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Join Date: Dec 2009
Location: Coffeyville, KS
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Circuit Breaker Symbol

05/19/2016 3:05 PM

Can anyone tell me what the up arrows and

the rectangle below the arrows

mean on this circuit breaker drawing?

I've driven myself plumb mad trying to find

reference to these in our drawing sets.

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Pathfinder Tags: cad circuit breaker drawing symbol
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#1

Re: Circuit Breaker Symbol

05/19/2016 3:30 PM

From what planet? Possibly shows wiring schematic, the box possibly a contactor or fuse

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#2
In reply to #1

Re: Circuit Breaker Symbol

05/19/2016 3:48 PM

Could MT stand for motor terminal? 1-1-2 tied together and 3-3-4 tied together...

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#6
In reply to #2

Re: Circuit Breaker Symbol

05/19/2016 4:17 PM

This picture is from a panel wirer's drawing. MT is the name of that Breaker and when you look in our panels, there is a sticker with the alpha characters by every device in the control cabinet.

There is a comment below where the submitter nailed it.

Unfortunately, on the drawing, the rectangle was filled in solid black and denoted that AWG 8 was to be used on all terminals. The rectangle on the breakers was not solid so I skipped over this a dozen times.

Thanks all!

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#5
In reply to #1

Re: Circuit Breaker Symbol

05/19/2016 4:12 PM

This planet, it is a panel wiring diagram. Vintage 1970's

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#3

Re: Circuit Breaker Symbol

05/19/2016 3:54 PM

Withdrawn.

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#4

Re: Circuit Breaker Symbol

05/19/2016 3:59 PM

Look for a legend on the drawing. The square defines a specific conductor size that should be used for wiring to those terminals (different from the default wire defined also in the legend), and the arrows say it applies to all the wiring on the terminals it points to. This is common methodology on electrical wiring drawings that I see for switchgear, control panels, and other electrical equipment. For example, it may be "standard" for this design to use #14 wire for all connections unless defined specifically. The square may specify that this wire should be #12, and a different symbol may mean #10 wire.

The device you are looking at is identified as MT. The wires on the terminals go to other devices with identifiers such as MV, etc. (but you probably already knew that). If you look at the terminals at the other end of each wire, you should also see the same square. If not, the designer wasn't very good at keeping consistent wire identification.

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#7
In reply to #4

Re: Circuit Breaker Symbol

05/19/2016 4:22 PM

Thanks PeterT,

You nailed it.

In our legends, the rectangle was solid black and denoted to use AWG 8.

Unfortunately, on the breaker, the rectangle was not solid.

I work for a plant that somehow mysteriously lost most of it's technical drawings way before I started working here. We troubleshoot from panel drawing's rather than schematics. Really sucks, but we are getting better at it.

Recently, we installed new annunciator boards and this forced us to have to redraw the prints. I will be on that little project for some time.

Many thanks.

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#8

Re: Circuit Breaker Symbol

05/19/2016 4:23 PM

The symbol is for a thermal magnetic circuit breaker if that helps...

https://quizlet.com/2781709/electrical-wiring-diagram-symbols-flash-cards/

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