Do I need a fuse box if using a portable power station?

[nackler]

I have been planning to run all the wiring to a cupboard in my galley where ill just hook all the dc together and all the ac together into plugs and plug them into a portable power station. Solar too.

No fuses, no inverter, no power meters, all just floating with no ground.


1, how bad is this?
2, should i have fuses anyway (lights vs fan vs cigarrette lighter sockets) or would this be redundant?

 

[Pmullen503]

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[Pmullen503]

I have been planning to run all the wiring to a cupboard in my galley where ill just hook all the dc together and all the ac together into plugs and plug them into a portable power station. Solar too.

No fuses, no inverter, no power meters, all just floating with no ground.


1, how bad is this?
2, should i have fuses anyway (lights vs fan vs cigarrette lighter sockets) or would this be redundant?

That's insane.

AC and DC must be separate. There are neutral wires and there are ground wires and they aren't strictly the same. The DC neutral wire is often called a ground. The AC ground wire is just that, it ultimately goes to a stake in the ground to safely deal with stray current.

Fuses are there to protect the wiring from causing a fire if there is a short. So unless your power station has circuit breakers built in (and your wiring is sized so the power station's breakers will trip before the wiring burns) you MUST have someway to protect against shorts.

Because you (or someone else) may someday hook an unfused power source into your system, you should at the very least have a main fuse between the power source and the rest of the trailer's wiring.

 

[nackler]

Thanks. I guess I should have clarified that by no ground I meant I would not ground to the trailer, but all the grounds would go back to the power station.

In effect, all the AC outlets would be as if they were extension cords back to the power station and the lights and DC outlets would just be a big DC appliance.

 

[nackler]

Thanks for explaining what fuses are for. I guess that for wires hidden in walls the danger of overloading is that damage or fire could be hidden from view. A large fuse (for DC) and a breaker (for AC) seem like a good idea.

 

[GTS225-TNT]

Mr. Nackler; What if, 8 years after you've built this, one of your AC "hot" wires rubs through and grounds to your chassis/frame? (This is, after all, a rolling earthquake, and every bit of it will see vibrations, bouncing, and all manner of road hazards.)
That abraded hot lead is now charging your chassis at 120 VAC, with no complete circuit to keep it from hurting anyone. (Insulated by rubber tires.) You've plugged into "shore power", and your frame is charged, now what do you suppose will happen if/when you place a stabilization jack under that frame, and you touch it while also contacting the earth?

Now.....you also have no choice but to ground your trailer's chassis to your towing vehicle's ground, through your tow ball and coupler, if only temporarily, even if you do have dedicated wires in your circuit..

I implore you to at least bond your trailer's chassis to the AC grounding system. Grounding in alternating current systems is for human safety, and should NEVER be ignored or forgotten.

Roger

 

[Pmullen503]

Thanks. I guess I should have clarified that by no ground I meant I would not ground to the trailer, but all the grounds would go back to the power station.

In effect, all the AC outlets would be as if they were extension cords back to the power station and the lights and DC outlets would just be a big DC appliance.

Ah, I misunderstood. The two systems need to be isolated from each other as AC and DC don't mix. So what you describe would work.

In my own trailers, I have the 12v cabin system NOT connected to chassis. I prefer to keep the trailer lights connected only to the vehicle's electrical system. Because the two 12V systems are completely separate, a fault in one can't affect the other.

If I did have an 120V AC system, I'd use GFIC breaker sockets as well as (at minimum) a main fuse. Cheap insurance.

 

[Tony Latham]

A large fuse (for DC) and a breaker (for AC) seem like a good idea.

The smaller the wire, the smaller the fuse. If you install a large (20 amp?) fuse, it won't protect anything.

Part 2: Select a Fuse and Fuse Holder For Your DC Product Installation - Blue Sea Systems

Tony

 

[pchast]

Its just good practice... the fuses on your power station will do nothing to protect any wiring or fixtures.

 

[philpom]

I'd consider doing as much 12v throughout as possible and placing fuses at each appliance. Also, pass any AC through a breaker, GFCI is great.

I use 12v for everything and am set up that way with a main breaker behind it all. For AC I do have a 12" pig tail that goes inside, no chance of that grounding out. Safety is paramount.

 

[nackler]

Thanks all. I had in my head that a power station would eliminate all that but I see now it wont. Ill include a DC fuse panel, and an AC breaker, and an inline GFCI for AC.

My trailer running lights will ground to the trailer frame so Im not sure about grounding anything else to the frame. When on shore power of course i would be grounded to the shore but im not sure what else makes sense since we are on rubber tires.

 

[chopperwalker]

Like Roger said, if you don't ground the AC to the frame and there is a short, the rubber doesn't keep you safe. When you touch the frame in that scenario, you become the ground and the electricity passes through you. Connect the AC ground to your frame to avoid this.

 

[Grummy-TNT]

Which portable power station ? To my understanding, the 12v side on most if not all of them is restricted to a 12v Acc outlet, and they can only deliver 10A. So, for the most part, even if you did not have any fuses past the power station, the only issue would be if you had really thin wire somewhere that could go up in smoke.

That said, if I were using a power station, I would run that 12v output to a small fuse block with heavy enough wire for the 10A capability (wire size depends on distance), and smaller fuses for all the accessories you intend to run.

Those power stations to me are pretty limited for 12v stuff.... We hear all the time they won't even start a diesel heater.

 

[Grummy-TNT]

I wanted to comment on the concept of "where ill just hook all the dc together and all the ac together"... where we do all know that you are not speaking of actually CONNECTING them to each other, but mostly indicating it grouped in the same location.

But, you CAN get things really grouped together in the same cabinet, as long as things are divided properly. All industrial machines have both AC and DC in a single cabinet. You just have to make sure things can't cross up accidentally or by human error.

I have one power box, with AC on one side and DC on the other. In this cabinet, there is a fixed wall between the two sides, and the DC side is hinged so you can get at the wires behind.

In the cabinet is a 4 position rotary switch for Front, Rear or Inverter Source AC and Off. Marine style Blue Sea AC breakers make more sense in a conversion than a clumsy house panel.

 

[S. Heisley]

I haven't written because I wasn't certain what you meant by a portable power station. Are you writing about something like a Jackery?

Example: https://www.amazon.com/Jackery-Expl...8-2-spons&sp_csd=d2lkZ2V0TmFtZT1zcF9hdGY&th=1

People use the above types a lot without a fuse, so I think that's already built in to some of those units. Check with the company that you are buying from. Also, there are in-line fuses that you can add to the wires at the point just before they enter the actual battery unit, assuming your wires are in the walls. I don't like that type, but people manage with them. With electrical wiring, it's important that you are well versed in what you are doing, so I suggest you research and ask more than one source (more than just here).

 

[Tony Latham]

Here's an example of why you need a separate fuse box. A Fantastic fan needs a 4-amp fuse to protect the 16-gauge wire leads. If the power box has an 8-amp circuit breaker, that circuit isn't protected.

To me, it's a lot cheaper and more efficient to use a dedicated battery and fuse box. I keep an inverter in the tongue box, but I can't recall why. A 12-volt system has met our needs for the last 20 years of teardropping.

But, if you feel you need 120 volts, buy a proper inverter and hard-wire it in. You'll still be ahead financially. All batteries fail eventually, and when the one in the power box does, you throw the box away.

I'm running a 100 amp WattCycle lipo battery that costs $170. That's a lot cheaper than a power box with less amperage.

Tony

 

[nackler]

Thanks all for your replies. These "solar generators" are getting pretty cheap.

This is what my wiring might look like after weighing some of your feedback.

Does this look ok? Where do you all use bus bars instead of just splicing wires together?