MCB as functional switches??

[GBDamo]

What are peoples thoughts.

From the BYB

“Circuit-breakers and RCDs are primarily circuit-protective devices and, as such, they are not intended for frequent load switching. Infrequent switching of circuit-breakers on-load is admissible for the purposes of isolation or emergency switching. For a more frequent duty, the number of operations and load characteristics according to the manufacturer’s instructions should be taken into account or an alternative device from those listed as suitable for functional switching in Table 53.4 should be employed.”

Are there any MCBs out there where the manufacturer approves their use as functional switches. The few I've read up on don't recommend it.

Had a few MCBs fail where being used as functional switches and would like to rewire via a grid switch arrangement. I just don't like the idea of shop workers going in and out of a DB at will, the door no longer closes and it just don't sit well.

Are there any other points that could strengthen the argument to do this or am I being a bit picky?

 

[Richard Burns]

MCBs are safety protective devices and should be operated within the manufacturers guidance.
Using them as functional switches impairs the safety of the installation.

 

[marconi]

A similar question was posed last December. If you copy and paste -

an interesting idea ,but what do yo guys think

into the top right search box you can read some responses.

 

[westward10]

We used to do work for a major retail chain and this was common practice. The boards were generally Crabtree C50 and the mcbs had colour coded discs fixed below them to indicate the time they should be switched on. So for early morning stock and cleaning work you would switch one colour on to give partial lighting. Some had been operated so many times the toggles were floppy and it is debatable whether the devices would operate under fault conditions.

 

[Adam W]

Common practice with shops is to wire the circuits to be switched via a contactor to a keyswitch by the door, then the shop workers come in, operate the keyswitch and everything is ready to go. Upon leaving they do the same in reverse and all the circuits which need to be turned off turn off in one go, leaving anything like alarms, fridges or computers left on. That way they don't need to touch the distribution board and there is less scope for things being turned off which shouldn't.