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On an inverter installatuon, must the positive and negative from the battery be protected by a fuse or is it sufficient for only the positive to be fused ?
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Generally , Yes , on PV type inverters and battery systems - There are exceptions which are/were found in Telecoms situations where the neg battery terminal was earthed then you only fused positive or if positive was earthed then negative fused - Think railways do a similar thing were positive is overhead and the rails are negative and earthed -
7.12.7.5 In addition it shall be recognised that the supply from each inverter,
battery arrangement and PV panel (or identified clustered group), constitutes
a supply, and requires arrangements similar to point of supply, which shall
include switch-disconnection arrangements and shall comply with 7.12.5.
7.15.1.3 The live polarity is the polarity that is not connected to earth (positive
on a negative-earth system, or negative on a positive-earth system); the earth
or "0 V" polarity is the polarity that is connected to earth. -
Thank you GCE.
I notice 7.15.4.1 states that where one of the polarities is connected to earth, all the switch-disconnectors and protective devices shall break the live polarity only. The return circuit shall not be disconnected or broken.
Now one will have to determine if the negative terminal of the battery is internally earthed to the casing before deciding on whether to fuse the negative or not, because we earth the battery casings.Comment
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