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solarfamily avatar image
solarfamily asked

Ground to house panel? Multiplus

Setting up a basic, non-solar (at this time) powerwall for home to cover short term power outages.

Entire setup is basic at this point:

  1. Multiplus 24/3000/70. Firmware updated. Mounted to basement wall. *Not grounded yet.*
  2. bigbattery.com 24V A123 2.45kWh battery (one now, but will expand)
  3. Heavy gauge plug from AC-IN on Multiplus to simple 20amp wall outlet next to home electrical panel (13A limit set on multiplus). Then, heavy gauge extension cord on AC-OUT to power fridge and misc. essentials during power outage.

Idea is to charge off grid power and use only for essential during outage.

Problem: If battery is plugged in, home circuit breaker trips within seconds. *Multiplus is currently not grounded, so I understand this may be a key factor.

Question 1: Is the tripping likely due to case not being grounded? Or, is it surging too many amps on initial charge (note I have it set to 13A IN limit, but still trips) and I simply need a bigger breaker?

Question 2: Where should I safely ground it? Wouldn't it be natural to simply pop the home electrical panel and run grounding wire to main panel ground bar?

Thank you for your input; this is an awesome community!

installation
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2 Answers
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wkirby answered ·

I think you really need to get some expert eyes on this.
Someone needs to figure out why the breaker is tripping - whether it is due to a ground fault or if it is an overload.

The unit is supposed to be grounded for sure. How this is done is difficult to answer as regulations differ according to local rules.

My best advice would be to consult a local electrician to help diagnose and do the wiring safely and to local regulations.

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ejrossouw answered ·

@SolarFamily Firstly, typically only qualified electricians can install new circuits/breakers so ensure you don't fall foul of the building regulations ;) (Individuals can however add equipment to existing circuits under some circumstances.)

Note, I am not an electrician, but some basic ideas / things you can check if you are 100% comfortable.

1. Is the battery grounded and to where?

2. In a static home installation, the ground on the MP ACIN will typically be adequate, but check local rules.

3. Don't discount the possibility of a faulty breaker. I installed bnib devices that tripped erratically and the problem was solved with a replacement.

4. You can test the ground loop theory by turning off the relay, but do so at your own peril and plse DON'T do it to solve the problem either. Risk to lives, invalidated insurance, the law etc. jumps to mind.

5. Consider getting the electrician to wire in a critical loads switch board and bypass if this will be a permanent installation.

6. Limit the charge current in DVCC to see if that helps.

7. Ensure the firmware on the multiplus is up to date.

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