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kartvines · 01-07-2011, 06:48 AM

OK, well I tried tracing the wires to determine what they powered and that failed

so I need to just move forward with adding fuses to power up the circuits, I removed most of the wires that was going directly onto the battery post and fused them separately.

I have no idea what circuit are what, so that mean I do not know what size fuse I need to install to energize that circuit.

Can anyone advise me the methods of determining the required fuse size? Guess I could start out small and work my way up until the fuse hold , but that could jeopardize that circuit, and can get costly.

IC2 · 01-07-2011, 07:26 AM

Quote:

Originally Posted by kartvines

OK, well I tried tracing the wires to determine what they powered and that failed

so I need to just move forward with adding fuses to power up the circuits, I removed most of the wires that was going directly onto the battery post and fused them separately.

I have no idea what circuit are what, so that mean I do not know what size fuse I need to install to energize that circuit.

Can anyone advise me the methods of determining the required fuse size? Guess I could start out small and work my way up until the fuse hold , but that could jeopardize that circuit, and can get costly.

I believe I know what you are asking - and it appears that you have some circuits in a TT that you need to power up. I think we can help, but do need to know what kind of equipment you are adding. Here's a place to start for the kinds of fuses: Fuse (electrical) - Wikipedia, the free encyclopedia

There are several different types of fuses plus would like to know what kind of fuse block are you using. For instance, are you just doing lights - that depends on the wattage. Will you be using Bosch type relays? These are handy for running circuits. Here's some discussion on that: Single Pole Double Throw (SPDT), Single Pole Single Throw (SPST) Automotive Relays

These are kinda general questions based on what you posted, but - for sure someone here can help if my little amount knowledge wont

bldrbob · 01-07-2011, 07:49 AM

A good place to start would be to determine the wire size and not exceed the amperage rating.As you connect check what works and adjust fuse size according to the rating on the item making sure you don't exceed the wire rating.
BOB

kartvines · 01-07-2011, 09:10 AM

Thank you for the feedback so far, I will review it to see if it will work for me. In order to insure we are all on the same page I have attached a link to my blog that show the ATO 10 gang/circuit fuse panel I am using [photo # 5 within the blog text] in the case we are not taking apple to apple, please find that link below: I am not adding any new equipment, just tying in what was preexisting.

http://1983pacearrowmotorhomerestoration.blogspot.com/2010/12/installation-battery-disconnect-switch.html

Over the next week end I will be powering up these fuse block and
re-energizing all of the circuits. Again I wish I knew what each circuit/wire powered, but due to lack of color coding and wiring diagram I have no clue, I also think that most of these circuits/wires may be fused in another location, these panel will merely be a backup circuit easier to get to, to replace fuses, instead of having to climb under the dash through the wire maze trying to locate a blown fuse.

Once I get them energized I hope to be able to then locate what they power and then label each circuit with a name, and I guess the easier way to perform this task is to power everything up and then pull a fuse to see what goes off.

I plan on using 8 guage wire running from each panel to the battery, assuming this will be heavy enough to pull the power needed, each of the wires connected to these panel are of a lesser of a gauge wire. Does anyone think that the 8 gauge wire is not heavy enough, do I need to go with a 4 gauge wire instead? I think that would be too heavy to be able to attach to the lug on the panel. Once I get everything working correctly I will replace all of the fuses with he ones that will light up once blown to make it very easy to I.D.

Feedback is still most welcomed. being I am sure there are many more skilled folks out there than I.

kartvines · 01-07-2011, 09:29 AM

Quote:

Originally Posted by bldrbob

A good place to start would be to determine the wire size and not exceed the amperage rating.As you connect check what works and adjust fuse size according to the rating on the item making sure you don't exceed the wire rating.
BOB

Is there a standard that will determine the maximum voltage/amp a wired can exceed?

So let say a 20 ga wire can not exceed *.* so the fuse must be below that standard? Is this a safe and sang manner to determine the size of a fuse needed to protect a circuit? That of course is assuming the PO used the proper size wire when installing everything, overall the majority of the wires used were the same color and gauge.

Maybe I should have left well enough alone and no make the effort to clean it up.

IC2 · 01-07-2011, 11:00 AM

Quote:

Originally Posted by kartvines

Is there a standard that will determine the maximum voltage/amp a wired can exceed?

So let say a 20 ga wire can not exceed *.* so the fuse must be below that standard? Is this a safe and sang manner to determine the size of a fuse needed to protect a circuit? That of course is assuming the PO used the proper size wire when installing everything, overall the majority of the wires used were the same color and gauge.

Maybe I should have left well enough alone and no make the effort to clean it up.

Here's an ampacity chart; Wire Chart

I would NOT use 20ga wire for anything on a vehicle - 18 up to 12, depending on the load with the main feed at least 6 or 8(min). Most battery leads are at least 4ga and if it's a MH with batteries a distance away, these can get really heavy, like 0 or more

InPursuit · 01-07-2011, 11:11 AM

Quote:

Originally Posted by kartvines

I plan on using 8 guage wire running from each panel to the battery,

why? I mean were ANY of them 8 gauge before?

Quote:

assuming this will be heavy enough to pull the power needed, each of the wires connected to these panel are of a lesser of a gauge wire. Does anyone think that the 8 gauge wire is not heavy enough, do I need to go with a 4 gauge wire instead?

8ga is likely an expensive overkill let alone 4ga.

In an case... this is where amperage draw comes into play.
The actual amperage drawn based on what you (eventually) determine is on the circuit

Quote:

Once I get everything working correctly I will replace all of the fuses with he ones that will light up once blown to make it very easy to I.D.

I'd suggest that you start here.
Fuses are cheap. Buy a bunch of 5amp and 10amp to use for this investigating. And then move up to 15amp as needed.

Most of the existing wire will be 12gage but few circuits should need the full load (20amp) fuse that 12ga will carry.

A few may/will need more than a 15amp but not many.

Retired and Happy · 01-07-2011, 01:26 PM

Did I miss something? What are you doing? Why? What is your expected result?

kartvines · 01-07-2011, 03:00 PM

Quote:

Originally Posted by InPursuit

why? I mean were ANY of them 8 gauge before?

8ga is likely an expensive overkill let alone 4ga.

In an case... this is where amperage draw comes into play.
The actual amperage drawn based on what you (eventually) determine is on the circuit

I'd suggest that you start here.
Fuses are cheap. Buy a bunch of 5amp and 10amp to use for this investigating. And then move up to 15amp as needed.

Most of the existing wire will be 12gage but few circuits should need the full load (20amp) fuse that 12ga will carry.

A few may/will need more than a 15amp but not many.

I only used 20ga as an example., I am using none of the , most of the wires are 12g and some 10g. I guess I could do the fuse blowing test, I am sure it would work, just waste a lot of fused, so once th fuses hold that that is the correct amp? I looked at the wire chart above and was not able to gather much from it. I went to 8ga to pull the amps from the fuse block to the battery post so it could pull the load without overheating. The distance form the block to the battery post is only approx 16"

bldrbob · 01-07-2011, 08:07 PM

You have to add up the total amps that might be drawn thru the fuseblock at the same time and size the feed accordingly. I think an ampmeter to see what the draw is on a line would be better than playing with changing fuses till they don't blow.
BOB

IC2 · 01-08-2011, 06:46 AM

Quote:

Originally Posted by kartvines

I only used 20ga as an example., I am using none of the , most of the wires are 12g and some 10g. I guess I could do the fuse blowing test, I am sure it would work, just waste a lot of fused, so once th fuses hold that that is the correct amp? I looked at the wire chart above and was not able to gather much from it. I went to 8ga to pull the amps from the fuse block to the battery post so it could pull the load without overheating. The distance form the block to the battery post is only approx 16"

OK - we've gone in several different directions and hopefully answered your questions. I think we can probably do more to help you if we knew exactly what you are doing. I doubt that the OEM wiring that you are doing is 12-10 gauge as it is overkill for most 12v circuits. Plus darned expensive if not required.

Let us know if we can help.

Dave W

TQ60 · 01-08-2011, 07:16 PM

The fuses in the block are designed to protect THE WIRE, not the device connected to the wire.

What thins means is if the wire shorts to ground, or there is a load that exceeds the capacity of the wire, then the fuse blows.

So others have provided a link to data reflecting thes, but simple terms, 12 ga is 20 amps, 14 ga is 15 amps.

There are other things to consider with low voltage DC circuits, one is voltage drop across the wire.

The low 12 volt power means that there are higher current draws than for things that operate at 120 VAC, so the length of wire also makes a difference.

The feeder between the battery and the fuse panel needs to be as large as reasonable to reduce any voltage losses.

If the distance is short it is not as critical but if it is over a few feet then it should be larger.

A battery cable from the parts house can be purchased reasonably that can be used for this, they have some that are very long and would allow the fuse panel to be mounted in a better place away from the battery.

Since you are working on your wiring be sure that all connections are clean, the grounds are good and the circuits properly loaded.

If you place the proper size fuse for the WIRE and it blows when say all of the lights are turned on, then you have too many lights on the wire and the circuit needs to be redesigned, lights need to bel placed on another circuit or the wire is too small.

Never place a fuse rated above the rating of the wire into service.

Some have used 1/4 in bolts...we call them a 20 amp never blow...

Electrical grease can be used to reduce problems as well.