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Old 03-27-2012, 03:21 PM   #1
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1973 27' Overlander
East Tawas , Michigan
Join Date: Jan 2012
Posts: 61
Univolt ground cable

Why is there a 50 amp fuse on the ground side of my univolt system ? It is the old style glass inline fuse in a 1973 AS. All the circuits and feeds are fuse protected on the inside of the cabinet, but I have never seen a ground cable with a fuse. This is between the battery and converter. Is it for polarity protection ?

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Old 03-27-2012, 03:38 PM   #2
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1961 24' Tradewind
1969 29' Ambassador
1970 21' Globetrotter
Jamestown , Tennessee
Join Date: Jul 2008
Posts: 1,780
I believe that is called a "catastrophe" fuse so that if a serious short to ground happened in something unfused, like the main line for example it would blow.

Many I have seen are cartridge fuses in old ceramic type holders. The rivets holding them together overheat making for poor contact and no 12 volt power in the trailer.
How necessary they are is a matter of opinion I guess. I have eliminated them in several instances to get some one going who lost their 12 volts on the road

Rick Davis 1602 K8DOC
61 tradewind, plus a few others
13 Ram 2500 TD
99 Dodge TD 577K miles

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Old 03-27-2012, 05:48 PM   #3
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Morrill , Nebraska
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If for any reason the positive battery cable would contact the skin or metal frame of the coach, the negative side fuse would blow. Keep in mind that the battery cable on the positive side has no protection between the battery terminal and the positive side fuse. The positive side fuse does not provide protection on any wire that is up stream of the fuse(s).
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