# 240V 3 Pole Breakers - Cutler Hammer DK3400W



## solarstoresteve (Jul 17, 2012)

Can you backfeed an electrical service panel with a main service 240v 3 pole breaker with a 240v inverter on a 208V three wire service or is a supply side (208v) connection necessary with a 208v inverter?


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## McClary’s Electrical (Feb 21, 2009)

The voltages need to match.


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## TimChaput69 (Nov 14, 2011)

Check the acceptable range on the inverter and the actual voltage where your going to backfeed. Inverters sync with the available service in order to work. Sometimes if the available voltage is low enough or high enough you can get away with it but I wouldn't sell a job on it! Again, check the inverter specs for its operating range and see what you have for actual voltage on site.


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## MDShunk (Jan 7, 2007)

solarstoresteve said:


> Can you backfeed an electrical service panel with a main service 240v 3 pole breaker with a 240v inverter on a 208V three wire service or is a supply side (208v) connection necessary with a 208v inverter?


Wow, that's really touchy. I think the real answer is "maybe", but I wouldn't even attempt it.


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## solarstoresteve (Jul 17, 2012)

My inverter is 240v or 208v but only 2 legs. I am using 9 inverters so I can balance the power. The question is where to attach my inverter breakers on the 240v side of the main breaker or line side tap on the 208v service? What is your though on that?


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## McClary’s Electrical (Feb 21, 2009)

The more I read your original post the more it confuses me. Can we start all over?


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## TimChaput69 (Nov 14, 2011)

??????


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## guest (Feb 21, 2009)

I see a big boom in someone's future. 

Generally, the user's equipment may not like the voltage drop in this case, and it sounds like you want to feed a single phase inverter into a three phase panel. :no::no::no: It will not work and you will damage any three-phase connected equipment. 

Bad news all the way around.


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## solarstoresteve (Jul 17, 2012)

The inverter can be set up for 240v or 208v, only two legs. 
CSI (California Solar Initiative) and the inverter mfg both have approved this application of the inverter.
We use 9 inverters to feed 6 X 3 Pole 40Amp breakers in a combiner/sub panel.
or 9 inverters to feed 9 X 2 pole 40Amp breakers.... 
Again, the question is can we backfeed the sub panel on the 240v side of the main breaker? 
_I think not but our electrical engineer should have an answer this AM._


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## TimChaput69 (Nov 14, 2011)

Sorry bro, not really getting it at this point. All solar I've done we just used proper sized inverters....meaning if we were going to make 3 phase power we would use either larger inverter( size of a refrigerator ) or combine strings a different way. Sounds almost like someone is trying to make something work that they had on hand. But I could be completely wrong ;-)


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## guest (Feb 21, 2009)

solarstoresteve said:


> The inverter can be set up for 240v or 208v, _*only two legs. *_
> CSI (California Solar Initiative) and the inverter mfg both have approved this application of the inverter.
> We use _*9 inverters to feed 6 X 3 Pole 40Amp breakers*_ in a combiner/sub panel.
> or 9 inverters to feed _*9 X 2 pole 40Amp breakers*_....
> ...


You are in wayyyy over your head and you need to get a qualifed EC involved before you either kill someone or cause some very expensive damage or start a fire. 

Your continual use of improper terminology tells me you have no clue as to what is required here. 

Then again, I could be wrong, it wouldn't be the first time. But from your posts.......

So again, to answer your question: NO!!



TimChaput69 said:


> _*Sounds almost like someone is trying to make something work that they had on hand.*_ But I could be completely wrong ;-)


My thoughts exactly and I'm willing to bet you are not wrong.


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## nolabama (Oct 3, 2007)

solarstoresteve said:


> The inverter can be set up for 240v or 208v, only two legs.
> CSI (California Solar Initiative) and the inverter mfg both have approved this application of the inverter.
> We use 9 inverters to feed 6 X 3 Pole 40Amp breakers in a combiner/sub panel.
> or 9 inverters to feed 9 X 2 pole 40Amp breakers....
> ...


No you cannot, get the correct inverters.


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## solarstoresteve (Jul 17, 2012)

My engineer said you stupid....!#@$ that is not the same 240 that you are used to. Delta - Stinger - ....something!!!

So we are using the 208v outputs to the 208v three phase breakers in sub panels. The rest is basic from there, ..I guess.


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## jstrick2 (Jun 29, 2012)

solarstoresteve said:


> My engineer said you stupid....!#@$ that is not the same 240 that you are used to. Delta - Stinger - ....something!!!
> 
> So we are using the 208v outputs to the 208v three phase breakers in sub panels. The rest is basic from there, ..I guess.


 
Anyone got a translator?


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## nolabama (Oct 3, 2007)

Ifin he hooks up a 208 inverter to a 240 high leg be wont need no engineer. Or translator.


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## McClary’s Electrical (Feb 21, 2009)

solarstoresteve said:


> My engineer said you stupid....!#@$ that is not the same 240 that you are used to. Delta - Stinger - ....something!!!
> 
> So we are using the 208v outputs to the 208v three phase breakers in sub panels. The rest is basic from there, ..I guess.


 

Let me tell you something. There's no such thing as 240 that we're not used to. We're professionals that have seen it all. High leg services are VERY common in the city of Richmond. So tell me, if you're using two pole breakers, how are you gonna feed a single leg that is 208 volts TO GROUND. Let's hear your answer to that.


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## McClary’s Electrical (Feb 21, 2009)

Ok, since you think we're idiots, there's only one way to shut that up. Here's how Delta services can be configured. In a Wye secondary, as you know you have three voltages out of phase by 120 deg.If you measure to the neutral from any phase you get 120 volts. If you measure phase to phase you get 208 volts. Now if you remove one of the three transformers; you still get 120 volts line to neutral on two phases. You can still read 208 volts across the two lines that are left. if you reverse the secondary connection on one of the transformers, you move the phase angle through an angle of 180 deg. The phase displacement on a wye circuit is 120 deg. if you rotate that line 180 degrees (By reversing the connections) you end up with 300 degrees. The difference between 300 deg. and 60 deg. is whether you measure the inside angle or the outside angle. Now you still measure 120 volts from line to neutral from either line, but from line to line where you previously read 208 volts, you now read 120 volts because the phase angle has been changed. You now read 120 volts line to line as well as line to neutral. You now have a corner grounded 120 Volt Open Delta bank.There is not much call for 120 Volts Delta three phase so change the internal transformer connections back to 120/240 volts. Now you have a corner grounded 240 Volt Three Wire Open Delta. Much more usable. Do you have single phase loads? Move the ground connection from the corner to the center tap of one of the transformers and from there run a neutral to the service head. You now have a four wire Open Delta with 120/240 Single Phase as well as 240 Volt three phase.


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## guest (Feb 21, 2009)

McClary gave the best explanations as to why this will never work. 



solarstoresteve said:


> My engineer said you stupid....!#@$ that is not the same 240 that you are used to. Delta - Stinger - ....something!!!
> 
> So we are using the 208v outputs to the 208v three phase breakers in sub panels. The rest is basic from there, ..I guess.


The rest is that you are gonna damage the customer's equipment by undervoltage and improper connection, and you are most likely gonna destroy the inverters too. But hey, don't listen to the EC's who know WTF they are talking about and have at it. :no::whistling2:

Your engineer needs to go back to school and learn proper electrical theory and the differences in various service configurations before he gets someone killed. 



nolabama said:


> Ifin he hooks up a 208 inverter to a 240 high leg be wont need no engineer. Or translator.


Just a fire department and maybe some ambulances.


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