For you electrical guru's???

jackhartjr · July 03, 2011, 09:16:30 AM

Hi folks, I am going to be driving a show truck for the next 15 months while the owner goes to the Middle East for our Uncle Sam.
I have a 1500 watt inverter, typical truck stop kind. I am using 4 guage wire from the battery to it. How is the best way to protect it fuse or circut breaker wise?
I have had in the other truck with a 100Amp in line fuse. It worked OK but I noticed it got hot the last time the fuse blew. (Blew twice in a year.) I run a refrigerator and microwave on it. (Not at the same time.)
One of our guys uses a 150Amp fuseable link with his.
Thanks in advane!
Jack

Sean · July 03, 2011, 11:06:03 AM

Jack, for that size and type load I would use an ANL fuse. Cheap and widely available. Get the covered-type holder for it so nothing shorts against it.

-Sean
http://OurOdyssey.BlogSpot.com

Lin · July 03, 2011, 11:23:02 AM

If you use that type of holder, don't forget to buy a couple of extra fuses. Of course, the hard part will be remembering where you put them when you want them. I am now wondering where mine are.

babell2 · July 03, 2011, 11:32:35 AM

Bussmann makes a high amp circut breaker. This one is rated at 150 amps.

Brice

Sean · July 03, 2011, 12:08:26 PM

Lots of companies make high-amp circuit breakers. I do not recommend them to protect inverters. Generally they do not trip fast enough (and an ANL is right on the hairy edge -- if you told me you had an expensive Trace or Outback rather than a truck-stop model, I would have told you to go to Class-T).

Knowing what type of fuse or circuit breaker to use for a given application is an extremely complicated endeavor. It is not as simple as looking at ampere ratings in a catalog. You need to understand the dynamics of the circuit under protection as well as the full specifications, including trip tables and arc interrupt ratings, of any circuit protectors you are considering.

In many cases, the device manufacturer will have done this for you. For example, many high-end inverters specify Class-T fuses only. Using anything else, especially a circuit breaker, will void the inverter warranty.

FWIW.

-Sean
http://OurOdyssey.BlogSpot.com

jackhartjr · July 03, 2011, 01:15:39 PM

Thanks for the replys folks!
What size shoule I get for the 1500 watt inverter. And where is a good source or two?
Jack

HB of CJ · July 03, 2011, 01:44:22 PM

How big is the microwave? They surge a bit when starting up, as might also the reefer, but probably much less. How long is your number 4 wire? What kind of ground are you using? What other stuff may be running when the micro starts and runs? How much stuff will you be adding later? Lights? Sound sytems?

If you can add all it up, then add in a fudge factor for future expansion, then you can determine your wire size. Will a number 4 wire be big enough? Micros AND invertors like very low voltage drops when starting. You will need a fuze type and size that will handle the surge AND still work long term. HB of CJ (old coot)

Sean · July 03, 2011, 02:43:21 PM

Quote from: jackhartjr on July 03, 2011, 01:15:39 PM
... What size shoule I get for the 1500 watt inverter.

Normally I would go with whatever the inverter manufacturer recommends. However, your 1,500-watt inverter probably has a surge capability between 2,000 and 3,000 watts, and #4 can not carry that much.

#4 in "free air" is good for about 125 amps. I would fuse no higher than this number. That would give you the full 1,500-watts your inverter can produce continuously. I would also put a thermal-magnetic circuit breaker on the output, if not already present, of 12.5 amps. That's not an allowable rating for household-type breakers, so you would have to go to a marine style -- not allowable in a bus conversion, but no such rule for a truck.

If you are concerned about the surge capability blowing the input fuse, you'll need to go to a class-T fuse rated at 100 amps. Lots more expensive that way.

Quote
And where is a good source or two?

ANL fuses are widely available. You can get them anyplace car stereo equipment is sold, many auto parts stores, and the more traditional venues of solar equipment vendors and marine chandleries. Google will turn up thousands of hits. Make sure whichever one you get has a 5,000-amp arc interrupting rating, as lower values (2,500-2,700 amps) are common.

-Sean
http://OurOdyssey.BlogSpot.com

jackhartjr · July 03, 2011, 02:51:08 PM

The surge is indeed 3000 watts.
The mircrowave does not seem to surge, it cranks to 800 to 850 watts and stays there. The fridge surges for a quarter second, (I know this looking at the LED indicator for output) at 900 watts then goes down to 60 to 70 watts.
I unplug the fridge when using the microwave.
I hear the fridge cycling throughout the day through the CB radio, it is comforting knowing it is working!
Thanks for all of the advice. I will have the shop install it in a week or so. Now I can go get some parts.
Oh, and the run from the battery to the inverter is 6 feet. I may can make that 4 feet if needed.
Should the fuse be next to the battery, or at least 18 inches away as someone said?
I will post photos of the truck next week. It is indeed a show truck!
Jack

jackhartjr · July 03, 2011, 02:56:12 PM

Sean, I think there is a fuse on the output built in, I will check to be sure.
Thanks
Jack

Sean · July 03, 2011, 03:00:10 PM

Quote from: jackhartjr on July 03, 2011, 02:51:08 PM
... the run from the battery to the inverter is 6 feet. I may can make that 4 feet if needed.

Shorter is always better, as there will be less voltage drop. Also, if you have not already installed this wire, you might see if you can go instead to #2, which can be fused at 170 amps, giving you more margin to use some of the inverter's surge capability.

Quote
Should the fuse be next to the battery, or at least 18 inches away as someone said?

The fuse should go as close to the battery as practical. I recommend no further than 7", which is the same as the ABYC guideline. However, considerations of safe access for fuse replacement must also be made.

-Sean
http://OurOdyssey.BlogSpot.com

Lin · July 03, 2011, 03:12:37 PM

My Trace UB2512 calls for a 400 amp class-t or other DC rated fuse. They also give the option for a DC rated 250 amp Heinemann breaker. I do not know why the required fuse would have a higher rating than the alternate breaker. It is something to do with a surge related delay in the breaker?

Sean · July 03, 2011, 09:41:29 PM

Quote from: Lin on July 03, 2011, 03:12:37 PM
My Trace UB2512 calls for a 400 amp class-t or other DC rated fuse. They also give the option for a DC rated 250 amp Heinemann breaker. I do not know why the required fuse would have a higher rating than the alternate breaker. It is something to do with a surge related delay in the breaker?

That's a very old product and I can't access a manual for it. I'd need to know exactly which model breaker they are recommending; Heinemann made many styles. They are perhaps best known for hydraulic-magnetic breakers, which can be engineered for very precise trip settings. The principle purpose for the hydraulic element is to induce a specific amount of delay at a given current.

Today Heinemann is part of Eaton and is cataloged along with their Cutler-Hammer product line. Now that Schneider owns Xantrex, of course, you would never see an Eaton breaker recommended in a Xantrex manual, as Schneider will have it's own breaker solution from the Square-D, Merlin Gerin, or Tesys lines.

-Sean
http://OurOdyssey.BlogSpot.com

Lin · July 03, 2011, 11:21:08 PM

The manual listed Heinemann series GJ for 200/250 amp and CF1 for 100 amp. Although I have a Heinemann 250 amp breaker for the unit. I should check to see is it is one of those. It pops almost immediately if an AC unit is accidentally allowed to switch to the inverter, which would seem to be a good thing. As a MSW inverter, it does not do well with that type of load.

Sean · July 04, 2011, 05:41:56 AM

Quote from: Lin on July 03, 2011, 11:21:08 PM
The manual listed Heinemann series GJ for 200/250 amp ...

Again, this is not specific enough, as the GJ series encompasses a wide range of ratings, delays, and trip curves. I would assume it specifies the short-delay, series-trip configuration.

The GJ is a temperature-compensated hydraulic-magnetic type. It is designed to hold 100% of rated current indefinitely, and trip at 125% (for 65v DC models) almost immediately. In between there is a delay curve. Like a Class-T fuse, it has a very short trip on dead short, only a few milliseconds. Interrupting rating is 10,000 amps for DC models.

This is also an enormous breaker, 7" tall by 1.5" wide (3" deep, not including handle), weighing nearly two pounds.

-Sean
http://OurOdyssey.BlogSpot.com