sweyn avatar image
sweyn asked

Thickness of Lynx Distributer green GND cable.

In this circuit diagram, what gauge cable does the green wire marked “GND” from the Linx distributer need to be relative to the various other cables?

Also, why?


Groundinglynx distributor
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1 Answer
Alexandra avatar image
Alexandra answered ·


It has to be the equal to or larger than current conductors as it has to be able to carry the full fault current of the system as far as I understand.

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sweyn avatar image sweyn commented ·

So equal or thicker than the battery cables to the Lynx BMS?

I‘m confused as to why that would be necessary. The full fault current is surely only in the battery circuit, and with fuses everywhere, what are we trying to achieve by also giving that path to ground?

If I run a cable from an isolated battery positive terminal direct to earth, nothing will happen so what is the advantage of lining the negative to earth with such a large cable?

I find DC earthing very confusing…

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Alexandra avatar image Alexandra ♦ sweyn commented ·

So do I. And regulations also govern alot of it. And those are as clear as mud as well.

It needs to big enough to blow fuses or trigger safety devices.

Mobile or fixed install also changes things.

Some batteries are negative grounded.

Sometimes only the case of the battery.

Some systems are not grounded at all.

Lynx manual 6.2.3

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southsideph avatar image southsideph sweyn commented ·
My understanding, the reason for earthing to the negative bus is to protect against an inverter fault whereby AC could appear on the DC. I don't know for sure, just what I have been told is the Earth wire should be thick enough to take the full fault current at the AC voltage not the DC e.g. Multiplus 3000 (3k3) / 230V = ~ 13A 1.5 - 2.5m2 for 10K 43A 10mm - 16mm2

Would be interesting to know officially

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sweyn avatar image sweyn southsideph commented ·
That would make sense. I’m going to use a 16mm2 cable, but my multiplus is only an 800, so could probably get away with a lot less.
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