# explain a stinger and a high leg



## btr (Aug 29, 2010)

on a delta delta and a delta wye trans. what are they and how do they work/apply to the panel and load?

:001_huh:


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## 220/221 (Sep 25, 2007)

I don't know any technical details. All I know is the street version:

Delta is 120/240 3 phase, Two legs are 120V to ground, one is 208V to ground. All are 240V between them.

Wye is 120/208 3 phase. All legs are 120V to ground and 208 between them.


The rocket scientists here will tell you the rest.


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

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. 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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## Roger (Jul 7, 2007)

Here is an illustration










Roger


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## btr (Aug 29, 2010)

220/221 said:


> I don't know any technical details. All I know is the street version:
> 
> Delta is 120/240 3 phase, Two legs are 120V to ground, one is 208V to ground. All are 240V between them.
> 
> ...


Ok, but the term stinger and high leg.. what are they?


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

btr said:


> Ok, but the term stinger and high leg.. what are they?


 

A stinger would be on a corner grounded delta, and it would be the phase that reads around 190-205 volts to ground. You'll burn equipment up if you land a single phase breaker on the high leg.


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## 220/221 (Sep 25, 2007)

btr said:


> Ok, but the term stinger and high leg.. what are they?


 


> Delta is 120/240 3 phase, Two legs are 120V to ground, *one is 208V to ground.* All are 240V between them.


208 is *high*er than 120 and it prsumably *stings* a bit more on contact.

Marked orange. "*C*" phase on *utility* side, "*B*" phase on *customer *side. Older installations (circa 1960something) will likely be "C" phase on both sides.


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## btr (Aug 29, 2010)

mcclary's electrical said:


> A stinger would be on a corner grounded delta, and it would be the phase that reads around 190-205 volts to ground. You'll burn equipment up if you land a single phase breaker on the high leg.


 
so a stinger is another name for a high leg? We have a delta trans at a job and need to get 120v for other stuff. My boss is telling me we could get a delta wye trans with a stinger.. I know that you need a wye trans to get a neutral, but what does he mean when he is saying stinger/high leg??

thnks


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## Roger (Jul 7, 2007)

mcclary's electrical said:


> A stinger would be on a corner grounded delta, .


No, it would not be present on a corner grounded Delta, look at the illustration, it would only be present in a center grounded winding Delta configuration.

Roger


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## Roger (Jul 7, 2007)

btr said:


> so a stinger is another name for a high leg? We have a delta trans at a job and need to get 120v for other stuff. My boss is telling me we could get a delta wye trans with a stinger.. I know that you need a wye trans to get a neutral, but what does he mean when he is saying stinger/high leg??
> 
> thnks


The term "stinger" is also a term sometimes used for the larger transformer in a center grounded Delta transformer bank

Roger


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## varmit (Apr 19, 2009)

A high leg system with a neutral is not "corner grounded" A winding is CENTER TAPPED (XO) for a neutral point and connected to ground. A corner ground is used on a strait 3 phase, 3 wire Delta system, that has no neutral. One of the phases, normally A phase, is connected to a grounding electrode. The purpose of grounding one phase is to provide a return path to clear a ground fault on the either of the other 2 phases. I would normally only use a solid corner ground on a system of less than 400 amps to avoid excessive fault current. Above 400 amp, a resistance grounding system is needed on a 3 wire Delta system.


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## 480sparky (Sep 20, 2007)

This:










is a _stinger_!


This:










is a _high leg_.


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## Mr Rewire (Jan 15, 2011)

stinger is that little wire on the transformer








easy service call last week fuse dropped out waited 30 minutes for the utility company to come by and reset it


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