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Posted By Topic: Commercial MCB

Jul 20 2017 11:13

Hi Guys

Just wondering if anyone is installing domestic series MCB\'s in a commercial situation? Both Schneider and GE do a domestic series and I got told the only difference between them and the others is they are warrantied and go through stringent testing.

They both have the same ratings 6Ka C curve etc so is anybody using them in a commercial setup?

In the past I have used the non domestic type ones but just seeing the price difference makes me wonder if there is any reason I can\'t use the domestic series ones?



Jul 20 2017 18:18

The best people to answer this are Schneider themselves although finding the right person could be a bigger challenge.
The way it was explained to me was that the industrial units were more robust and better sealed to prevent contamination from dust in the commercial / industrial area.
Oh, and they don\'t have the little house symbol on them.

Jul 20 2017 18:30

Found this on the Schneider nz web site.
It gives their view of using their domestic (Domae) range of MCB\'s.

Can Domae MCB\'s and RCCB\'s be used in a 400v residential switchboard?

Yes. They are insulated to 440v.
We only import and supply single pole MCB\'s specifically for the residential market. The 230v rated voltage marking complies with AS/NZS 60898-1 for use in 230v, 230/400v, or 400v systems as per section 5.3.1

The above might be considered manufacturers instructions.

Jul 20 2017 18:56

Thanks mate. I might ring them tomorrow and ask. Also thanks for that information, I couldn\'t find anything on their website I\'ll have to keep looking for it.

Jul 21 2017 07:14

I believe that the Schneider Domae MCBs don\'t have the same level of discrimination as the Acti 9 & older Multi 9 range.

Jul 21 2017 08:09

I have in writing from GE. GE DMS single pole MCB marked with 230V rating are not suitable for use in isolating a 3 phase 400V circuit however the GE DMS single pole MCB marked with 230V rating are suitable for use on 3 phase 400V chassis and busbar systems

Jul 21 2017 11:05

Perhaps they are referring to the rules for motor isolation switches [], eg need to be able to break locked rotor current.

Where a separate compliant isolating switching device is supplied, and the mcbs are solely for overcurrent and isolation of subcircuit wiring, 3 x single pole will be compliant. In most cases isolating switches are not required to be linked.

Voltage rating is not an issue, 2 adjacent mcbs each with 230 V rating to earth (which could be immediately adjacent) will have 460 V between terminals. So as long as the kA and load current ratings are right, there are no compliance issues using \"domestic\" type mcbs on non-domestic installations.

However as Aaron said mcbs intended for domestic are unlikely to have been tested for co-ordination, so that eg in case of a short-circuit on a motor they will operate to protect the cable but the motor and/or starter may be damaged.


Aug 09 2019 18:20

I know this is old.. But I was just working on a 3ph board today which has Domae 230V MCBs.

I was wondering if it was the voltage across the MCB, rather than between adjacent MCBs?

For example, if there was 3 MCBs on a 3ph load, and 2 of them were open, there would be 400V across the contacts of those open MCBs.

Is that the voltage that the 230/250V rating refers to?

Aug 13 2019 10:38

The answer to that will be in the relevant manufacturing Standard