controller. I would have 70v 11.38a 796.6watts So this is approximately what goes into the charge controller, (this is where my thinking may be off) but the charge controller takes the high voltage down to a manageable voltage for your battery setup (ie 14.4 volts) but does it also convert the extra volts to AMPS? If so at what rate? So essentially what I am asking is since I know what is going into the Charge Controller from the solar panels, what would that equate to in amps coming out of the charge controller to the batter bank?

[@EXPLORISTlife]

Solar array wattage / battery bank charging voltage = charging current (amps) headed into the battery bank. 1440w solar array / 14.4V battery bank charging voltage = 100A heading into the battery bank.

[@استغفراللهوأتوباليه-ر6ث1ر]

Hello sir , I have question can I ask you ?

[@RossWA1956]

I am a "tad" confused and hopefully someone can help, I am creating a 24v system and using 24v Inverters with 240v Appliances. I'm not shore if my "Amp Draw" calculation should be "Appliance Watts" / 24v or 240v to size my cables, any thoughts?

[@EXPLORISTlife]

Ask yourself: When the power is flowing through the wire in question... is it flowing at 24V or 240V?

[@RossWA1956]

@@EXPLORISTlife It is Drawing 240v from the Inverter but only 24v into the Inverter, so the calculation is based on In or Out correct?

[@miketravis3961]

hi nate. what does DIY CAMPER SOLAR TOOLKIT consist of? not sure I received anything thanks mt

[@EXPLORISTlife]

Check your spam folder?

[@firpofutbol]

It seem odd that the fuse be sized bigger than the wire ampacity spec. It may not be code but I do it a different way: The fuse is 125% of the load, and the wire ampacity is 150% of the load. No way that wire comes close to catching on fire but that's just me. 😁

[@eksine]

I don't get it, you say the fuses are to protect the wire not the device, but than you finally say to just size the fuse to the load which in this example was 15 amps with a 20 amp fuse. so didn't we just go around in circles? so basically I can use a fat oversized wire and still just size the fuse for the load which could be as little as 15 or 10 amps?

[@EXPLORISTlife]

Correct. It is indeed confusing and it does send us in circles a bit, but that's how electrical code reads. "Sizing for the wire and not the component" means that your fuse can and should be higher than the component. If I were to say to size the fuse for the component, people would have a tendancy to size for the amperage output of the component, say, putting a 50A breaker on a 50A charge controller; which would regularly trip under normal operating conditions.

[@eksine]

@@EXPLORISTlife oh I see thank you, yes I've heard it's a rule to size the fuse for 20 or 25% larger than the component. Your math makes it more clear thank you

[@TerrydeAlaska]

I know you know what you're doing, but where does it say in ABYC that this pertains to camper vans? Shouldn't you be referencing in NEC, the national electric code?

[@EXPLORISTlife]

The ABYC doesn't reference camper vans or even RV's for that matter, but since marine systems involve a LOT of similarities to campers and RV's; it's a great standard to reference. AND... the ABYC is based off of the NEC. BUT... the answer to your question get Codes vs Standards... which is a whole different ballgame. That being said; I reference both the ABYC (Electrical Standard) and the NEC (Electrical Code) (edit)...and in a lot of cases... the ABYC is more strict than the NEC. If you want to dive into that; it's the reason why romex solid core 12/2 is still used in RV's but the ABYC forbids solid core wire in marine applications. The vibrations can cause those wires to break.

[@TerrydeAlaska]

@@EXPLORISTlife Thanks for the explanation. I do think that to use the ABYC is a bit too strict for RV applications, like tinned wire and galvanic isolators to name a few, the environment is just more complicated and you can't just pull over and get out. Thanks for all the great things you do for the community.

[@EXPLORISTlife]

@@TerrydeAlaska Worth noting that I'm not asking people to follow the ABYC to a tee. Simply used as a resource article.

[@EXPLORISTlife]

@@TerrydeAlaska Also... I'm not going to be doing inspections on people's work, so ultimately everybody can do whatever they want. Lol

[@ModernSurvivalSense]

Wait a sec... if the fuse is to protect the wire... why are you sizing it to the size of the load and not the wire?

[@csteutterman]

I think I'm missing something obvious here, but I don't understand why the max fuse size just has to be less than 150% of the max amps of the wire instead of 100%. For example, if the max amps of a wire was 100 and you added a 140 amp fuse to stay under the 150% max fuse size, wouldn't a load of 120 amps be bad for the wire since it's over the max amps of the wire, yet it still wouldn't be protected by a fuse?

[@EXPLORISTlife]

That 150% rule is directly from ABYC E.11 (b) & (c) and was written by engineers and electricians with years and years of schooling and experience. I understand what you're saying, but when a code or standard is written...I'm going to teach it instead of trying to make up my own rules based on what 'seems to be right'.

[@wjohninoz]

There needs to be some amount of allowances for current spikes. Eg when you power up a load they often have in-rush current. 150% allows for in-rush current and not blowing fuses constantly.

[@burkayozcelik3019]

Am I the only one who didn't understand anything?

[@kevinkukla3948]

yes.

[@ML-hf6ii]

Yes

[@wiegehtsdenn1234]

Your diagrams are not free... they cost 9.99!

[@EXPLORISTlife]

The standard resolutions diagrams are indeed free at www.explorist.life/solarwiringdiagrams If you want the high resolution version to zoom in on or to print off at up to 24"x36" 300dpi, those do indeed cost $10. I hope this helps clear up your confusion. 🙂