RV.Net Open Roads Forum: Tech Issues: Is a fuse a fuse?

RV Blog

  |  

RV Sales

  |  

Campgrounds

  |  

RV Parks

  |  

RV Club

  |  

RV Buyers Guide

  |  

Roadside Assistance

  |  

Extended Service Plan

  |  

RV Travel Assistance

  |  

RV Credit Card

  |  

RV Loans

Open Roads Forum Already a member? Login here.   If not, Register Today!  |  Help

Newest  |  Active  |  Popular  |  RVing FAQ Forum Rules  |  Forum Posting Help and Support  |  Contact  

Search:   Advanced Search

Search only in Tech Issues

Open Roads Forum  >  Tech Issues

 > Is a fuse a fuse?

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 3  
Next
Sponsored By:
Vintage465

Prunedale CA.

Senior Member

Joined: 05/02/2015

View Profile


Offline
Posted: 11/09/19 09:29pm Link  |  Quote  |  Print  |  Notify Moderator

I'm fusing my solar panels individually in the combiner box before they are combined. Initially, I purchased the 15a MC-4 fuse holder and the connectors. This came out to about 6-1/2" long. Too long for my combiner box with all the other hardware in there. So, can I use any automotive inline type fuse and fuse holder so long as the the fuse size is right and the wire size(10ga) is the same? The reason I ask is the conductor/fuse is real small on an automotive 15a and I always concern my self with not carrying as much juice cause of the small fuse link compared to the 10ga wire? Meaning, is there a "special" solar fuse that carries more juice?

Thanks,


V-465
2013 GMC 2500HD Denali. 2015 Creekside 20fq w/450 watts solar. Retiring in 2021, then look-out road, here we come!

ktmrfs

Portland, Oregon

Senior Member

Joined: 06/22/2005

View Profile


Offline
Posted: 11/09/19 09:45pm Link  |  Quote  |  Print  |  Notify Moderator

fuses are rated for interupt current, interupt time, and arc interuption voltage. that is how much current before it trips, how long an overcurrent takes before it blows, and how high the voltage can be and still interupt the current and not sustain an arc thus not interupting the current flow.

AFAIK for solar panels, since most are used in houses and many are interconnected to the house power feed and power line there are spec's for the fuses to be used.

Now, when used with a trailer, likely another story. no line connection, no feed to the power grid.

Now I am by no means an expert on this application, but if it was me using a 15A auto blade type fuse and fuseholder I would feel comfortable.

BTW 14Ga wire is rated for 15A, 10Ga wire is rated for 30A in romex, higher in individual strands. The 10Ga gives lower voltage drop.


2011 Keystone Outback 295RE
2004 14' bikehauler with full living quarters
2015.5 Denali 4x4 CC/SB Duramax/Allison
2004.5 Silverado 4x4 CC/SB Duramax/Allison passed on to our Son!


time2roll

Southern California

Senior Member

Joined: 03/21/2005

View Profile



Good Sam RV Club Member


Posted: 11/09/19 10:05pm Link  |  Quote  |  Print  |  Notify Moderator

You have more than two panels in parallel? What are the panel ratings? link?

If you are using MC4 why even have a combiner box? MC4 combiner is fine and you can get #8 MC4 down to the controller if you need it.

Otherwise yes any 12v fuse is fine.


2001 F150 SuperCrew
2006 Keystone Springdale 249FWBHLS
675w Solar pictures back up

wa8yxm

Wherever I happen to park

Senior Member

Joined: 07/04/2006

View Profile


Offline
Posted: 11/10/19 04:17am Link  |  Quote  |  Print  |  Notify Moderator

Fuse needs to be rated to handle the full voltage of the panel in full sunlight. And for safety I like to double that. So a 24 volt panel would need 48 volt rated fuses (Or at least 36) and DC rated.

The only other thing would be the "inline resistance) of the fuse (The resistance pin to pin not blown) likely too low for your meter to measure but I'm not sure how the "Solar rated" fuses compare to standard automotive/house fuses in this aspect.

And as someone else mentioned... The fuse's "Speed" Fast. slow. standard. ultra fast) That is how quickly it blows if overloaded.


Home is where I park it.
Kenwood TS-2000 housed in a 2005 Damon Intruder 377


Vintage465

Prunedale CA.

Senior Member

Joined: 05/02/2015

View Profile


Offline
Posted: 11/10/19 07:39am Link  |  Quote  |  Print  |  Notify Moderator

time2roll wrote:

You have more than two panels in parallel? What are the panel ratings? link?

If you are using MC4 why even have a combiner box? MC4 combiner is fine and you can get #8 MC4 down to the controller if you need it.

Otherwise yes any 12v fuse is fine.


I have a couple reasons for a combiner box. First, it came with a Zamp combiner box that was rather butchered up when the dealer installed the existing Solar. There was MC-4 cable wrapped round and round in circles on the roof and in the attic. When I yank the the butchered Zamp box, something needs to go back in it's place and since I'm adding a third panel, that something might as well be a combiner box to tidy up the roof wiring. And I'm not really using any MC-4 Connections. Was going to use an MC-4 Fuse holder but they don't fit in the combiner box and I'm trying to keep all connections in the box.

Ed_Gee

Central Oregon coast - Winter in AZ

Senior Member

Joined: 01/14/2015

View Profile


Offline
Posted: 11/10/19 08:01am Link  |  Quote  |  Print  |  Notify Moderator

Not sure I understand why one would fuse a solar panel. What rating fuse would you use? ...the solar panel is simply incapable of sourcing higher current than its maximum output.....a fuse could never blow. The other end is not a current source assuming it is a charge controller, so nothing that could provide current to blow a fuse there, either..... am I missing something?


Ed - on the Central Oregon coast
2018 Winnebago Fuse 23A
Scion xA toad

alaska dennis

homer ak

Full Member

Joined: 04/12/2010

View Profile


Offline
Posted: 11/10/19 09:31am Link  |  Quote  |  Print  |  Notify Moderator

In parallel panel installation you need isolation more than fusing. Install isolation diodes in place of the fuses.

theoldwizard1

SE MI

Senior Member

Joined: 09/07/2010

View Profile


Offline
Posted: 11/10/19 09:38am Link  |  Quote  |  Print  |  Notify Moderator

IIRC, automotive fuses rating are based on a maximum of 32VDC-36VDC. Voltages above that may cause the fuse to blow (48VDC) the fuse to blow "early".

ktrmrfs is spot on with his statements. What people need to understand that the "variability" of a fuse. A 15A fuse will "carry" 16A of current for hours and not blow. It might even carry 20A for several seconds.

Back to the OP original concern. ATO/ATC sized inline fuses older with either 10AWG or 12AWG are readily available online. Although you can get these fuses up to 40A, If I needed a fuse larger than 30A I think i would use a Maxi-fuse. These typically come with 8AWG wire.

ktmrfs

Portland, Oregon

Senior Member

Joined: 06/22/2005

View Profile


Offline
Posted: 11/10/19 09:52am Link  |  Quote  |  Print  |  Notify Moderator

theoldwizard1 wrote:

IIRC, automotive fuses rating are based on a maximum of 32VDC-36VDC. Voltages above that may cause the fuse to blow (48VDC) the fuse to blow "early".

ktrmrfs is spot on with his statements. What people need to understand that the "variability" of a fuse. A 15A fuse will "carry" 16A of current for hours and not blow. It might even carry 20A for several seconds.

Back to the OP original concern. ATO/ATC sized inline fuses older with either 10AWG or 12AWG are readily available online. Although you can get these fuses up to 40A, If I needed a fuse larger than 30A I think i would use a Maxi-fuse. These typically come with 8AWG wire.


voltage above the fuse rated voltage will NOT cause it to blow provided current is at or below the fuse rated current . But voltages above the rated voltage may cause the fuse to continue to arc when it does blow. Just like massive current can cause the arc to continue even below the rated voltage. That's why fuses have max voltage rating and max current interupt ratings.

ktmrfs

Portland, Oregon

Senior Member

Joined: 06/22/2005

View Profile


Offline
Posted: 11/10/19 09:59am Link  |  Quote  |  Print  |  Notify Moderator

Ed_Gee wrote:

Not sure I understand why one would fuse a solar panel. What rating fuse would you use? ...the solar panel is simply incapable of sourcing higher current than its maximum output.....a fuse could never blow. The other end is not a current source assuming it is a charge controller, so nothing that could provide current to blow a fuse there, either..... am I missing something?


single panel I agree. Multiple panels another story. Let's assume you have 6 panels in parallel. One panel develops an internal short positive to negative, each panel can supply 15A, Now all the sudden you have 5 panels suppling up to a total of 60A through the wiring on the shorted panel. not a good idea. The fuse serves as a isolation device.

Fusing requirements for solar panels are more focused on house grid tie applications where you could have a dozen or more panels in parallel.

Reply to Topic  |  Subscribe  |  Print Topic  |  Post New Topic  | 
Page of 3  
Next

Open Roads Forum  >  Tech Issues

 > Is a fuse a fuse?
Search:   Advanced Search

Search only in Tech Issues


New posts No new posts
Closed, new posts Closed, no new posts
Moved, new posts Moved, no new posts

Adjust text size:

© 2019 CWI, Inc. © 2019 Good Sam Enterprises, LLC. All Rights Reserved. | Terms of Use | PRIVACY POLICY | YOUR PRIVACY RIGHTS