Fuse protection

[David HK]

The last part of the jigsaw to go into my system is fuse protection.

I have searched the board and see that quite a few people use automotive fuses that are good up to 30 amps or therebouts.

People have commented about fuse protection for batteries and others have discussed using fuses on each individual LVD lines.

I need to do both of the foregoing and also include the photo voltaic panel array.

My plan - subject to your comments - is to use automotive fuses simply for convenience. However, the question is how to mount them. I do not really want a fuse box out of a motor vehicle because they're usually large, ugly and difficult to work with.

Has nyone on the forum built their own mounting and holding device for auto fuses, and, if so, could you put up a photgraph showing how its done.

All comments welcome.

David

Hong Kong

[Rover]

It actually depends more on the current requirements for the loads.

Anything under 15 amps I use a marine fuse panel with panel mount glass fuse holders, alot of times these also have switches for each fuse as well.

Anything over that I use AGU or ANL type fuses, in inline holders mounted on the inside of electrical box.

[ghurd]

For small systems and small loads, I like the marine fuse blocks too.

Cabelas.com has better photographs.  Item IK-011915 and IK-019671.

The types with the negative bus bar is more handy.

The solar can run into the system 'backwards' through one of the fuses in the block,

shown below with the small red wire.

Most of what I do has a few small loads where the 50-90W solar panels and battery are located.

The primary use is to charge batteries for use in other locations, which explains the clamps.

G-

[richhagen]

Hi Dave, I hope that all is well in your part of the World.  If your system is higher than 12 volts, I would be reluctant to use automotive fuses as they are not designed to quench arcs at higher voltages.  There are DC fuses and circuit breakers for higher dc voltages but they are a bit more pricey. For tiny 12VDC systems, I have simply used inline fuse holders attached at the battery.  For me, as a simple rule, I try to fuse all power sources, panels, and batteries, as near to the power source as possible just in case of line shorts or mischief, although the tiny 12V systems I just installed in the Philippines were fused only at the battery.  Rich

[Capt Slog]

I used something like these...

http://uk.rs-online.com/web/search/searchBrowseAction.html?method=getProduct&R=6661608

and built them into a little project box.  I realise that they are not in the amp capacity that you wanted, but they were to protect the low current lighting circuits connected to my RE power.

Perhaps you need to have two types?  Large heavy duty stuff for the incoming power, and  

 another design for the outputs?

.

[Shadow]

 I use this type throughout my system. Not sure what youre budget is but these work good.

 I have one between the battery bank and inverter rated at 80 amps (48 volt battery bank, 3600 watt inverter) and when we get close to capacity on the inverter, (microwave running, dishwasher, hair dryer, curling iron.... all running at once) this fuse trips everytime! the inverter never shuts down from being over loaded.

We do have to run outside to the battery shed and reset it but thats ok.

You may search around and find them cheaper.

http://www.prontohome.com/compare/blue-sea-systems-7114-80a-11500450982

[wooferhound]

You have probaby seen this from me before, I think you know that I have a 12v system and use the power directly without an inverter. I use inline fuses throughout my system because everything is so cheap. The Fuse Blocks come in multiples of 4 and 6 making plus the fuses come in infinate current ratings making things very versital for projects. I guess the biggest limitation is the maximum possable current ratings if about 15 amps, I think I've seene some rated at 20 amps.

The battery must be fused as close to the battery as possible. If something were to short-out there would be a huge wiring fire as the battery will be capable of delivering over 1000 amps into a short circuit so I have a fusebox at-the-battery to fuse everything going In & Out of the battery to prevent shorts from causing fires. Here is how I do it...

http://www.fieldlines.com/story/2008/6/7/21233/94327

I have 9ga wire coming from the Battery Fusebox 110 feet to my computer area where I use the power. This wire is good for over 40 amps but I have a 20 amp fuse on it at the battery. If my system expands, I will be increasing the fuse for this long wire run. Under my computer desk is a second fused distribution panel with capacitors to help prevent power surges. Most of the wiring past this point is 18ga (7 amps) & 16ga (10 amps) wire, so I must provide fused outputs to these smaller wire runs. Right now I have four 5 amp fuses in this box. If I didn't fuse this smaller wire, then they would be protected by the Large Fuse in the Battery Fusebox making another fire hazard.

http://www.fieldlines.com/story/2009/3/18/232910/066

One of our other members (richhagen) made this Fused Diode Isolated solar input panel with inline fuses here...

http://www.fieldlines.com/story/2004/12/12/232315/76

[(unknown)]

I am going to try this.

[independent]

Wooferhound is right, fuse as close to the battery. Did some research into this a year or so ago. This is what i found out. Someone will correct me no doubt if it is in doubt.

It comes down to whether you have an earthed system or not. From what i read if you don't then most properly a fuse on neg return and pos is a good solution. I do this and only bother fusing the battery and appliances and not solar. Only use solar and these handle a short circuit fine (if that was to occur) and figure a high resistance connection is worse by far that any limited current device such as solar. My system is 12v.

You may find that your local regulations might require an earthing situation too.

I use the larger spade fuses on the battery. Also on smaller devices as well. Both double fused. Don't like the glass fuses as you can't easily see when they have blown close to the sides which they often do.

[Ungrounded Lightning Rod]

In addition to fusing the load circuits, consider using a fusible link at the battery itself.  Think "wire that's also a fuse intended for dead-shorts and designed not to catch fire if it "blows".

Replacement fusible links in a number of capacities should be available at automotive and marine supply stores.

[David HK]

Thanks chaps,

Your comments are first class and I shall err on the side of marine fuses etc.

Price never comes into my designs, I always prefer material quality and those things that make good sense.

David in HK

[Rover]

You can a bunch of them on ebay fairly indexpensive. I'd look for those that actually have specs.

If price really doesn't matter, you could go with marine breakers and panels... but the cost can get ya .. around 20$ per breaker.. cheapest I've found. I can't justify the cost.. over fuses.

If you need to reset a breaker that often that the cost works out, something seriously wrong to start with

[richhagen]

That box from the post of mine that you referenced is still up on my roof now, more than five years later.  I have a string of panels attached to all of the fuse connections now.  I replaced one fuse that I blew a year or so back as the fuse was marginal for the panels current rating, but other than that there have been no issues.  Rich

[harrie]

Thanks for the link Shadow, been needing some safty on my 48 volt system!!