Looking for a 300 amp curcuit breaker???

[Nick Badame Refrig/ACC]

Hi Guy's,

Does anyone make a 300 amp DC [0000ga] curcuit breaker?

My inline 300 amp class T fuse blows out at times and they are not cheap... I run one of my heat pumps on my inverter

curcuit and the other on deticated shore power. My inverter and battery bank are very capable of handeling the heat pump

but, there are times when we have a power outage while plugged into my home. When this happens, [like twice yesterday]

the outage was 5 to 10 seconds. Just long enough for the compressor in my heat pump to cycle off and then try to restart.

This causes the compressor to lock rotor and over draw on amprage. Then the 300 amp class t fuse blows...

Two $40 fuses in one day are enough to make you maaaad.... Nobody locally carries them and I'm always forced to order them

online so a thought of a curcuit breaker would be nice!

Thanks
Nick-

[Joe Camper]

I have only blown mine once but I would like to do this too. Don't remember what I paid but it was a bunch and needed to be ordered.

[Len Silva]

They are available, they are used in the telephone industry power plants, but they are going to be both expensive and hard to find.  Look under telephone surplus.

[Sean]

Dozens of 'em on eBay for less than twenty bucks:
http://shop.ebay.com/i.html?_nkw=circuit+breaker+300+amp

-Sean
http://OurOdyssey.BlogSpot.com

[Len Silva]

Sean,

Knowing your penchant for quality and safety, I'm somewhat surprised that you would suggest those circuit breakers.  I know nothing about them and my opinion is based solely on the price.  When a circuit breaker is half the price of a fuse, and I know that quality DC breakers in that range cost hundreds, I would not put one of those in my bus.

I would be afraid that it would fail to operate or that it would overheat and cause a fire.

[belfert]

I have a 225 amp DC breaker in my bus.  That thing is huge.  It is about 9 inches long, 4 inches wide, and 4 inches deep.  No idea on the cost as my friend had it in his garage and gave it to me.  It actually came from a large UPS.  My friend scrapped out all the copper in the UPS.

I suspect it may be a three phase breaker repurposed to do DC based on the design of the breaker.

[Sean]

Len,

You raise a good point.  Generally, though, as long as they are tested and inspected before installation I am not overly uncomfortable with these sorts of products.  However I did just notice another issue -- I failed to notice Nick's wire specification for 4/0 in the OP.  I'm pretty sure the less expensive ones on eBay accept a maximum of 0 or 00.

Which prompts me to ask, Nick:  With 4/0 cable rated for quite a bit more than 300a, what's the limiting factor causing you to use a 300a fuse?  Is this specified by your inverter manufacturer?  I've also got 4/0 main cables, and I am using 450a catastrophe fuses.

I think you will have a hard time finding any breaker rated at 300a that has lugs large enough for 4/0.

One thing you might consider is changing from Class-T style fuses to ANL style, which are readily available in 300a ratings.  ANL fuses are less than $15 in quantity one, and I expect you could get a package of three or four for $10 apiece.  Here again the lug posts will be smaller than the Class-T posts, but at least you can get the larger lugs onto the posts.

-Sean
http://OurOdyssey.BlogSpot.com

[Len Silva]

Nick,

Aside from the issue of blowing fuses, I am very surprised that you do not have a time delay on the compressor start.  I thought that 45 seconds or so was pretty much standard on RV units.  Shouldn't be much of a hill for a refer man.

[jjrbus]

I'm glad Sean responded! When doing my electrical system I saw the price of the recommended class t fuse and holder and almost had a coronary. It's a bus, not the space shuttle.
So I checked around a bit and went with the ANL 300 amp. Had no problems in 10 year's.

                                HTH  JIm

[Nick Badame Refrig/ACC]

Hi Guy's,

Len, I do have a delay in the dometic comfort control center but, it run on 12v dc and when

land power gets interupted, the 12 delay is not in play. I will have to work on that!!

Sean, Len, thanks for all your information. I think I should switch to ANL. I just found an ANL fuse block

that will except 4/0 for $50 and the fuses are $12/15 bucks. I know most marine stores stock then too..

I sure would rather have a curcuit breaker.....

Nick-

[Len Silva]

Nick,

Seems like a simple fix would be to run the 12 volt control voltage through a 120 volt relay.  If the AC drops out, it would open the 12 VDC and start the timer cycle.  One relay could control the 12 volts to all your air conditioners.

[dbenck]

Nick I may have one or two at the shop. I used them on my feed for two Trace inverters. I am out of town untill tomorrow, but will check when I get back and let you know. Either 250 or 300 amp DC.

David P. Benck

[Nick Badame Refrig/ACC]

Hi Len,

I have a simple solution to the delay problem. I will install a [delay on break] solid state timer on each of my HP's.

David,

Yes... let me know what you have in your shop!!

Thanks
Nick-

[RickB]

Nick,

They were terribly expensive at Telephone and electrical supply places and then I found the motherlode. Marine shops, I found a huge selection and really great prices. I can't remember exactly how much but it was like a tenth of what it cost me at an electrical supply shop. I bought 3 of them if I didn't have my bus in storage 80 miles away I'd send you one for Christmas. If Dave B doesn't have one I'll go to West Marine in Stillwater and get you some.

RB

[twocnusa]

nick, look up hi-amp circuit breakers at  www.waytekwire.com  good luck, ron