Q & A of the Day - Can BSEN devices from different manufacturers be used together in a CU?

Question: A query has been raised that because of a manufacturer being unable to supply BSEN devices for its consumer unit (CU), can another manufacturer's BSEN devices be fitted, so saving having to replace a complete consumer unit.

Though it is not ideal to mix devices, if devices are designed to a BSEN specification and fitted within a BSEN specified consumer unit, requirements for safety, operation and testing are met. Is that so?

BS7671: 2008 - Part 1, Chapter 13, Section 133 - Selection of Electrical Equipment 133.1.1 - says that every item of equipment shall comply with the appropriate British Standard, and devices do just that. Please can you give advice on the subject?

Answer: It is not recommended to mix different manufacturers' MCBs within consumer units, even if the MCBs both conform to the same standards. This is for two reasons:

1. The design of the breakers themselves could, possibly, have differing busbar connection heights.
2. Fitting breakers from a different manufacturer to the one for which the consumer unit has been designed is not good practice. The consumer unit and breakers will not have been tested together and will, therefore, not comply with the standard for consumer units - BS EN 60439-1.

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