Stinger leg

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Good guy

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I need to order a 800 amp switch gear it has a high leg. What voltage do they come in are they like disconnects 250,600 etc or do they come 120/208 and so on
 
Jraef

Jraef

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Technically the gear itself does not care, but the breakers do. There are some breakers referred to as “slash rated”, meaning their voltage rating is 240/120V, then there are breakers referred to as “straight rated” that are for 240V. You cannot use slash rated breakers on the stinger leg, you can only use straight rated breakers. So when you buy gear rated for 240V 3 phase 4 wire, there will restrictions against using slash rated breakers on the high leg busbars.
 
augie47

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Some of the ones I have seen lately have factory marking indicating the high-leg. Likely to satisfy 408.3(E)
 
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Carultch

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Good guy said:
I need to order a 800 amp switch gear it has a high leg. What voltage do they come in are they like disconnects 250,600 etc or do they come 120/208 and so on
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You mentioned the term "switchgear". Is there a specific application that you have in mind, where switchgear specifically is needed? Or is this a catch-all term that also includes panelboards? The reason I bring this up, is that panelboards are much more common at the scale of 800A, than switchgear.

As others have mentioned, it is the breakers that would "care" about the difference between 120/208V wye systems,and 120/240V high leg systems, because of the slash rating that limits you to 120V to ground where applicable. The high leg exceeds 120V to ground, so slash rated breakers cannot touch that phase. The alternative is straight-rated breakers, where both the the line-to-ground and line-to-line voltage can be as high as the only voltage rating that is mentioned on the datasheet. It is common that 3-pole breakers are straight-rated, while 1-pole breakers are slash rated with few (if any) exceptions. 2-pole breakers are common in both rating types.
 
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norcal

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Carultch said:
You mentioned the term "switchgear". Is there a specific application that you have in mind, where switchgear specifically is needed? Or is this a catch-all term that also includes panelboards? The reason I bring this up, is that panelboards are much more common at the scale of 800A, than switchgear.

As others have mentioned, it is the breakers that would "care" about the difference between 120/208V wye systems,and 120/240V high leg systems, because of the slash rating that limits you to 120V to ground where applicable. The high leg exceeds 120V to ground, so slash rated breakers cannot touch that phase. The alternative is straight-rated breakers, where both the the line-to-ground and line-to-line voltage can be as high as the only voltage rating that is mentioned on the datasheet. It is common that 3-pole breakers are straight-rated, while 1-pole breakers are slash rated with few (if any) exceptions. 2-pole breakers are common in both rating types.
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How expensive are 240V rated breakers compared to slash rated 120/240V versions? Have not needed one but have been told they are pricey, what brand, plug in, VS bolt on, will affect the price of course.
 
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Carultch

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norcal said:
How expensive are 240V rated breakers compared to slash rated 120/240V versions? Have not needed one but have been told they are pricey, what brand, plug in, VS bolt on, will affect the price of course.
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In Square D's QO series of 2-pole breakers, the QO, QOB, and QOB-VH breakers are slash rated. QO-H and QOB-H breakers are straight rated. Straight rated breakers are more expensive. I'll leave it to you to look up specific examples from your supplier. If there weren't a cost advantage to producing both slash and straight rated breakers, so that slash rated breakers could be significantly cheaper for the majority of applications, I would expect a manufacturer to standardize on straight-rated breakers (which they evidently don't do). Manufacturers don't make a separate product line for 208V breakers, due to the fact that it is more economical to standardize on 240V breakers for both 240V and 208V applications.

The QO example shows "120/240V", "240V", and "120V" on the straight-rated datasheets. By contrast, the slash-rated datasheets only show "120V" and "120/240V" without showing a "240V" stand-alone rating. Neither datasheet elaborates on this for clarification, or spells out "slash rated" or "straight rated". This is very confusing, even if you know to look for this nuance in the rating. I wouldn't be surprised if it were common to find slash-rated breakers installed where they don't belong.

According to this article:
http://ecmweb.com/content/understanding-circuit-breaker-markings

"Single-pole breakers are always slash rated."
"Two-pole breakers can be either slash or straight voltage-rated, whereas 3-pole breakers are all straight voltage-rated."
 
electrofelon

electrofelon

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jim dungar

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ptonsparky said:
Slash rated breakers were installed for years on the high leg. Common enough in older installations. IDR when it started to be Red Tagged by our SED, but I do know it was allowed in the past.
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My 1967 Square D literature shows both 120/240V and 240V 2 pole breakers, so I would assume slash rated breakers were actually never allowed on the 208V leg.
 
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