Fault protection circuit
I'll provide some general advice for generic home applications.

First, since your battery is a long distance away from the load, I would wire in a fuse right off the positive battery terminal.  A simple, cheap inline fuse holder would suffice.  That way, if your cable gets damaged and the conductors touch, your battery will be saved.  If you do anything in this response, put in the fuse first.

For the load side, you have to think of the scenarios you want to guard against, and design to that.  Scenarios include:


Electrostatic discharge (ESD).  This is likely, although to what kV range is your choosing.  Often a simple capacitor (1 nF - 100 nF ish) will suffice for typical ESD hits when placed right on the positive and negative inputs to your circuit, and you could use ESD-type diodes to further strengthen it if you are concerned about larger strikes.
Reverse voltage, for when someone might connect the battery backwards.  There are various ways of accomplishing this, mostly driven by whether you are doing a PCB design or not.
Over voltage.  This may or may not be a concern, depending on what you are doing.  Just note that if you connect a battery charger to the battery, the voltage will go up.  You may want to design for a maximum voltage in the 32 - 36 V range.  But there are many power supplies (wall transformer and PCB-based) that can handle this.  If your circuit is fine with 32 - 36 V input, then I would suggest that no further protection is necessary.
High frequency protection.  This may either be very important or not at all, depending on your application.  In most casual applications, I would say nothing is required.  But if you have concerns (say, if you are doing radio or audio work), you need to identify the bandwidth you are concerned about and design a filter that targets that bandwidth and treats it by the desired amount.  There are many filter designs available out there.  But I wouldn't bother unless you have a specific concern due to your application.
There was mention of lightning.  You'll probably get an induced effect over your cable run when lightning occurs in the region.  Again, your application will determine whether this is a problem or not.  For example, if this is an audio application, you'll probably hear the speaker chirp when lightning is around.  Grounding techniques are your friend here if you think this will be a problem.
Immunity. This comes in conducted and radiated effects. In a residential setting, radiated transients should be reduced (industrial is another story), although your cable will likely pick stuff up like the antenna it is and turn it into conducted high frequency noise that goes into your load device - in which case it becomes a high frequency noise issue as discussed above.  For a typical home/hobby project, I wouldn't worry.  But if you want to go to market with this, you'll need to think about it.


If you're willing to share more information about your application, the community could target their advice better.  If I was doing a general hobbyist-level project without special needs (i.e., audio or radio) and not going to market, I'd just leave it at:


Fuse at the battery.
ESD capacitor on the input.
Either an input diode or transistor for reverse polarity (likely with hand-wired batteries).
Power supply rated for 8 - 36 V input.