Hawaiian Tie In

Has anybody heard of the term ‘Hawaiian tie in’?

We are a solar company in California. We have been told that 'Hawaiian tie in' is common practice out east.

With a Hawaiian tie in, we remove all load breakers and put a lug kit to feed a sub where we relocate all house loads.

This makes the MSP a ‘supply side’ panel. Even if we leave a main disconnect breaker inside. (Warning plaque - no load breakers allowed)

And because of that (if the situation is needed), we can leave the solar breaker(s) in there. (and they will be a supply side connection – not 120% rule)

All of that does make sense to me. (I just hope we can get the AHJ’s and inspectors on board!)


Would any of you happen to have any code references on this?


Would be much appreciated, Thanks!
 

GoldDigger

Moderator
Staff member
If you leave the main breaker in place and tie the solar breaker to the panel bus, it is not a supply side connection by definition. The dividing line is the Service Disconnect, wherever that may be. So it seems to me the the 120% rule still applies and if the outfeed lugs are at the bottom of the bus you cannot possibly meet the "opposite end of bus" provision.
If you put a lug kit just below the main breaker and the PV backfeed below that you meet the opposite end provision but still have to satisfy 120%.
Can you provide a one line to clarify what you are talking about if I got it wrong?
 

jaggedben

Senior Member
That's not what Hawaiian Tie-in means to me. It means when you have a service panel that is just a main breaker, and a sub inside the house, you insert a new sub in between to create a place to interconnect. I suppose it could just as well mean what you're describing since in any case it's slang and I have no idea where it comes from.

Anyway... :rolleyes::D

What you're describing is a perfectly valid approach, but it has nothing to do with anything being 'supply side'. It is valid because the panel satisfies 705.12(B)(2)(3)(c).* (The use of a subfeed kit instead of a breaker is a bit of a loop hole that is addressed in the 2020 NEC, but as long as there isn't an additional source in the main it's not much of an issue.)

*2017 NEC reference. 2020 numbering is different.
 
So what we are trying to do in certain situations, is to use this method instead of an MPU/wall repair, PGE scheduling, etc.

We were told by SolarEdge that this 'Hawaiian tie in' method is common out east.

The new Energy Hub backup interface (smart transfer switch) must intercept the 'line side' in order to give 'whole house' backup.

They told us that the Hawaiian tie in creates a 'line' side feed to the backup interface and then from there, we can relocate house loads into a new sub.

Some MSP's don't have a disconnect breaker, but some do. (see attached line diagram and #14 warning plaque (no load breakers allowed)

We are expecting some AHJ's and inspectors to push back and are looking for some code references in advance to help explain.

P.S. If it's an MSP that has a disconnect breaker, isn't that disconnect breaker already 'line side'? So with no load breakers, isn't the 'lug sub feed' also line side?
 

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jaggedben

Senior Member
Hmm, you can't remove the service disconnecting breaker from the meter/main. Nor do I see in the line diagram why you'd want to. Something's not adding up.

If the meter/main main is just a breaker (no panelboard) then you just feed the SolarEdge hub with it.

If the meter/main has a distribution panelboard then you relocate however many loads necessary, but always leave the main breaker, which does not count.

Read the code section I referenced above.
 
Yes the MSP that has no disconnect breaker, but just a large breaker (or two) that feed house sub, that is a supply side breaker that we can use to feed the backup interface and it is a supply side connection.

However in a situation where there is a buss bar for loads with a disconnect breaker, they are telling us we can remove all load breakers and put a warning plaque (no load breakers allowed). Basically turning the MSP into a large junction box.

Leave the disconnect breaker in there of course.

But with no load breakers, the sub feed lug becomes a supply side connection from what they are telling us.

Does that make sense?
 
And so if that makes sense, you could also do the same thing in a different situation.

Not for transfer switch, but for a situation where you need 120A's of solar on a 200A MSP.

You could remove all loads, put the warning plaque, relocate all loads to a new sub fed with a lug.

The MSP no longer has load breakers, but you put your solar breakers in there. (supply side connection)

All loads in a new sub fed by the lug.

Does this make sense?? (this is what they are telling us)
 

jaggedben

Senior Member
Yes the MSP that has no disconnect breaker, but just a large breaker (or two) that feed house sub, that is a supply side breaker that we can use to feed the backup interface and it is a supply side connection.
...
The one or two breakers are the service disconnects. That's what makes them supply side connections. I was pointing out that the line diagram you shared doesn't show this correctly, it only shows a subfeed lug in the main.
 

jaggedben

Senior Member
And so if that makes sense, you could also do the same thing in a different situation.

Not for transfer switch, but for a situation where you need 120A's of solar on a 200A MSP.

You could remove all loads, put the warning plaque, relocate all loads to a new sub fed with a lug.

The MSP no longer has load breakers, but you put your solar breakers in there. (supply side connection)

All loads in a new sub fed by the lug.

Does this make sense?? (this is what they are telling us)
It broadly makes sense, but again, removing the loads does not make it a supply side connection. Read the code reference I offered above. It allows what you're talking about but it is a load side rule, and it is a different rule than the supply side rule.
 
Thank you for that!

This is my whole frustration with them trying to convince us that it becomes a supply side. Because in my mind, that lug feeds loads and you can't get away for it being 'a load' on the buss = 120% rule.

Thank you for helping to clarify my 'gut' feeling that this is a wrong way to intercept the 'line side'.
 

Designer101

Member
Location
California
Occupation
Solar Designer
This is an example of
Hawaiian Tie In.
i haven't understood it fully but looks like its code complaint per 705.12(B)(3B) for sub panel to main panel and 705.12(b)(3)(c), for sub panel, this kind of connection is more conman in 200/200 split type panels which are rated 400A each with bus bars rated 200,200. The lead used to instruct me and i used to do that, i had limited nec knowledge back then. i dont work in that company now.
Guys have a look
 

Attachments

With those split buss panels, the line diagram you show is already connecting to the supply side.

I guess in short, I guess the main question is:

Does removing all loads, and not allowing any future loads, make the panel a supply side??
 

GoldDigger

Moderator
Staff member
What makes the connection supply side is that there are no OCPDs between the connection point and the POCO service conductors.
It has nothing to do with where the loads are relative to the connection point.
 

GoldDigger

Moderator
Staff member
So if I'm understanding you correctly, if we have a panel that has a disconnect breaker, removing loads and putting a sub feed lug still means 120% rule because of that disconnect breaker.

Correct?

Thank you for that.
Correct. But unlike an existing 200A panel that may have either 200A or 225A bus you can choose the new panel to have a 225A bus giving you more headroom.
 

GoldDigger

Moderator
Staff member
Correct. But unlike an existing 200A panel that may have either 200A or 225A bus you can choose the new panel to have a 225A bus giving you more headroom.
The wiring diagram in Post #11 would be a true supply side connection IF the breaker in the rightmost panel, which connects upstream of the main disconnect, were dedicated to PV only. If there are also loads downstream of that breaker is it not supply side.
 

Designer101

Member
Location
California
Occupation
Solar Designer
Ya its not a supply side connection but there the breaker feeding the new 225A Sub panel is derated to 150A to allow 120A backfeed, I think as long as the sub panel is code complaint per 705.12(B)(3)(C), we should be good. whats your say Gold Digger?
 

wwhitney

Senior Member
Location
Berkeley, CA
So if I'm understanding you correctly, if we have a panel that has a disconnect breaker, removing loads and putting a sub feed lug still means 120% rule because of that disconnect breaker.
If your panel has only a main breaker and subfeed lugs, nothing else, then you don't need to use the 120% rule, you can use the "sum of all breakers rule." At least in principle the subfeed lugs should be counted as not more than the main breaker, so it would comply. I should think that would be fine for the pre-2020 NEC; the 2020 wording may not allow it, but if so that's a flaw in the wording.

Cheers, Wayne
 

jaggedben

Senior Member
This is an example of
Hawaiian Tie In.
i haven't understood it fully but looks like its code complaint per 705.12(B)(3B) for sub panel to main panel and 705.12(b)(3)(c), for sub panel, this kind of connection is more conman in 200/200 split type panels which are rated 400A each with bus bars rated 200,200. The lead used to instruct me and i used to do that, i had limited nec knowledge back then. i dont work in that company now.
Guys have a look
The diagram has a supply side connection in the main panel, a 120% rule connection for the next sub downstream, and a sum of breakers connection for the PV combiner panel. So three different rules.
 

jaggedben

Senior Member
So if I'm understanding you correctly, if we have a panel that has a disconnect breaker, removing loads and putting a sub feed lug still means 120% rule because of that disconnect breaker.

Correct?

Thank you for that.
Not fully correct. You can also use the other rule about sum of breakers other than the main breaker. Either one is enough.
 
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