A buyer searching for MCCB is usually trying to stop a bad substitute. Low-voltage distribution gear is specified by the fault level, the current, the poles, and the enclosure it sits in. The notes below are selection criteria for an MCCB. They are not a catalog promise. Confirm every rating on the current datasheet, drawing, or test report for the revision you will receive.
What has to be true of MCCB
Low-voltage distribution gear is specified by the fault level, the current, the poles, and the enclosure it sits in. For an MCCB, start from the duty, then the interface to the rest of the machine or the room, then the document that proves the claim. A lower price that leaves one of those blank is a different product.
MCCB is easy to confuse with Cam Switch. If the quote could be read as either, add the line that separates them: the rating, the fitment, or the standard named below. Link the drawing number to that line so receiving inspection can reject the wrong one.
Numbers that change the quote
| Line | What to write for MCCB |
|---|---|
| Mounting | DIN rail, panel, or a stated enclosure with its IP code. |
| Coordination | What sits upstream and downstream so the combination is selective. |
| Rated current | Continuous current at the ambient inside the panel. |
| Breaking capacity | The fault current the device must interrupt, in kiloamperes. |
| Poles and trip | Poles, curve or trip unit, and residual current if people are protected. |
| Voltage and frequency | The real mains, single or three phase. |
How to compare two offers
Lay both quotes for MCCB on one sheet and line up mounting, coordination, and rated current. If a cell is empty, the offer is not finished. Ask for the missing line in writing. When those match, the honest difference is lead time, the test evidence, and who carries the warranty. Do not average a fully specified MCCB with a cheaper line that omitted mounting.
Documents worth having before the deposit
IEC 60947 is the usual family for low-voltage switchgear. Ask which part of it the declaration uses. The file should name MCCB and the revision, not only the supplier’s homepage. A factory quality certificate such as ISO 9001 can sit beside that file. It does not replace it.
Failures that show up after delivery
- Sizing a breaker from the load current and ignoring the fault level.
- Mixing a person-protection device with a plain miniature breaker.
- Cutting an enclosure and assuming the IP code survived.
On an MCCB, the expensive version of the first mistake is discovering it after the goods are in the crate. Put the rejection condition in the purchase order while the supplier can still restate the offer.
A worked RFQ line
Use this shape, then replace the brackets with your duty: “MCCB — Write current, breaking capacity, poles, voltage, and the enclosure code.” That sentence is a template, not a rating of any brand. If a supplier’s datasheet uses different units, convert them onto this sheet so the next offer can be compared.
Where words like explosion-proof / ATEX belong
Searches often add a constraint to MCCB: explosion-proof / ATEX, or IP67. Keep those on this page. ATEX or IECEx is a certificate for a zone, a gas or dust group, and a temperature class. An IP rating does not grant it. Skip the mark if the site is not hazardous. IP67 is dust-tight plus a defined temporary immersion. It is not a rating for living underwater, and it says nothing about sunlight or salt. If you need a third constraint, add it as another line on the same drawing. A second URL that only swaps the adjective does not give a buyer a second fact.
Related in this section: how to specify Cam Switch.
Questions buyers actually ask
What should an RFQ for MCCB include?
Write current, breaking capacity, poles, voltage, and the enclosure code.
Is a cheaper MCCB the same part?
Only if mounting, coordination, and the documents match. A missing line is a different offer.
Do waterproof, OEM, or IP words need their own page?
No. For MCCB they are extra lines on this specification. Ask for the test or the drawing that gives the word a value.