Cruisers Forum
 


Reply
  This discussion is proudly sponsored by:
Please support our sponsors and let them know you heard about their products on Cruisers Forums. Advertise Here
 
Thread Tools Search this Thread Rate Thread Display Modes
Old 13-01-2017, 12:41   #1
Registered User

Join Date: Dec 2016
Location: Narragansett Bay
Boat: 43' Ocean Sportfish
Posts: 32
Advice on fusing an Inverter

Hi All,

Did a search and didn't find what I was looking for. Hoping for little guidance on fusing an Inverter.

I am overhauling my battery distribution system currently. This has involved moving all of my ground and positive wires from the start and house banks up to heavy duty 600amp buss bars located 2-3ft from the batteries themselves. I would like to use an "on battery post" style fuse for the primary house bank and 2/0 wire from battery to the house on/off switch followed by 2/0 to the buss bar. Based on my reading, a 250amp fuse would be appropriate. I should point out that distribution panel and bank are in the engine room. So far I think I'm okay.

Phase two is the installation of an Inverter-Charger. Most likely candidate is a Victron 12v/2000W model. According to their instructions it should be wired with 2/0 cable within 5M of batteries. No problem there. Question relates to where to connect the inverter and how to fuse it. How should I attach the inverter to battery bank?

Can I wire directly to the buss bars (i'd like to since it keeps cables off the battery posts). If this is okay, then since it would be 2/0 cable all the way from the battery, via the switch and buss bar to the inverter, is the "on battery" fuse sufficient? The switch and buss bars all have higher amp capacity than the wire.

---or---

Should I wire as above but insert another fuse, perhaps a slow blow 250amp type T, just after my positive buss on way to inverter.

---or---

Should I wire the inverter directly to the batteries and install a separate fuse and if so, what should it be rated for. 12v at 4000w surge is 333amps. At 2000w its only 166amps.
Prospective is offline   Reply With Quote
Old 13-01-2017, 13:31   #2
Marine Service Provider

Join Date: Dec 2016
Location: Toronto On Canada
Boat: Bristol 45.5
Posts: 736
Re: Advice on fusing an Inverter

Hi Prospective

Remember , you are not fusing to protect the inverter, you are fusing to protect the wire .

What I did was put a 400 amp fuse right at the battery feeding every thing below that , I was using 4/0 wire . Every time you reduce wire size you should fuse it with the corresponding size of fuse for the max current of that wire in its application. .

The Victron has a fuse inside to protect it , you just need to think of protecting the wire that goes to it .

Regards John Tully
Typhoon is offline   Reply With Quote
Old 13-01-2017, 13:38   #3
Registered User

Join Date: Dec 2016
Location: Narragansett Bay
Boat: 43' Ocean Sportfish
Posts: 32
Re: Advice on fusing an Inverter

Quote:
Originally Posted by ColdEh Marine View Post
Hi Prospective

Remember , you are not fusing to protect the inverter, you are fusing to protect the wire .

What I did was put a 400 amp fuse right at the battery feeding every thing below that , I was using 4/0 wire . Every time you reduce wire size you should fuse it with the corresponding size of fuse for the max current of that wire in its application. .

The Victron has a fuse inside to protect it , you just need to think of protecting the wire that goes to it .

Regards John Tully
Thanks John, yes I was aware of that although my question probably made it seem otherwise. Based on your description and assuming I used 2/0 all the way from the battery, thru the switch and buss to the inverter I assume I would NOT need an additional fuse just for the inverter. I guess I was/am just not clear on if the inverter should have it's own independent fuse and if the terminal mounted MRBF fuses are okay or should it be a Class T as seems to be commonly recommended.
Prospective is offline   Reply With Quote
Old 13-01-2017, 13:59   #4
Marine Service Provider

Join Date: Dec 2016
Location: Toronto On Canada
Boat: Bristol 45.5
Posts: 736
Re: Advice on fusing an Inverter

Quote:
Originally Posted by Prospective View Post
Thanks John, yes I was aware of that although my question probably made it seem otherwise. Based on your description and assuming I used 2/0 all the way from the battery, thru the switch and buss to the inverter I assume I would NOT need an additional fuse just for the inverter. I guess I was/am just not clear on if the inverter should have it's own independent fuse and if the terminal mounted MRBF fuses are okay or should it be a Class T as seems to be commonly recommended.
Any fuse is better then none. I prefer class t fuses right out of the battery but if you have a MRBF right on the positive post that is rated for your wire you are just fine. From your positive buss bar that is fussed from the battery you can run directly to the inverter , no problem , as the wire will be protected. If you take the cover off the inverter you will see a large fuss inside . Your good to go .

This is my setup .

Regards John Tully

PS if you have not got your inverter yet , I can give you my review of the Victron .

Typhoon is offline   Reply With Quote
Old 13-01-2017, 14:00   #5
Registered User
 
daletournier's Avatar

Join Date: Jan 2012
Location: Australia
Boat: Catalina 470
Posts: 4,578
Re: Advice on fusing an Inverter

Im literally hooking up a 2000w 12v (240) inverter today. Im hooking straight to house batteries with 200a fuse.
Im not an expert, im copying the install of my 3000w 110v inverter that is already on the boat, its also how I did it on my last boat.

Sent from my vivo Y35 using Cruisers Sailing Forum mobile app
daletournier is offline   Reply With Quote
Old 13-01-2017, 14:22   #6
Registered User
 
rwidman's Avatar

Join Date: Feb 2008
Location: North Charleston, SC
Boat: Camano Troll
Posts: 5,176
Re: Advice on fusing an Inverter

I think it's better to connect the inverter cable to the load side of the battery switch. That's what you have a switch for, right?

As for the fuse, I would be really surprised if the installation instructions didn't cover that.
__________________
Ron
HIGH COTTON
rwidman is offline   Reply With Quote
Old 13-01-2017, 14:57   #7
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 995
Re: Advice on fusing an Inverter

One thing to keep in mind when you have two fuses of near identical rating effectively in series, if conditions are such that one blows the other may also blow. This can mean the loss of the entire yacht electrical service. Trying to steer with your toes while you replace a blown fuse in the dark holding a flashlight in your teeth can be a real experiment in manual dexterity.

Might want to consider a second fuse and switch right back to the main battery for the inverter. Mo stuff but maybe mo better.
Frankly is offline   Reply With Quote
Old 13-01-2017, 19:14   #8
Registered User

Join Date: Aug 2015
Posts: 474
Re: Advice on fusing an Inverter

300A Class T is usually good for a 2kw inverter.
boatbod is offline   Reply With Quote
Old 13-01-2017, 20:48   #9
Registered User

Join Date: Jun 2013
Location: canada
Posts: 4,634
Re: Advice on fusing an Inverter

Run 4/0 from battery to bus bar unfused if it's only a couple feet. Or at 400a if you really want. From the bus bar run fused 2/0 to your house switch. (Anl or mrbf). And run 2/0 from bus to the inverter switch and class t fuse. Likly 300a for a 2000w.

Each needs own switch and fusing.

Leave the bus bar as unswitched. Good place for your alt to connect to as well.
smac999 is online now   Reply With Quote
Old 13-01-2017, 20:51   #10
Registered User

Join Date: Jun 2013
Location: canada
Posts: 4,634
Re: Advice on fusing an Inverter

Quote:
Originally Posted by rwidman View Post
I think it's better to connect the inverter cable to the load side of the battery switch. That's what you have a switch for, right?

As for the fuse, I would be really surprised if the installation instructions didn't cover that.

You never connect an inverter charger to the load side of a house switch.

A: If you turn it off your batteries don't charge
B: if you turn it off, all house loads are still fed direct from charger output. Which is really bad for it. Plus your house is live with the house switch off.

The inverter charger gets its own switch from the battery
smac999 is online now   Reply With Quote
Old 14-01-2017, 07:45   #11
Registered User

Join Date: Dec 2016
Location: Narragansett Bay
Boat: 43' Ocean Sportfish
Posts: 32
Re: Advice on fusing an Inverter

Excellent point. I had not considered B. Caulders book has an example with inverter wired to supply side of the switch which I guess would be an option to keep it off the battery terminal.
Prospective is offline   Reply With Quote
Old 14-01-2017, 09:39   #12
Registered User
 
S/V Alchemy's Avatar

Join Date: May 2008
Location: Nova Scotia until Spring 2021
Boat: Custom 41' Steel Pilothouse Cutter
Posts: 4,976
Re: Advice on fusing an Inverter

Quote:
Originally Posted by ColdEh Marine View Post
Hi Prospective

Remember , you are not fusing to protect the inverter, you are fusing to protect the wire .

What I did was put a 400 amp fuse right at the battery feeding every thing below that , I was using 4/0 wire . Every time you reduce wire size you should fuse it with the corresponding size of fuse for the max current of that wire in its application. .

The Victron has a fuse inside to protect it , you just need to think of protecting the wire that goes to it .

Regards John Tully
This is correct as I understand it and was what the Xantrex manual suggested for my similar inverter. I have a 300 amp T-type fuse and 4/0 ga. to the inverter.


I have 2/0 ga. wire (same lengths) as both interconnections between batteries and to the main busses. I also have both positive and negative shut-offs...it's a steel boat and this is recommended, although I got the idea from French production boats. This may help: The world encompassed: Wired and perspired
__________________
Can't sail? Read about our travels at https://alchemyonpassage.blogspot.com/. Can't sleep? Read www.alchemy2009.blogspot.com for fast relief. Can't read? Avoid www.volumesofsalt.blogspot.com, because it's just personal reviews of sea books.
S/V Alchemy is offline   Reply With Quote
Old 14-01-2017, 13:28   #13
Registered User

Join Date: Jan 2011
Location: Lake Macquarie
Boat: Farr 1020
Posts: 482
Re: Advice on fusing an Inverter

Quote:
Originally Posted by Frankly View Post
One thing to keep in mind when you have two fuses of near identical rating effectively in series, if conditions are such that one blows the other may also blow. This can mean the loss of the entire yacht electrical service. Trying to steer with your toes while you replace a blown fuse in the dark holding a flashlight in your teeth can be a real experiment in manual dexterity.

Might want to consider a second fuse and switch right back to the main battery for the inverter. Mo stuff but maybe mo better.
Technically, this is called "discrimination". We always reduce the size as we go down the line so the one that blows is closest to the problem that caused the high current.
Issues arise when folk mix fuses and circuit breakers. Quick and Slow break safety devices can also mix things up. Yes, we can calculate it all and look at exactly what happens when, but I have seen several so-called professional engineers get it seriously wrong many times as well. We also use Fault Levels and need the circuit impedance to establish what the current can be for a short time to ensure bus bars and cable sizes are correct.
Keep it simple, fuse the supply to each line directly at the take-off and use the same type of fuse throughout, then step down in size to the one needed to protect the wire.
Djarraluda is offline   Reply With Quote
Old 15-01-2017, 06:40   #14
Registered User

Join Date: Jan 2014
Location: Panama City FL
Boat: Island Packet 32 Keel/CB
Posts: 995
Re: Advice on fusing an Inverter

"Technically, this is called "discrimination".


North of the Equator we refer to that as system coordination or system selectivity. Under an overload situation if you have a 100 Amp main fuse and a 15 Amp downstream fuse and something in the VHF fails causing the current draw to hit 30 amps then the 15 amp fuse will clear the problem and the 100 Amp will keep on supplying the remainder of the electrical loads.

However if the VHF develops a short circuit and the current is now 500 Amps then it is often next to impossible to keep both fuses from blowing and the entire electrical system goes down. On big AC power systems there are usually a wide variety of breakers/ fuses with various trip curves that can mediate this situation. On DC equipment our choices are not so broad, so sometimes we just have do the best we can to protect the system but spend a little time in the dark. A good case for breakers where possible and one of many reasons to not fuse any big common negative returns.
Frankly is offline   Reply With Quote
Old 16-01-2017, 05:28   #15
cruiser

Join Date: Jan 2012
Location: Lake Ontario
Boat: Ontario 38 / Douglas 32 Mk II
Posts: 3,250
Re: Advice on fusing an Inverter

Quote:
Originally Posted by Prospective View Post
Hi All,

Did a search and didn't find what I was looking for. Hoping for little guidance on fusing an Inverter.

I am overhauling my battery distribution system currently. This has involved moving all of my ground and positive wires from the start and house banks up to heavy duty 600amp buss bars located 2-3ft from the batteries themselves. I would like to use an "on battery post" style fuse for the primary house bank and 2/0 wire from battery to the house on/off switch followed by 2/0 to the buss bar. Based on my reading, a 250amp fuse would be appropriate. I should point out that distribution panel and bank are in the engine room. So far I think I'm okay.

Phase two is the installation of an Inverter-Charger. Most likely candidate is a Victron 12v/2000W model. According to their instructions it should be wired with 2/0 cable within 5M of batteries. No problem there. Question relates to where to connect the inverter and how to fuse it. How should I attach the inverter to battery bank?

Can I wire directly to the buss bars (i'd like to since it keeps cables off the battery posts). If this is okay, then since it would be 2/0 cable all the way from the battery, via the switch and buss bar to the inverter, is the "on battery" fuse sufficient? The switch and buss bars all have higher amp capacity than the wire.

---or---

Should I wire as above but insert another fuse, perhaps a slow blow 250amp type T, just after my positive buss on way to inverter.

---or---

Should I wire the inverter directly to the batteries and install a separate fuse and if so, what should it be rated for. 12v at 4000w surge is 333amps. At 2000w its only 166amps.
The correct answer is follow ABYC standards to the letter. If you don't know the standards intimately, hire someone who does. A lot of the advice you are receiving in this thread is total BS and unsafe.

I know this because not one person has asked the max current rating of your distribution panel(s), and other connected loads like windlass or
bow thruster.

Only after all loads are calculated, can you calculate cable requirements, and the fuse requirements.
Half those responding may fail a marine survey miserably. How will you know which half you should listen too?
ramblinrod is offline   Reply With Quote
Reply

Tags
inverter

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
fusing a 450 Ah bank mariner36bob Electrical: Batteries, Generators & Solar 32 30-03-2014 12:29
Battery Connections and Fusing nitpik Electrical: Batteries, Generators & Solar 6 17-02-2012 04:20
Proper fusing of various charging sources R_C Electrical: Batteries, Generators & Solar 41 25-12-2011 20:30
Fusing Solar? Boracay Electrical: Batteries, Generators & Solar 3 11-12-2009 03:36
Fusing the Battery Cable sailingharry Electrical: Batteries, Generators & Solar 44 07-10-2009 17:42

Advertise Here


All times are GMT -7. The time now is 22:58.


Google+
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.
Social Knowledge Networks
Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.

ShowCase vBulletin Plugins by Drive Thru Online, Inc.