energizing cabin wiring during blackout: ground/neutral issues?

joe luser

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May 5, 2020
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Hi!

I'm building a small solar system (essentially Will's https://www.mobile-solarpower.com/2000-watt-24v-solar-system.html ) The cabin has existing, code-compliant (california) grid power. I'm building it in order to learn things, as well as provide power during frequent grid blackouts. Most times, the solar will be running in parallel and unattached to the grid to provide power to a chest freezer

Clearly, i should be able to run extension cords from the inverter during a blackout. But what about plugging directly from the inverter into a cabin receptacle via a double-male-ended extension cord after opening the main service breaker to the cabin? In order to take advantage of the existing cabin wiring.

My concern here is with neutral and ground.

The cabin is grounded at the service entrance via #4 copper to a pair of standard 8' grounding rods hammered into the earth. The solar system is grounded with the negative post of the battery bonded to this existing cabin ground wire. The inverter (giandel 2000W 24V) will also have its ground terminal bonded to this ground wire.

At the cabin grid service entrance, ground and neutral are bonded together on the cabin side of the main breaker. I'm worried that if I simply connect the inverter receptacle to a cabin receptacle via the double-ended plug, that I will be creating multiple paths to ground from every other receptacle in the cabin? Or potentially energizing the ground wire throughout the cabin? Or? It's confusing.

How do people generally do this? Or is "don't do it" the correct answer? Thanks!
 
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MichaelK

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Mar 21, 2020
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VERY, VERY BAD IDEA!!! Under no circumstances should you ever do this! This can potentially be life-threatening to lineman repairing the grid wiring. Even if you open the main service breaker, mistakes happen, and you could at the least be faced with a serious fine, and could potentially face criminal charges for doing this.

The proper way is to have an electrician-installed transfer switch that toggles between the grid and your own electrical system. That way there would be no possible way that power from your system could energize the grid in a "grid down" condition.

Besides the threat to lineworkers, there's also the threat of having a double-male electrical connection. That is also inherently unsafe.
 

smoothJoey

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Nov 30, 2019
Messages
11,833
Hi!

I'm building a small solar system (essentially Will's https://www.mobile-solarpower.com/2000-watt-24v-solar-system.html ) The cabin has existing, code-compliant (california) grid power. I'm building it in order to learn things, as well as provide power during frequent grid blackouts. Most times, the solar will be running in parallel and unattached to the grid to provide power to a chest freezer

Clearly, i should be able to run extension cords from the inverter during a blackout. But what about plugging directly from the inverter into a cabin receptacle via a double-male-ended extension cord after opening the main service breaker to the cabin? In order to take advantage of the existing cabin wiring.

My concern here is with neutral and ground.

The cabin is grounded at the service entrance via #4 copper to a pair of standard 8' grounding rods hammered into the earth. The solar system is grounded with the negative post of the battery bonded to this existing cabin ground wire. The inverter (giandel 2000W 24V) will also have its ground terminal bonded to this ground wire.

At the cabin grid service entrance, ground and neutral are bonded together on the cabin side of the main breaker. I'm worried that if I simply connect the inverter receptacle to a cabin receptacle via the double-ended plug, that I will be creating multiple paths to ground from every other receptacle in the cabin? Or potentially energizing the ground wire throughout the cabin? Or? It's confusing.

How do people generally do this? Or is "don't do it" the correct answer? Thanks!

Don't use a suicide cord.
Get a generator interlock switch for your panel.
Use a hardwire capable inverter and wire it into the interlocked breaker.
Those typically have a green(ground) wire connected with faston male and female connectors.
Opening that connection disables the neutral ground bond at the inverter.
 
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smoothJoey

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picoglf20w120vrmain.jpg
 

smoothJoey

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an ez generator switch might work for this.

From their FAQ
"Is this switch for the entire house or would you need one for each circuit?
No, the switch is for individual circuits that the consumer feels are essential during a power failure. This is the result of the most economical way to energize “just what you need”. A “whole house” transfer switch of the manual style would cost approximately $600 for the product alone not inclusive of installation and additional parts needed to make the transfer complete." -- https://ezgeneratorswitch.com/faqs/
 

mapguy525

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Apr 11, 2020
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Western Washington
Don't use a suicide cord.
Get generator interlock switch for your panel.
Use a hardwire capable inverter and wire it into the interlocked breaker.
Those typically have a green(ground) wire connected with faston male and female connectors.
Opening that connection disables the neutral ground bond at the inverter.

X2 - don't use a suicide cord.

Need to isolate from grid -when grid fails.

One way of many
Transfer switch or cb interlock kit > to inverter > subpanel > circuits
 
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Markus

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Apr 26, 2020
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From their FAQ
"Is this switch for the entire house or would you need one for each circuit?
No, the switch is for individual circuits that the consumer feels are essential during a power failure. This is the result of the most economical way to energize “just what you need”. A “whole house” transfer switch of the manual style would cost approximately $600 for the product alone not inclusive of installation and additional parts needed to make the transfer complete." -- https://ezgeneratorswitch.com/faqs/
Oops sorry. You are correct.
 

Ampster

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Kenwood, California
But what about plugging directly from the inverter into a cabin receptacle via a double-male-ended extension cord after opening the main service breaker to the cabin? In order to take advantage of the existing cabin wiring.

My concern here is with neutral and ground.
My concern would be with the double male ended extension cable. Others have called them suicide cables.
For a little more money there are many alternatives, some of which have already been suggested.
 

evad

Solar Enthusiast
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Feb 21, 2020
Messages
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Someone makes a bank of double throw switches so that you can power your devices either from the grid or other sources. The sample I saw had six switches. If you only needed one or two circuits you could use three way switches which are just single pole double throw switches.
 

joe luser

New Member
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May 5, 2020
Messages
7
Thanks! Yeah, I suspected it wasn't a good idea :)

It looks like EZ Generator Switch might be very helpful, though. The one circuit in the cabin that isn't easy to energize with an extension cord is the lights. Everything else could be corded. So I could install it on the light circuit and run whatever else I need direct with extension cords from the inverter.
 
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tictag

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Dec 31, 2019
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UK
I know this thread makes it sound like the end of the world is nigh!! But it is only because people have been hurt. It is absolutely possible to do this safely, you just need to be very careful and I would, at the very least, get a qualified electrician to certify the installation - better to be safe than sorry.
 

evad

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Feb 21, 2020
Messages
98
I would think that if you look at the manually operated switches you could find something which is not to costly and would be a cleaner solution. In addition to the switching options which have been mentioned there is a mechanical interlock which locks the main off and allows a two pole breaker to be turned on. If your inverter is 120 volt only you would have to insure the everything you want to power is on the same phase.
 
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