12VDC Problems

[azmaddog]

Hello to all,
I'm having an interesting problem with the 12V side of things. Was trying to update an under hood fuse panel from the old glass Buss fuses to the much easier to find ATC fuses. While replacing the fuse blocks, I found a large round inline fuse holder that had a short in one end. Due to age and the Arizona heat, when I tried to open the fuse holder it broke into lots of little pieces. It didn't harm the fuse, which is probably the best thing about it. But now I can't seem to find a replacement part. I think that part of this is due to Buss fuses company having been bought up by EATON. I've tried contacting them and after an email telling me that they were transferring the issue to the 'Bussman' side of the company, there has been no other communication from them. Yes, I tried getting ahold of them again, but still no reply for over a month.
So here's my problem. The inline fuse is a 10.3mm X 57.15mm Buss Class G SC-40 Time Delay 300VAC or less to Ground; Current Limiting Interrupting Rating 100,000Amp RMS a.c.; Partial part number of _G83-03 U.L. Listed Fuse. It appears to be factory original from Fleetwood on my '87 Pace Arrow Y27 motorhome. It is definitely connected to the house 12VDC converter and possibly to the alternator on the 454CID engine. I was having some issues with the alternator not charging, now I suspect that it's all tied in with this fuse. I debated just changing it out to an ANL type, but can't find anything with the correct time delay factor of the original fuse. BTW, original fuse is still good, but I can't seem to locate anyone willing to sell me just 1 fuse holder. And I won't buy a case of them for $300+ dollars.
Any helpful ideas or information would be greatly appreciated.

[Soppy]

Another option may be to replace the fuse with a self resetting 40 amp circuit breaker.The circuit breaker will have a time delay function similar to a time delay fuse and are way easier and cheaper to source.

[Argosy]

https://spadepot.com/products/fuse-h...class-g-bx9421


Did it look like that one?

[azmaddog]

Nope. Looked just like an oversized inline fuse holder for a glass fuse that used a screw on or bayonet style fitting on one end. About 4-4.5 inches long, black, with red 6 gauge on one end and red 8 gauge on the other end.

[azmaddog]

Couldn't find one that had enough amp rating and delay factor in DC. Found a couple of ones for AC, but they were only in Europe. So I haven't seen anything over here. BTW , the breakers from Europe were all Siemens for 250VAC @ 50Htz.

[Argosy]

I've never seen a Class G fuse in an inline fuse holder. They actually are different lengths for different current ratings so that's another problem for you.


Why not use an ATC fuse? You could put it in the fuse block you're setting up as long as it's not over the current rating or get an inline holder for it. You're getting rid of the AGC fuses because ATC is more common, the Class G is even more rare in automotive applications.

[YC1]

I would love to see a picture of it.

https://www.walmart.com/ip/30Amp-480...ce=chatgpt.com


https://www.amazon.com/Bussmann-Powe...ce=chatgpt.com

There are many much more modern devices available unless you are just wanting to stick with some sort of original looking setup.

It appears to be a "slow blow" fuse. That is, the initial inrush of current will not blow the fuse if it exceeds the rating for a few seconds.

[azmaddog]

Welcome to the club on that. It definitely threw me for a loop when I got ahold of the fuse. Not to mention that I just rechecked the EATON/Bussmann site and they no longer make this particular fuse. Trouble with ATC/ANL delay fuses is the delay factor issue. According to the graph buried in the EATON specs side, this fuse will handle a comfortable 40A all day long. But the key is that it will handle 600A for a minimum of 12 seconds before blowing. I suspect that besides being tied into the charging circuits, it's also supposed to handle the starting load in this beast. I probably should have mentioned that this has a Group 31 1000CCA /1240CA battery for the engine, and 2 deep cycle Group 31 deep cycle house batteries with a momentary boost crossover rated at 400A. Engine is a Heavy Duty Emissions 454CID that uses a 10M 9-tooth heavy diesel engine starter. I'm pretty sure that the batteries aren't original spec, but it seems to need that monster amount of cranking power to spin it up to starting speed. Only modification to the engine that I've found was an add-on dual-fuel conversion to the original factory Rochester QuadraJet carb. I've pulled most of that off already, so it shouldn't be altering the starting factor. Did try putting a much smaller battery in it rated at 700CCA and it didn't want to start without the boost from the house batteries. Not sure if this was due to the short in the inline fuse holder or not, but it's got me wondering.

[azmaddog]

Not trying to stick with factory looks, just want something similar. Holder is in about 50 pieces, but I'll try to post a pic of the fuse.

[azmaddog]

Hopefully these are clear enough.

[YC1]

Not going to be in the starting circuit unless it is just to supply power to a starter solenoid.

With the size of the wiring being the limiting factor, a 50 amp breaker should work. I provided the links, did they not take you to a supplier for the fuse you want?

[azmaddog]

The only links that show are for a Class G fuse and the side-mount holder for it. And the fuse in your link is a larger capacity than the one I actually have. The only circuit breakers that I found prior to this are all European house panel type breakers from Siemens. I don't want to have to buy a special type of electrical box and breaker set. I'm hoping that someone who's more familiar with the 12VDC than I am will know of an automotive type solution that will do the same job. Personally, I don't like mixing A/C type parts for D/C type circuits. Probably picked it up from the person that taught me electricity in the first place. But he's been gone since '88, so I can't ask him anymore. And they don't make Master Electricians like him anymore either.

[Rotten-Dog]

I am not sure that fuse is correct for its use. A lot of Motorhomes tend to be hand crafted where things change quickly and changes are made on the line. They may have needed a 40A fuse for something and had this lying around or could get it from distribution right away. Unless you are running laser cannons on the front of the RV, (I've wanted these), there is nothing that requires 100,000A interrupting capacity at 480VAC or 10,000A at 300VDC. I think the best course of action is to find out what this behemoth feeds and then we can engineer the correct fuse or breaker. I've attached a couple of data sheets for what you have there.

Have you traced the wires, and can you tell us what this fuse feeds?

[azmaddog]

Well, I guess I'm not the only one who goes digging up odd information. And while I would wish for the same laser cannons at times, I definitely don't have those. As for tracing the wires, this fuse holder exited and then reentered the same 1" diameter wire loom about 18" below the fuse panel under the hood. That wire loom drops down under a wood/steel frame panel and then goes up into the engine compartment with what looks like 3 additional 1" wire loom as well as a batch of loose wires taped to the outside of several of the looms. To actually be able to trace it, I'm probably going to have to borrow (or buy) a tone tracer unit. I've looked through the wiring diagrams that I have for the chassis, but its not showing anything similar. And I know that the house charging unit is definitely tied in there as well. I have to admit that the amp interrupt capacity is one of the things that threw me. I might expect to see one that high for the coil output, but most definitely not on a regular circuit. So if I get a time delay ANL, you think that would work?