Circuit breaker orientation

[niamhharrison]

Hi,

Does it matter what way I orientate a CB? i.e can I have the source coming in at the top and the feed at the bottom and Visa Versa?
Thanks!

 

[cranky108]

You might want to explain what type of circuit breaker. On some it matters and on others it dosen't.

 

[niamhharrison]

Its a Sprecher and Schuh 110kV Breaker?!
Its quite old and currently it is orientated so that the supply comes in the top and the feed out the bottom terminal. I now need to change the orientation and want to know if its feasible?

 

[waross]

Yes and no.
Historically, The codes have required knife switches to be installed thus:
In a vertical plane,
So that gravity will not tend to close them,
So that movable parts are dead when the switch is open,
And, so that fuses are dead when the switch is open.
I believe that these regulations predate the careers of any and all working electricians.
These requirements imply that the feed must be in the top of a knife switch.
This habit carried over into the installation of breakers.
For switches, top feed was and is the law.
For breakers top feed is a strong tradition. Virtually all vertically mounted, wired, circuit breakers of any size are top fed.
More importantly, the great majority of electricians expect breakers to be top fed.
Bottom feeding a breaker is laying a trap for a careless electrician. I believe that an injury or property damage resulting from a bottom fed breaker is the ultimate responsibility of the electrician, but the breaker orientation is a strong contributing factor.
I have encountered instances where there was a compelling reason to bottom feed a breaker, but the greatest part of these cases may be resolved by mounting the breaker horizontally rather than vertically.
An exception may be a breaker panel with an integral main breaker. It is obvious where the feed is and these panels are occasionally mounted upside down, and the main breaker is bus connected to the loads, not wired.
I can not quote any regulation prohibiting bottom feeding of a circuit breaker, (and in the past, I have searched diligently for such a regulation) but I strongly suggest that in the interest of safety and ease of trouble shooting you look for an alternate arrangement.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jghrist]

Many 110 kV stations have lines that are sources sometimes and loads other times, depending on system conditions. Considering this, I would say it makes no difference whether the source is the top or bottom. I assume these are live tank breakers.

 

[davidbeach]

Bill, if the 'k' wasn't a typo in '110kV', I think your list is a bit irrelevant. Good list for low voltage though.

 

[waross]

This was a classic case of over posting. The 110kV information was posted while I was composing my post.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[davidbeach]

Ain't it grand? I'm sure I didn't take 8 minutes to compose my post, but jghrist's post wasn't there when I added mine. Oh well.