I emailed Iota Tech Support a few days ago on the issue of why the positive-line fuse is required.
My questions (using a DLS-45 as an example):
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" IOTA Product: DLS-45
Question:
Could you explain why a type III circuit breaker is needed in RV applications?
I understand the reverse polarity fuse(s) will blow if polarity is reversed or 12v current draw exceeds 60 amps.
Offhand, I thought perhaps the type III circuit breaker is a backup in case something goes wrong with the DLS-45's fuse system. But if that were the case, I'd think the same logic would apply to non-RV applications.
And why a type III circuit breaker (as opposed to other fuses or circuit breaker types)?
Is that requirement an RV-industry safety requirement or something?"
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The response....
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"A overcurrent protection within 18" from the converter is an RV requirement.
It doesn't have to be a type 3 breaker, we only mention it as an example recommendation.
It can also be a glass fuse, auto fuse, or a circuit breaker."
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I called in this afternoon and the same tech answered. I again asked why the requirement for RVs but not other types of installations and explained why I'm asking. He said he only knows it's a requirement for RVs and speculated it's there because other converters may not have the internal fuses (which could be true but I was hoping for something more definitive).
I also asked if he meant 18" from the battery rather than the converter for the protection. He re-iterated it's the converter. (The manual clearly says battery so I think there could have been some confusion there.)...
(copied from the manual)....
"Recreational vehicle applications require a type III circuit breaker be installed within 18″ of the battery, connecting the battery positive to the line side of the breaker, and the IOTA unit to the load side. Connect 'Chassis Bonding Lug' on the IOTA unit to vehicle chassis or other grounding source"
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