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Main Service Shunt Trip Push Button!

Main Service Shunt Trip Push Button!

Main Service Shunt Trip Push Button!

Hello all,

I was asked to provide a shunt trip push button on the building exterior instead of a main service switch (knowing that the main distribution panel inside the building has a main breaker). This is asked to save cost since the main service is 3-phase 800A and providing a shunt trip push button is cheaper than an 800A disconnect switch. Any ideas on a prefered push button station to serve as main disconnect? a regular push button doesn't sound good since it is easy for any passing by person to shut power off the building and a break glass is also not so good since new glass needs to be installed every time it is activated!!

RE: Main Service Shunt Trip Push Button!

Your statement does not really make much sense or is unclear.

A "Shunt Trip Push Button" would activate the Shunt Trip coil WITHIN an 800A circuit breaker, not REPLACE one! So I'm not clear on what your superiors are thinking they are trying to tell you to do here.

If by chance the plan was to have a main service switch PLUS the 800A main breaker that is in the MDP, then yes, that could possibly be be redundant. But often times there are local codes requiring special ratings and accessibility for that main service disconnect device. Here in North America we call that the "Service Entrance" disconnect. So for example here, if the 800A MDP and it's main breaker were not specifically listed as "Suitable for Use as Service Equipment" (S.U.S.E.), then you would be required, by law, to use an additional S.U.S.E. rated switch ahead of it, despite the seeming redundancy. In that case, adding a Push Button to a Shunt Trip in the MDP would not circumvent that law.

"You measure the size of the accomplishment by the obstacles you had to overcome to reach your goals" -- Booker T. Washington

RE: Main Service Shunt Trip Push Button!

We have a shunt trip button on the exterior of the building. It gets pushed maybe once a year by a prankster, which sucks.

You can get one with a hinged cover, or a break-glass type like a fire pull station.

Best to you,

Goober Dave

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RE: Main Service Shunt Trip Push Button!

If the button is to provide a service disconnect function, the AHJ will have to weigh in on whether it provides adequate visual indication of the state of the disconnect (I doubt it). Or provides a function to 'lock out' the service (again, no).

I can think of a situation where the fire department is responding to a situation in a large building and decides that the service needs to be disconnected. Tennants, unaware of the situation (I've actually worked in such facilities. Large and no alarm system.), just say, "Dam! The power went out." and send someone down to the basement to reset the main breaker.

RE: Main Service Shunt Trip Push Button!

I also have doubts that this pushbutton will fulfill its intended purpose if it is supposed to be replacing an actual disconnecting means, but I would definitely use a break-glass type switch.

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