Fuses or Breakers

[Fred Mc]

I am planning to install a Xantrax 1750 Inverter and the manual calls for a 250A Class T fuse. These fuses are quite expensive. Can I use a 250A breaker which is a LOT cheaper.

Thanks

Fred

[luvrbus]

Your breaking DC voltage I don't know if a AC breaker would work or not but we will find out 

[Geoff]

Here is a cheaper alternative, an ANL fuse available on eBay:

https://m.ebay.com/itm/High-Quality-1-0-4-8-Gauge-ANL-Fuse-Holder-2-Pack-Gold-300-Amp-300A-Fuse-USA/232352201432?hash=item3619453ad8%3Ag%3APicAAOSwi7RZKyNB%3Asc%3AUSPSFirstClass%2186305%21US%21-1&_nkw=samurai+sanl1020&_from=R40&rt=nc

[luvrbus]

There was talk about where you installed the fuse too some say on the positive + side,Sean told me to install mine on the negative - which I done ,I still don't understand what difference it made 

[richard5933]

You want to use a fuse. They break faster, and if this fuse blows you've got bigger problems than having to replace the fuse. If you size the inverter for the intended load, the fuse should only blow on a catastrophic failure, like a short circuit.

[Geoff]

There was talk about where you installed the fuse too some say on the positive + side,Sean told me to install mine on the negative - which I done ,I still don't understand what difference it made

On my Trace, I installed it on the positive DC lead as per directions.  But the last bus I worked on had it on the positive and negative sides.  The negative side was blown.  That is how I have the one in the picture-- I got the fuses and holder for the price of one fuse.

[luvrbus]

That is a another thing I don't understand is why they want a class T,the only difference I see between the T and the ANL the ANL has a element (link) that burns into and the class T has sand or glass I don't know which it melts breaking the circuit. 

[Iceni John]

Class T fuses are very quick-blowing, so maybe that's why Xantrex wants them used.   Magnum doesn't specify what type of fuse for their inverters, so I use a 250A ANL for my MS2000.   ANLs are cheap (<$10 for five) compared to Class Ts that can be eye-wateringly expensive.

When Sean was recommending fuses on the negative side, he was talking about catastrophe fuses for entire battery banks, not individual load fuses.   On his recommendation I have a 300A Class T for each of my house battery banks on their negative feed cables, but I'll also use  Blue Sea battery terminal fuses for each pair of golfcart batteries on their positive feeds, plus individual fuses or CBs for each item or circuit.   Can't be too safe!

John

[luvrbus]

So can you or not use a breaker in place of a Class T fuse inquiring minds here

[richard5933]

I am planning to install a Xantrax 1750 Inverter and the manual calls for a 250A Class T fuse. These fuses are quite expensive. Can I use a 250A breaker which is a LOT cheaper.

Thanks

Fred

From what I've read, you cannot just swap the same size breaker for a fuse. They each have different characteristics in how they protect a circuit.

I see the Blue Sea 250A Class T fuse is listed at about $45. Where can you get a good quality 250A breaker for less? Seems to me that if the manual calls for a fuse, then I'd be using a fuse.

[Geoff]

A "breaker" is for AC amps.  A "fuse" nowadays is for DC amps.  Many years ago they made AC fuses, but again they were designed for AC amps.

[bobofthenorth]

A "breaker" is for AC amps.  A "fuse" nowadays is for DC amps.  Many years ago they made AC fuses, but again they were designed for AC amps.

An amp is an amp.

Breakers are commonly used on DC circuits.

[buswarrior]

My big Trace 4024 came as a package with a 250 amp DC breaker box, also branded by Trace.

Happy coaching!
Buswarrior

[richard5933]

An amp is an amp.

Breakers are commonly used on DC circuits.

It's not the amps. It's not the volts. It's the arc. An AC circuit doesn't produce nearly as large of an arc when the circuit breaks due to the way the current alternates. A DC circuit produces a much larger arc when the circuit breaks, and this is what causes the damage to the contacts in the switch or breaker. The larger arc is why the same switch may have a 100-amp rating on AC and only a 10-amp rating on DC. The increased arc from the DC circuit can cause the contacts to pit, wear, or actually stick together. For a circuit breaker to function properly on a 250-amp DC circuit it would have to be much beefier than one designed for only an AC circuit.

[buswarrior]

Yes, and that's why one chooses a properly rated device for wherever it is going?

Boring work, reading the small print. Thank God for CSA, UL and friends...

Happy coaching!
Buswarrior