Fuses in Wires.... Yes... No....

YodaRules

Ordered two 150W Renogy Panels, 30A PWM Wanderer Controller, MC4 connectors, 8' of 10awg wire (battery to controller) and 30' of 10awg wire for controller to panels. Now, I see in the image attached (hope I did this correctly) there are 2 fuses in the wire...... Have no idea about these fuses or how to get them attach to the wiring (or size of fuse needed).  Help is much appreciated...

Patsy

DConlyGuy

i used these http://www.ebay.com/itm/231881097158?_trksid=p2060353.m2749.l2649&ssPageName=STRK:MEBIDX:IT and you can see in the picture how i used them since my controller is a 35 amp i went little less and just used 30 amp fuses

littleharbor2

Better yet you can use inexpensive breakers and add the ability to easily shut down your system for service. Square D QO and QOU breakers are rated for low voltage DC. Midnight Solar breakers should be used on higher voltage systems, up to 300 volts.

YodaRules

I see your fuse.... my question is how to get the fuse holder on the tray cable wire?  Do I simply insert it at the end of my 8' cable then run another new wire piece to my controller? Do the wires touch each other?  You can see my "newbieness" in this.....

BB.

Remember that fuses/breakers primary job is to protect the wiring from overheating... What is the AWG of the wiring? Fuses/buses and breakers (and the wiring) should not be undersized when compared with loads.

For example, if you want to support a 25 amp load, then multiply x1.25 (NEC derating factor for fuses and wiring)=31.25 amps minimum for branch circuit wiring. US protective rated devices will (eventually) trip when operated at rated current.

Also, fuses can be expensive--You don't want to pop them with normal loads. Undersized fuses+breakers do not really "protect" the equipment and loads and under-sizing protective devices just make your system a bit "unreliable" (false trips, power "fails" when you are on a trip, leaves spouse in darkness, etc.).

-Bill

YodaRules

My wiring is 10AWG........... I am lost in this...... sorry!

basewindow

Are you asking 'How do you physically connect the fuses to the wire or cable?"

If so it depends what type of fuses or breakers you're going to use.

You can either use two separate cables or cut the one you have in half as long as its long enough.
Many breakers simply require you to insert the bare end of the cable into one end then you secure it in by tightening the little clamp with a screw driver or similar. Probably much the same way you connect your cable or wire to your Solar Charge controller. Same with the other end.

Fuses generally need a fuse holder, which are usually purchased separately or may come with your fuse. How you connect the fuse holder to the wire can be many and varied. Some fuse holders have a screw and clamp system like the breakers. Others may just require crimping (with a crimping tool) with various end connectors (rings or spades etc) or simply the bare wire twisted and joined with standard wire connectors. (An plastic insulated screw and clamp)

As to where you physically put them, depends on many things but its generally best to put the one connected to the battery closest to the battery terminal but somewhere easily accessible.

Same with the inverter etc. In small one panel systems the one from the solar panel is not so important and sometimes not even included, but recommended so the panel can be isolated from the controller if need be.

As to the size etc it will depend on the current draw. They are usually rated in Amps, for example a 30A rated fuse will usually pop when more than 30a is going through it. (and I'm being very general here.) Each of these fuses or breakers has to be sized to the current draw on that particular part of the solar system. For example the fuse or breaker between the solar panel and control woud be rated to slightly more current (amps) that your panel(s) produces (Isc). I think the diagram you attached says Isc x 1.2. And not more than the rated current of your charge controller as well. Each individuall cable needs to be rated to also carry that current. The Isc of your solar panel can be found on the back on the information panel. In general for a single panel low wattage panels these cables are relatively small and so are the fuses.

The one between the battery and controller is usually rated the same way or simply around the maximum of your Charge Controller and cable. Again being very general Controller rated at 15amps, a fuse or breaker rated at the same along with a cable or wire rated to carry the same.

The one between the inverter needs to be rated to the inverter power rating and will generally be much larger along with heavier thicker cables etc.

The fuses are there to protect the components of the solar system from being destroyed or damaged in the event something goes wrong and also to prevent cables, wires or components melting or catching fire in the event something goes wrong. The fuse pops or the breaker, breaks the current before that event can occur. (hopefully)

Remember I'm being very general here just to give you a simple idea. Other posts here explain how to calculate what you need depending on the specifications your system and its components. .

BB.

There are some standards--NEC (National Electric Code) is the most conservative:

https://lugsdirect.com/WireCurrentAmpacitiesNEC-Table-301-16.htm

10 AWG copper wire is rated for ~30-40 amps maximum (in conduit at room temperature). There is a footnote that says 10 AWG is always limited to 30 amperes maximum (I could never figure out why NEC derates their "deratings" for smaller AWG cable).

The ABYC (Marine) standard is not as conservative:

http://www.acbsphl.org/Tips_and_hints/ABYC_Wiring.htm

10 AWG is good for 51 to 60 amps.

So--10 AWG and 30 amp fuse/breaker is perfectly OK. Note that the NEC (and typical fuses/breakers) should be operated to a maximum of 85% (note 1/0.85 = 1.25x):

• 30 amps * 0.85 NEC derating = 25.5 Amperes maximum continuous current

I see your fuse.... my question is how to get the fuse holder on the tray cable wire?  Do I simply insert it at the end of my 8' cable then run another new wire piece to my controller? Do the wires touch each other?

Basically, any fuse or circuit breaker--You "cut the wire" and insert the fuse/breaker in between the wire ends. All current flows through the protective device. If there is too much current, the devices opens (turns off the current flow)--Just like a switch.

The actual method of wiring depends on the holder you choose. A good reason to use "house wiring" is that most fuse and circuit breaker wire connections "work better" with solid or coarse stranded copper wire... The very fine stranded wire usually does not clamp as reliably.

Many people with use fuses+holders for their off grid power systems... However, fuses+holders can be pretty expensive (breakers may not be much more--especially if you buy some spare fuses to keep on the shelf). Also, circuit breakers can be used for a switch to turn off the loads and charge controllers (and used on larger solar arrays). The breakers are handy for shutting down the system for the winter and/or debugging. And save you from having to install a fuse+holder+switch for the same function. Note, many fuse holders are not designed to have the fuses "removed under load" (there are some "touch safe" fuse holders that will arc and catch fire if the fuse is disconnected under load).

Here is one video that shows how to crimp a ring lug onto wiring (note--A good crimp should never be soldered--The crimp is "better" than a soldered or soldered+crimped connection).

https://www.youtube.com/watch?v=UXij6hXBUZs

This video shows a fuse holder that uses cut cable ends instead.

https://www.youtube.com/watch?v=BxViIYceT0c

Note the fuse/breaker should be located close to the battery (1.5 to 2 foot maximum is typical). You want to fuse to protect the wiring against short circuits.

Poster 2manytoys has on his web site (about 1/2 down on the right) a lot of photographs of his solar install--From his first installation and as he made upgrades and redesigns (and lots of DYI solutions he did too):

http://2manytoyz.com/

If you have any more questions, please ask. Everyone starts at the beginning.

-Bill