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Designing Your Installation
975-0128-01-01 3–7
Calculating Fuse/Circuit Breaker Size
Because your batteries can provide thousands of amps of short-circuit
current, you need fuses or circuit breakers that can safely withstand the
short-circuit current that the batteries can produce.
To select the correct fuse type and size:
1. Determine the total short-circuit current rating for your batteries. For
example:
• If you are using one battery to power your inverter and its short-
circuit current rating is 500 A, the total short-circuit current rating
is 500 A.
• If you are powering your inverter with two 12 V batteries
connected in parallel, and each battery has a short-circuit current
rating of 500 A, the total short-circuit current rating is 1000 A.
• If you are powering your inverter with two 6 V batteries
connected in series, and each battery has a short-circuit current
rating of 500 A, the total short-circuit current rating is 500 A.
2. Once you have determined the total short-circuit current rating of
your batteries, pick the fuse/circuit breaker’s interrupt capacity based
on the short-circuit current calculated in step 1.
3. Choose a fuse/circuit breaker with a correct current rating.
Fuses can be bought at any marine supply store, RV supply store, or
electrical products store.
Important:
For batteries connected in parallel, the total short-circuit current
rating is the sum of the short-circuit current ratings of all of the batteries
connected in parallel. For batteries connected in series, the total short-circuit
current rating is equal to the short-circuit rating of a single battery.
XPower3000.book Page 7 Wednesday, December 10, 2003 6:52 AM