Wiring a MCCB

Leave the wiring to the contractors.

Please.

If you have to ask, you should not interfere with the electricians.

For you, you should orient the MCCB so that the front of the breaker says "on-off" and not "ɟɟo-uo".

If contacts are identified as, e.g. L1, T1 etc. wire incoming to L (by convention). If contacts are not identified (except by numbers), it doesn't matter - whatever makes for the most direct wiring layout will be best.

Thank you very much

Thank you very much for the clarification

Thank you very much for the clarification

MCB stands for Miniature Circuit Breaker; MCCB stands for Molded Case Circuit Breaker.

Line and Load terminations depend on the building installation topography. Distribution panelboards for all loads may be wired from the top or the bottom depending on the nature of the installation. Typically, molded case circuit breakers are fed from bus bars and are connected either by bolting onto bus bars or connection through stabs on the back of a "bucket" into which the breaker is installed. The main bus bars may be fed from the top, the bottom, or the ends depending on the substation arrangement and the building topography.

Miniature breakers can also be bolted to bus bars, or connected via stabs that are molded into or built into the breaker. In some cases, breakers may be installed into individual enclosures as "stand-alone" installations in which the incoming lines and outgoing lines may be at the top, the bottom, or the sides....again depending on the building topography.

Most MFG's have all cable connections at the bottom now a days. What you need to know is L1, L2 L3 and earth ground, are the main power legs, u, V, W are the legs to the motor. These are the more important wiring concepts. B4 it was 480V 2, 4 ,7 HV, 240 tie wires 2,4,6 together, well you all know the rest. Most drive MFG's I work with today have a common terminal strip they work with now with L1, L2,L3, Gnd, M1, M2, M3 Gnd. Do not mess with the ground, It must be earth grounded. More important than everything.

Dear All,

Thank you very much for the replies . If the MCCB ( without shunt trip ) with incoming are not wired to L1,L2 and L3 , Do they still function normal in interms of protection mainly lost one phase or 2 , short circuit ? Or it may very for different brands?

Talking about "without shunt trip" are you sure you are referring to an MCCB, or are you talking about an Fused Isolator knife switch for a distribution board. On these the input side will be the top and when you open the switch it will isolate the incoming mains from the fuses, for save replacement. the output of these will go to a Buss bar from where the input to the top of the MCCB's will be connected and the bottom will be connected to the devices input cables. Looking at your knowlege I doubt if you will know what part you are talking about.

@kvsrihar, thank you for the photos, it is important for OP to notice that with the line on top and Load at the bottom the MCB / MCCB front writing is right way up. In a DB MCB's/MCCB's will be fed to the top from a buss bar fed by an Isolation Switch and the OP will be taken from the bottom to the different loads. With the Isolator switch in the ON position all the MCB's/MCCB's will be life on the top as the input side.

So what happens with a horizontal mount board. Where is top and bottom then?

I think you'll find line and load are governed by the arc interrupter.

All boards are horizontal mount, may be you meant vertical, that will be right if you lay on your side after a night of drinking, do not want to go to the trouble to get in an argument with you. May be the Queens language has a different meaning to my 3rd language understanding. Never in my career of 44 years or in any EEC EXAM in Ireland, Australia, Germany and South Africa or in any legislation I heard or read any thing else. All DB's have a Incoming feed side and a outgoing supply side. To know the difference the incomming feed side is the one with the cable as thick as your ankle and with leads out as thick as your thumb. That cable will also have an Isilator/Switch that will be away from that board and God forbid that you fiddle arround in that board if you do not know that. Mark your comment "off topic" if it have no substance.

I appreciate you are being polite, but the ladies who contribute to CR4 might know the answer if they were asked1

If you look at this box, it shows the "LINE SHIELD" at the top! If you take the time to actually look at the box in your facility, it should become clear to you that you have no business being in the electrical box. Like Lyn said. Leave the electrical to the CONTRACTORS!

@Original Macgyver, thank you for posting the photo of the local Isolator that will always be the first position for an input to a DB and will feed a Buss from where power to the MCB and MCCB's will come from. That will serve as an Emergency off for a specific area served by a Db with many MCB'S and MCCB's inside, like in the case of fire, because it is also a Lock out device.

The Red Herring fishery is in full production.

He was not asking about distribution boards, nor was he asking about MCBs or fused disconnect switches. He specifically asked about the use of MCCBs in motor starter panels where back feeding of large MCCBs is commonplace because of component arrangement inside of the starter and the preponderance of bottom feed arrangements to accommodate the large stiff conductors.

And the photos are of 150/160Amp frame breakers, which as I said, are rarely used as bottom feed applications. That's because the cables associated with them, being smaller, don't necessitate it. Not so with a 400A or 800A frame MCCB.

Point taken with apology to the group and OP,

from,

Red Herring fisherman.

Under IEC 60947 if the device cannot be fed in either direction it MUST be marked Line/Load. If no markings exist it is presumed to be capable of performing its duties when both forward and reverse fed.

However when installed into a control panel forming an IEC 61439 assembly, it should have been verified that it operates correctly under it's unique assembly style, as you could find the assembly is not capable of clearing a fault or coping with the temperature rise requirements. At this point the manufacturer of the assembly should be supplying instructions on how/where to terminate cables.

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