Type of fuse for inverter?

[RLKBOB]

I'm installing a Xantrex 1800/2900 PSW inverter and have a question or two. First question is does it matter which style fuse I use(class T, mega fuse, ANL)? I wouldn't think it would matter and the only difference I can find is price(the T fuses cost a lot more as do their holders), but I don't know for sure and haven't been able to find an answer searching the net.
Second; I'm using 4/0 cables from the batteries through the fuse to the inverter and I plan on also installing a battery switch so I can isolate the inverter to prevent the no-load amp draw when the MH is not in use and for maintenance in case I need to remove the inverter(easier than removing the fuse or disconnecting all the batteries). I know I need to keep the cable length to a min but the battery switch will only add about 6" to 12". Does anybody see any problems with doing this?

Thanks.

[RV Wizard]

The fuse it to protect the cables between the battery bank and the inverter and therefore will not matter as to "type" used, only amperage. Be sure to keep the total length of conductors the same total length and to put a couple twists in the conductor run. Good luck and keep us posted.

[radams]

Quote:

Originally Posted by RV Wizard The fuse it to protect the cables between the battery bank and the inverter and therefore will not matter as to "type" used, only amperage. Be sure to keep the total length of conductors the same total length and to put a couple twists in the conductor run. Good luck and keep us posted.

Hey, Mike -

You got my curiosity up. What's the thinking behind putting a couple of twists in the conductor run? Haven't heard that one before and always looking to learn.

Bob

[RV Wizard]

Twisting the cables is for this reason:
• RADIO FREQUENCY INTERFERENCE (RFI)--is produced, to more or less an extent, by all inverters. Some brands have less than others, but all have it because it's the nature of the task they perform. (Almost all fluorescent lights create the same interference. So do some TVs.) You may eliminate all or most of it by:

• Locating inverter away from TV, radio, etc. This is usually all that needs to be done. It works well in most RVs since batteries and inverter are in some underneath compartment. (As an aside, fluorescent lights can often be relocated if they interfere. Sometimes, just a few inches or pointing them at a small angle away from TV is enough.)

• Twisting the big cables from battery to inverter. This is a pain in the ass, and can reduce the 10' distance from inverter to batteries since twisting reduces overall length of cable. What twisting does is allow the radiating field from cables to oppose each other and, at least partly, cancel each other out.

[RLKBOB]

Thanks for the input. I'll probably go with a mega fuse and holder since they are the most reasonably priced and seem to be the most readily available.
You say twisting the wires is a pita(agreed, probably impossible with 4/0) but you said it reduces the 10' length. Am I missing something? Twisting them will effectively increase the total length of wire used for a given 'straight line' run. Or are you saying that if the wires are twisted then the 10' maximum needs to be reduced to compensate for the extra wire being twisted?

[rebuilder]

if i read it the post right i think he means your 10ft of wire will now only reach say 9ft and some inches so if your inverter is fixed you would need to have slightly longer cables

[RV Wizard]

Yes, twisting of say a pair of 10' cables will not quite reach a 10' span. It does not have to be tightly twisted. I would say 5 twists in a 10' span to be sufficient in most cases.

[wa8yxm]

I think a "T" fuse is the specified in the owner's manual, As for the MEGA and ANL, I'm not familiar with them.... Thus I can not comment on them.

The prime consideration is low resistance,, The "T" fuse is held in place with nuts and bolts with large contact areas so as to keep it low resistance, Again, i don't know about the others.