skyking1
Solar Enthusiast
second the trough suggestion. Easy to avoid parallel paths and keep it all civil.
Critical loads panel with 2 power sources, interlocked. Do I have the neutrals wrong?
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timselectric
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The reason why you don't want a parallel neutral path is because both paths will share the neutral current.
If you switch the hots to bypass the inverter, to work on it.
When you try to unhook the neutral in the inverter, you will be handling a conductor that is carrying current.
If you switch the hots to bypass the inverter, to work on it.
When you try to unhook the neutral in the inverter, you will be handling a conductor that is carrying current.
skyking1
Solar Enthusiast
Love the idea of both neutral and EGC in a polaris(s) in the gutter.
Rokkerhead
New Member
Thanks for the help! I think I finally have it understood. I was trying to cheap out with the interlock. But at the total cost of this system, a couple hundred bucks for a 3 pole disconnect to do it right is insignificant in the long run. Much appreciated!
timselectric
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Yeah, if the trough option won't work for you, then a 3 pole transfer switch is the next best option.
Rokkerhead
New Member
I’ve been looking all day. I can’t find a 100 amp 3 pole double throw transfer switch anywhere. Any online electrical stores I should search?
Three phase switchgear is hard to find rn and crazy expensive. Here’s one for “only” $1,100. Non-fusible, indoor rated.
Rokkerhead
New Member
Yeah. This is the only one I’ve really found. And, yeah, ouch!! I’m not doing that.
timselectric
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Unless you want to spend $2k , I would suggest Ebay.
They can be found for under $1k used.
timselectric
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GFCI's and AFCI's only protect what is on the load side of them.
They aren't affected by the line side parallel neutral. They have no way of knowing what is going on with their source.
Here is a 3 pole automatic transfer switch that might work for you:
NATURE'S GENERATOR 24 space/48 circuit 120/240V NEMA-3R 125A Automatic Transfer Switch NGA12532448W - The Home Depot
Procure an efficient addition to your kitchen with this exclusive NATURE S GENERATOR NEMA Automatic Transfer Switch.
www.homedepot.com
timselectric
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A trough would be so much better for many reasons.
Rokkerhead
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Does the trough setup eliminate the concerns of the parallel neutral issue?
timselectric
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Yes, it allows the use of a single neutral, tapped to each item.
skyking1
Solar Enthusiast
timselectric
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That'll do fine.Use an insulated Polaris connector like this?
skyking1
Solar Enthusiast
I figured that was the ticket. One for neutral one for grounds. Make trees and not loops 
$71 and saves so much monkey motion.
$71 and saves so much monkey motion.
While true, the voltage when you make the disconnect will be tiny since the other path is a solid connection and is rated to take the entire neutral load. We're talking millivolts.
In other words, there is no actual danger here. You aren't disconnecting a live hot or something like that. Regulations and physics don't align in this case.
There will still be shared neutral currents even with the trough and single point neutral bar. The inverter grid neutral and the inverter load neutral both run from the inverter to the single point neutral connection. They will share current since they are tied together at the inverter and at the single point neutral bar. So you can never achieve the idealism of neutral currents always go exactly with their line currents.
For our setup, we ran the bypass neutral with the bypass wires to the critical panel and the inverter load neutral to the critical load panel. The critical load panel has interlocked breakers for the hots. All inspected and passed, for what it is worth.
I have no concerns about the safety or functionality of the system as wired.
Mike C.
If you have any critical load panel bypass capability, you are going to make a loop with the inverter grid neutral and the inverter load neutral.I figured that was the ticket. One for neutral one for grounds. Make trees and not loops
I'd like to see a diagram that shows otherwise.
Mike C.
skyking1
Solar Enthusiast
I decided against the bypass capability. I won't have any loops.
timselectric
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For the ground, just use a ground bar. $10I figured that was the ticket. One for neutral one for grounds. Make trees and not loops
$71 and saves so much monkey motion.
I predict that will be something you will regret. Any time you have to do anything to the inverter, you lose power. For example, a firmware update.
These loops are harmless despite the concern people show over them.
Mike C.
timselectric
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You will probably regret not having that option.
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