GlennWest Posted December 5, 2019 Report Share Posted December 5, 2019 My Magnums MS4448PAE call for 2/0 wire with 175 amp protection. I intend to use a fuse and a cut off switch. This will be X2. Is it necessary to have a breaker also? Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Daveh Posted December 5, 2019 Report Share Posted December 5, 2019 Unless they have changed their manual--one fuse Quote Dave and Lana Hasper Link to comment Share on other sites More sharing options...
oldjohnt Posted December 6, 2019 Report Share Posted December 6, 2019 (edited) Glenn, in order to provide "Overcurrent Protection" you need only one device and I often prefer fuses versus breakers. An On/Off switch is a separate issue and hey I have no problem with those. Sure, a proper circuit breaker could ??? serve as BOTH if that's YOUR choice and Magnum approves of such ??????????? NO you DO NOT need a Fuse plus a Breaker to provide "Overcurrent Protection" ...………….The time current curves would determine which opens first. NOTE "Overcurrent Protection" for huge cables FROM a battery TO an Inverter need located at the energy source IE the battery, not far downstream leaving cable unprotected !!!!!!!!!!! John T Edited December 6, 2019 by oldjohnt Quote Link to comment Share on other sites More sharing options...
GlennWest Posted December 6, 2019 Author Report Share Posted December 6, 2019 The Magnum Panels all come with breakers. That is why I was asking. I agree with yall. one device is enough. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Zulu Posted December 6, 2019 Report Share Posted December 6, 2019 (edited) 1 hour ago, GlennWest said: My Magnums MS4448PAE call for 2/0 wire with 175 amp protection. I intend to use a fuse and a cut off switch. This will be X2. Is it necessary to have a breaker also? I suggest a 175A breaker instead of a fuse. I used to use fuses too until I had an electrical issue that blew the fuse. Then what? Keep replacing the fuse until you locate the problem? Good luck with that. Also, you get a fuse & cut off switch in one. Edited December 6, 2019 by Zulu Quote SKP #79313 / Full-Timing / 2001 National RV Sea View / 2008 Jeep Wrangler Rubiconwww.rvSeniorMoments.comDISH TV for RVs Link to comment Share on other sites More sharing options...
oldjohnt Posted December 6, 2019 Report Share Posted December 6, 2019 1 hour ago, GlennWest said: The Magnum Panels all come with breakers. That is why I was asking. I agree with yall. one device is enough Glenn built in breakers are all well and good for their intended purpose and I'm sure your Magnum is properly designed... HOWEVER FYI even if you are already aware for those who aren't, don't forget in order to provide "Overcurrent Protection" for the huge cables FROM the battery TO the Inverter those overcurrent protection devices (fuses or breakers) must be located at the source of energy the BATTERY not later somewhere downstream which would leave that portion of the cable (from battery to a breaker inside the Inverter) UNPROTECTED !!!!!!!!!!!!!!!! Yikes !!!!!!!!!!! That's a serious potential hazard with 2/0 Cables and a 21 KWH battery !!!! A breaker can only detect current that flows THROUGH IT not elsewhere like from a POS cable shorted to the RV frame BEFORE the Inveter !!!!! Of course there's no problem in overcurrent protection at BOTH locations (battery and Inverter) as well as On/Off switches NOTE in the area of Electrical Power Distribution there are applications where fuses are favored and others where circuit breakers may be NOTE for certain applications "Switch Rated" breakers are required that may not be necessary elsewhere John T Longgggggggg retired n rusty power distribution engineer and codes change so NO warranty...Consult the manufacturer and local practicing electrical engineers and electricians where fire and life safety is concerned ………... Quote Link to comment Share on other sites More sharing options...
jcussen Posted December 6, 2019 Report Share Posted December 6, 2019 I am also using a 175 amp breaker on the positive lead between my battery and inverter, and normal 20 and 50 amp breakers on the ac outputs. Quote Foretravel 40ft tag 500hp Cummins ISM 1455 watts on the roof, 600 a/h's lithium in the basement. Link to comment Share on other sites More sharing options...
GlennWest Posted December 6, 2019 Author Report Share Posted December 6, 2019 (edited) I have #4 running from each battery to a 8 post buss bar. Leaving buss bar with 2/0 to protection then inverters. Edited December 6, 2019 by GlennWest Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
GlennWest Posted December 6, 2019 Author Report Share Posted December 6, 2019 The suggestion of just the breaker is tempting. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
GlennWest Posted December 6, 2019 Author Report Share Posted December 6, 2019 6 hours ago, jcussen said: I am also using a 175 amp breaker on the positive lead between my battery and inverter, and normal 20 and 50 amp breakers on the ac outputs. I had not intended to add breakers on the out side of inverters. It will connect to panel box in RV. It has its own 50amp breaker Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Sehc Posted December 6, 2019 Report Share Posted December 6, 2019 I do not trust breakers on high ampere dc circuits. I do use Blue Sea battery disconnect switches. I also use these MRBF on the bus bar. https://shop.marinehowto.com/products/blue-sea-marine-rated-battery-fuse They save a couple of connections each. A catastrophic fuse could be required at the battery before the bus bar if the cable length is too long. Quote Link to comment Share on other sites More sharing options...
oldjohnt Posted December 6, 2019 Report Share Posted December 6, 2019 6 hours ago, GlennWest said: I had not intended to add breakers on the out side of inverters. It will connect to panel box in RV. It has its own 50amp breaker Glenn, I would expect the AC Output of the Inverter has its own built in limiting protection so no additional DIY after market protection would then be required. Of course, as I explained below, your RV Distribution Panel indeed has "its own 50 Amp Main Breaker" to monitor the current that passes THROUGH and AFTER it, but that doesn't protect the WIRING FROM Inverter output TO the Panels 50 Amp Main, the Magnums output protection and limiting should take care of that. 1 hour ago, Sehc said: I do not trust breakers on high ampere dc circuits. I do use Blue Sea battery disconnect switches. I also use these MRBF on the bus bar. https://shop.marinehowto.com/products/blue-sea-marine-rated-battery-fuse They save a couple of connections each. A catastrophic fuse could be required at the battery before the bus bar if the cable length is too long. SEHC DITTO Indeed there are as I recall numerous applications where fuses are preferred over circuit breakers. DITTO Also catastrophic fuse protection can be required "at or near" the battery, I forget the distances and current and voltage etc. requirements. Yall be safe and take care now John T Quote Link to comment Share on other sites More sharing options...
GlennWest Posted December 6, 2019 Author Report Share Posted December 6, 2019 1 hour ago, Sehc said: I do not trust breakers on high ampere dc circuits. I do use Blue Sea battery disconnect switches. I also use these MRBF on the bus bar. https://shop.marinehowto.com/products/blue-sea-marine-rated-battery-fuse They save a couple of connections each. A catastrophic fuse could be required at the battery before the bus bar if the cable length is too long. My positive cables are 18" from batteries to bussbar. Negatives are 24". Negatives at bottom so they had to be longer. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Zulu Posted December 6, 2019 Report Share Posted December 6, 2019 3 hours ago, Sehc said: I do not trust breakers on high ampere dc circuits. Midnite Solar’s F-series magnetic/hydraulic breakers seem to have some pretty impressive specs. Glenn, ask on the MidNite Solar forum. Quote SKP #79313 / Full-Timing / 2001 National RV Sea View / 2008 Jeep Wrangler Rubiconwww.rvSeniorMoments.comDISH TV for RVs Link to comment Share on other sites More sharing options...
jcussen Posted December 6, 2019 Report Share Posted December 6, 2019 8 hours ago, GlennWest said: I had not intended to add breakers on the out side of inverters. It will connect to panel box in RV. It has its own 50amp breaker Mine is in the S&B, so the 50 and 20 breakers are in a breaker box with receptacles, nothing else between inverter and breaker box. Quote Foretravel 40ft tag 500hp Cummins ISM 1455 watts on the roof, 600 a/h's lithium in the basement. Link to comment Share on other sites More sharing options...
oldjohnt Posted December 6, 2019 Report Share Posted December 6, 2019 4 hours ago, GlennWest said: My positive cables are 18" from batteries to bussbar. Negatives are 24". Negatives at bottom so they had to be longer. George, that may well qualify for having "Overcurrent Protection" "At or Near" the energy source. Its been too long and I would have to look up the specs concerning amperage and wire size and voltage etc. Again, the Magnum likely has its own built in limiting and overcurrent protection ON ITS OUTPUT and if so you're good FROM it TO the AC Distribution Panel John T Quote Link to comment Share on other sites More sharing options...
GlennWest Posted December 7, 2019 Author Report Share Posted December 7, 2019 Based on above suggestions I believe I'll go with fuse directly leaving bussbar. They will be virtually no way for my cables to short out. Short runs and plywood, not steel around it. I will also enclose this area so nothing going in there. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
oldjohnt Posted December 7, 2019 Report Share Posted December 7, 2019 3 hours ago, GlennWest said: Based on above suggestions I believe I'll go with fuse directly leaving bussbar. Good plan Glenn, works for me and likely ???? complies with any applicable codes. John T Quote Link to comment Share on other sites More sharing options...
Sehc Posted December 7, 2019 Report Share Posted December 7, 2019 Good plan. I only know the marine rule, no more than 7 inches from battery positive. But with no metal, where could it short? Quote Link to comment Share on other sites More sharing options...
noteven Posted December 7, 2019 Report Share Posted December 7, 2019 I like marine breakers they make a handy disconnect when the fire starts because those DC batteries are bizzy trying to discharge themselves to earth. Quote "Are we there yet?" asked no motorcycle rider, ever. Link to comment Share on other sites More sharing options...
GlennWest Posted December 7, 2019 Author Report Share Posted December 7, 2019 If those lithium batteries goes up in flames, you won't get to the disconnect. But the BMS suppose to control this. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
GlennWest Posted December 8, 2019 Author Report Share Posted December 8, 2019 (edited) On 12/6/2019 at 8:35 AM, Sehc said: I do not trust breakers on high ampere dc circuits. I do use Blue Sea battery disconnect switches. I also use these MRBF on the bus bar. https://shop.marinehowto.com/products/blue-sea-marine-rated-battery-fuse They save a couple of connections each. A catastrophic fuse could be required at the battery before the bus bar if the cable length is too long. I do believe I will get those MRBF fuses. Like less cables and space savings. also any reason why not on battery post? These little fuses would fit well there.The 3/8" ring would be a little large. Battery is just under 1/4" but metric, M6. Surface area is good though. Washer on top should cause good contact. Would need 3 instead of 2 but all my cables will be protection. Edited December 8, 2019 by GlennWest Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
Sehc Posted December 8, 2019 Report Share Posted December 8, 2019 (edited) I used these on my battery terminals. I have had no problem after 3 years. I use a voltmeter to check for voltage drop when servicing my battery. The main problem is clearance above. These are higher than the posts. The ring fits a 5/16 stud. Edited December 8, 2019 by Sehc add correct size number Quote Link to comment Share on other sites More sharing options...
GlennWest Posted December 8, 2019 Author Report Share Posted December 8, 2019 I have feet above for clearance. Just what I wanted to hear. I could put a stud in my battery. Quote 2003 Teton Grand Freedom towed with 2006 Freightliner Century 120 across the beautiful USA welding pipe.https://photos.app.goo.gl/O32ZjgzSzgK7LAyt1 Link to comment Share on other sites More sharing options...
oldjohnt Posted December 8, 2019 Report Share Posted December 8, 2019 Glenn, wow talk about any code requirements (NEC or Marine or RV) to provide Overcurrent Protection for the feeders "AT OR NEAR THE SOURCE" I think that pretty well has you covered...…...Id use those in a heartbeat provided they are the sufficiently rated for your current requirements ???? Also anytime you can reduce the number of cables and extra connections that's good. Now that you have "Overcurrent Protection" well covered for the feeders FROM the battery TO Load Inputs, you can install a Disconnect at loads such as Inverters or others for safety and convenience and/or as required (Unit may already have that covered??) If you want a pure disconnect only or say a breaker suitable for switching that's between you and what the manufacturers suggest (don't want to void any warranty) and if its needed ??? but I prefer and have at least a disconnect method especially for loads far removed from my batteries. As you already know having the Inverter close to the battery saves on line voltage drop and wasted heat energy concerns...…. Although Marine Grade is great and typically high quality and corrosion resistant and has excellent vibration resistance, using it in strictly RV applications may or may not be absolutely required BUT ITS SO GOOD AND SUCH HIGH QUALITY I've used it and prefer it. I often (right now as a matter of fact) am dry camped right on a beach so Marine grade is a good thing required or not. I still want to camp right next to you and plug into your energy source as you have enough to power an entire zip code lol John T Quote Link to comment Share on other sites More sharing options...
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