Brakes - Emergency Breakaway Switch power wire has no fuse holder or fuse???

[John E Davies]

I have long been puzzled by this light purple colored wire that comes directly off the battery (hot) side of the 40 amp circuit breaker under the rear street side bed. It goes to the emergency BAW switch under the tongue, when that is pulled the batteries give full power to all four brakes by way of the blue wires, about 16 amps max for four brakes, (8 amps max for the Elite) depending on battery voltage.... according to The Internet.

I added an inline fuse holder there and installed a 20 amp fuse. Does anyone know why this wire was left unprotected? A factory mistake or some weird code reason?

 

Should I file a service request to alert them? It is dangerous to have an unprotected wire, it could cause a fire.

BTW I have measured the brake current and with AGM batteries I have never seen over 3.0 amps per magnet, I was going to install a 15 amp fuse but that might be too small, however with my new lithium batteries’s higher voltage, the current will be a little less.

Thanks.

John Davies

Spokane WA

 

Edited January 24, 2021 by John E Davies

[mossemi]

I’ll check mine tomorrow and let you know what I find.

Mossey

[bhncb]

This is an undesirable end result of using the house battery bank for the emergency breakaway source. It's either a RVIA or DOT requirement, maybe both, that the switch be directly connected to the battery.  Normally, with a dedicated breakaway battery, this isn't an issue because wire lengths are miniscule.

Common sense and best practices always overrule ambiguous requirements. I added a 25 amp type 2 auto reset breaker. 25 is the maximum ampacity of the 14 awg wiring so it won't burn up if it shorts or the switch fails, and high enough to eliminate any potential for tripping on initial surge. Whatever device you choose to use, make sure the interrupt capacity rating is adequate for your battery bank capacity.

[Landrover]

I would think it should not be fused.If the fuse popped and you needed the emergency break away it won’t do its job. It needs constant 12v power while hooked to the TV.

Edited January 24, 2021 by Landrover

[BackofBeyond]

Seems to be a quandary - Cautious folks would like to see the circuit protected - makes sense in most cases. However in this case - the safety factor of the BAS and its intended result overrides the "normal" fusing requirements. In some manner - the wire is a large amperage fuse - yes it will cause a little smoke and perhaps a flame. 

I would believe it is a requirement. Not fusing is less dangerous than any damage a run-away Oliver would represent. 

The resetting breaker is an interesting idea. 

I'll leave mine alone.

RB

[John E Davies]

1 hour ago, Landrover said:

I would think it should not be fused.If the fuse popped and you needed the emergency break away it won’t do its job. It needs constant 12v power while hooked to the TV.

It is pretty rare for a fuse in a good quality holder to just pop on its own, and if you check the BAW switch before each trip as you are supposed to, the system will be 100% fine. I think the code requirement is due to utility trailers with the battery and wires out in the open, where a cheap fuse would corrode due to water exposure (and neglect) and block the current flow. It wouldn’t pop. If Oliver wants to skip a fuse they should instead install a fusible link, inside at the breaker, which have been used forever in cars for applications where a fuse might not be ideal.

BTW, the big problem with the Ollie’s Progressive Dynamics fuse panel is not the fuses, but the way they are poorly held in place by junky , unsupported pot metal ears. With a good panel design like in your car they would be very trouble free.

John Davies

Spokane WA

Edited January 24, 2021 by John E Davies

[Maverick]

It is a DOT requirement to not fuse the wire leading to the break away switch.

[mjrendon]

Link to federal requirements (Cornell Law School)

Click on subpart C and then section 43 for specifics on breakaway 

Edited January 24, 2021 by mjrendon

[mossemi]

I have heard some reasonable ideas on the issue of fuses, circuit breakers and the way OTT installed the Fastway equipment.  So I thought I would look for some installation instructions and this is what I found.  It looks like all opinions aside, OTT is installing the product just as the manufacturer instructed.  And I’m good with that.

Mossey

[John E Davies]

2 hours ago, mjrendon said:

Link to federal requirements (Cornell Law School)

Click on subpart C and then section 43 for specifics on breakaway 

That was very useful. It does NOT have anything about fuses or no fuses.

(d) Breakaway braking requirements for trailers. Every trailer required to be equipped with  brakes shall have  brakes which apply automatically and immediately upon breakaway from the towing vehicle. With the  exception of  trailers having three or more axles, all brakes with which the  trailer is required to be equipped must be applied upon breakaway from the towing vehicle. The  brakes must remain in the applied position for at least 15 minutes.

So, I still think fusing that wire is a prudent idea. Unless there is some other section that discusses fuses?

John Davies

Spokane WA

[John E Davies]

2 hours ago, mossemi said:

I have heard some reasonable ideas on the issue of fuses, circuit breakers and the way OTT installed the Fastway equipment.  So I thought I would look for some installation instructions and this is what I found.  It looks like all opinions aside, OTT is installing the product just as the manufacturer instructed.  And I’m good with that.

That is a pretty darned basic diagram, and they don't show or even mention a fuse. An omission or a DOT rule? I rotated it so it is easier to read.

 

John Davies

Spokane WA

 

Edited January 24, 2021 by John E Davies

[mjrendon]

9 minutes ago, John E Davies said:

So, I still think fusing that wire is a prudent idea. Unless there is some other section that discusses fuses?

I don't disagree.  From a physics standpoint the wire is the fuse (as delivered).

I read though the other sections and did not find anything related to fusing, but I could have missed it.  I found online references to state laws with braking requirements but have not found those documents yet.

Edited January 24, 2021 by mjrendon

[John E Davies]

Well, I emailed Fastway asking how they decided to draw their diagram with no fuse. Maybe they can shed light on this. I hate the idea of the "wire being the fuse" because it could literally fail anywhere along is entire length, so it might damage other wires, and replacement could be problematic and labor intensive. You can easily string a new BAS wire, but fixing other burned ones, not so easy, especially if it takes out a bigger high-amperage wire with potentially a lot more current flow, like one of those ginormous inverter cables...

John Davies

Spokane WA

Edited January 24, 2021 by John E Davies

[mjrendon]

Here is the code for Texas. Still no wording specific to fuses.

[John E Davies]

5 minutes ago, mjrendon said:

Here is the code for Texas. Still no wording specific to fuses.

LOL, here is WA, same as Federal. https://app.leg.wa.gov/RCW/default.aspx?cite=46.37.340.

Will we have to check all of the other 48 states, just in case one says "no fuse please"? If there is one, it makes no sense for everybody to have to blindly follow along. 😉

John Davies

Spokane WA

Edited January 24, 2021 by John E Davies

[Overland]

I haven’t looked at mine to see if the wire is wrapped separately (if at all), but that seems like something that might give some peace of mind, fused or not. 

Edited January 24, 2021 by Overland

[mjrendon]

Likely to find differences in CA or LA. These states seem to differ from other states.

[JohnL]

If the fuse blows, wouldn't it happen only when current flows through it? This would only occur if the breakaway switch is activated resulting in nonfunctioning of the brakes as the OTT careens freely down the road disconnected from the TV.

This is the first trailer that I will own with one of these devices installed so those of you with experience please correct me if I misunderstand how these function.

[John E Davies]

A fuse will not blow when the breakaway switch is activated when everything is working correctly, because the normal current flow is less than the fuse rating.

The fuse is there to protect the wire if it should short out to ground, such as if a mouse chews through the insulation and the conductor touches the aluminum frame, and the wire suffers a severe current overload. The fuse pops, the wire is saved. If the same thing happens without a fuse, the wire overheats and literally melts somewhere. And your emergency brakes don’t work in either case. You still have to find and fix the problem, you just don’t have other burned stuff also, or, the worst case ever, have your beautiful Ollie burn to the pavement...

Most people do not understand, a fuse protects the wire, not the device at the end of it. Your stereo shorts out, the fuse blows, the wire is safe, you replace the stereo and replace the fuse... no worries. Electrical fires are not to be taken lightly, use Google to look at some pics of “automotive electrical fire images”. Like this one:

John Davies

Spokane WA

Edited January 25, 2021 by John E Davies

[JohnL]

Thank you John. That puts things in perspective. An inline fuse seems like a good safety addition regardless of regulatory issues.

The build for my Elite II (hull #769) is just beginning. Picking up in March.

[Overland]

43 minutes ago, JohnL said:

An inline fuse seems like a good safety addition regardless of regulatory issues.

Unless those regulatory issues have a reason for being. Shouldn’t the default assumption be that both Oliver and the brake manufacturer know what they’re doing?

[Frank C]

Definitely a good question... “To fuse or not to fuse?”   I think the manufacturer logic is that you wouldn’t want to have a fuse that could even have a possibility of blowing in an emergency breakaway situation.   If that switch is activated in a trailer breakaway scenario, I want the trailer brakes to be applied no matter what.  I don’t want a fuse to blow if it’s a slight over current situation, or a loose fuse holder or corroded fuse contacts that could affect the emergency braking function.  The fuse blowing would disable the emergency application of the brakes.  If having no fuse means that there might possibly be some damage to the wiring with a really prolonged high current draw after breakaway, then I think that’s a worthwhile trade off to make sure the brakes get applied and stop the trailer.  There’s no current flowing through that circuit in normal operation while towing or parked (although hungry mice could be a factor).  So I’m not worried about protecting anything other that the trailer itself in a breakaway emergency.  If there is some short circuit that is causing current flow in the breakaway circuit in a NON-emergency situation then it should be pretty self evident and I’ll probably notice that right away when I’m trying to move the trailer since the brakes will either be locked up all the time, or non-functional when I do the breakaway switch test as recommended.   

Edited January 25, 2021 by FrankC

[Landrover]

John 

It may be in your best interest not to try to preach putting a inline fuse between the brake away. If you chose to do it, that is your choice.  Some things are better left alone.

[Overland]

Personally, I think it’s an interesting question and I’d like to know the answer. But having said that, I do think that the default assumption should be that Oliver has done it correctly. Particularly since this is a safety issue.

For what it’s worth, the wiring diagram in my Dexter manual doesn’t show a fuse either, nor is it called for in the installation text.

While I agree that it seems logical to have a fuse, it also seems logical to have at least one bit of supporting documentation before we all start messing with our braking systems.

Searching around the internet, I can find discussions asking the same question for other trailers, but no answers other than opinion. So the only thing I can say for certain then is that the lack of a fuse isn’t something unique to our trailers. 

Edited January 25, 2021 by Overland

[mjrendon]

It is an interesting topic and deserves discussion and hopefully an answer that everyone is satisfied with.

The trouble with placing a fuse here is if there were to be an intermittent short that caused the fuse to blow, there would be no breakaway brakes and the user would not know this unless they checked the fuse or...

If something is needed here then something resettable might be more appropriate than a single use fuse.  

 

Edited January 25, 2021 by mjrendon