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MCB/RCBO/RCD/Fuses - Periodic inspection

Discuss MCB/RCBO/RCD/Fuses - Periodic inspection in the Commercial Electrical Talk area at ElectriciansForums.net

Nuno Gomes

EF Member
Hi guys.

A quick question.
- When people do periodic inspection, is it considerad a defect on the intalation if the Protective diveces are no from the same brand?

- In a TP instalation using fuses should the 3 fuses be from the same brand?

I´m almost sure that I've herad that during my course but no being able to find it on Guidance note 3 or BS 7671...

Kind Regards
 

SheffSimon

Regular EF Member
I can think of no good reason why fuses on a TP supply need to be from the same brand. A fuse is a fuse, made to an appropriate standard.

As for different manufacturers mcbs in boards, you see it all the time in industrial installations, and I can see no real problem with it.
 

Andy78

Respected Member
Fuses are made to specific patterns and sizes and are interchangeable across brands.

MCBs and the like are not and are made by manufacturers to fit specific systems. Other brands fitted in can result in poor connections and potentially dangerous situations, I have seen this many times. It is also not to the manufacturer's instructions. It has long been an accepted bodge but it was never right and the current version of the regs has had to finally point this out.

Obviously there are exceptions such as Schneider group brands that are designed to fit and electrium group brands, but the manufacturer's blessing must always be obtained to check.
 

telectrix

Scouser and Proud of It
Respected Member
if there are no compatibility prblems, C3, imo.
 

Nuno Gomes

EF Member
Fuses are made to specific patterns and sizes and are interchangeable across brands.

MCBs and the like are not and are made by manufacturers to fit specific systems. Other brands fitted in can result in poor connections and potentially dangerous situations, I have seen this many times. It is also not to the manufacturer's instructions. It has long been an accepted bodge but it was never right and the current version of the regs has had to finally point this out.

Obviously there are exceptions such as Schneider group brands that are designed to fit and electrium group brands, but the manufacturer's blessing must always be obtained to check.
That was exactly what i had been told... Sorry my lack of understanding but when you are talking about "interchangeable across brands" that means that they should be all from the same brand. Am i correct?

About the fuse i´ve been taught that the materials that they are made off are not exactly the same and that can change disconection time...

Many tanks
 

Andy78

Respected Member
That was exactly what i had been told... Sorry my lack of understanding but when you are talking about "interchangeable across brands" that means that they should be all from the same brand. Am i correct?

About the fuse i´ve been taught that the materials that they are made off are not exactly the same and that can change disconection time...

Many tanks
Sorry, I'm a bit clumsy with my words a lot of the time. I meant fuses are made to specific patterns and sizes and no matter which brand you use they will fit.

Fuse disconnection times/curves are listed as standard in BS7671 so I would imagine that the BS would require standard construction to ensure these characteristics. I'm not entirely sure though.

Here is a fuse compatibility chart to check manufacturer codes against each other if you need.

Untitled - https://www.tlc-direct.co.uk/Technical/DataSheets/HRCFuses/Index.htm
 

Nuno Gomes

EF Member
Sorry, I'm a bit clumsy with my words a lot of the time. I meant fuses are made to specific patterns and sizes and no matter which brand you use they will fit.

Fuse disconnection times/curves are listed as standard in BS7671 so I would imagine that the BS would require standard construction to ensure these characteristics. I'm not entirely sure though.

Here is a fuse compatibility chart to check manufacturer codes against each other if you need.

Untitled - https://www.tlc-direct.co.uk/Technical/DataSheets/HRCFuses/Index.htm
Ok!!! tanks :)
 

spinlondon

Forum Mentor
Hi guys.

A quick question.
- When people do periodic inspection, is it considerad a defect on the intalation if the Protective diveces are no from the same brand?

- In a TP instalation using fuses should the 3 fuses be from the same brand?

I´m almost sure that I've herad that during my course but no being able to find it on Guidance note 3 or BS 7671...

Kind Regards
Type tested DBs have a breaking capacity of 16kA.
Non-type tested DBs have a breaking capacity that is equal to the lowest breaking capacity of the individual components.

As such, if you have a PFC of 4kA and the DB is type tested, no problem.

The use of other makes of components means the type testing is out the window.
You now have to verify that all components have a breaking capacity greater than 4kA.
 

Risteard

Respected Member
The conditional rating is one issue, but it would be quite wrong to suggest that it's the only one. And for domestic type premises a DB should be type-tested (a consumer unit must be type-tested to meet the definition of a consumer unit).
 
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