Boiler circuit 16A MCB

[Michaelwgroves]

I think this was originally about a missing grommet in a consumer unit and a suggestion this was a fire safety issue.

Were Stroma talking about the IP rating being compromised or suggesting that the consumer unit has to be a perfectly air-tight enclosure?
Obviously gaping holes are not a good thing but my higher concern on an EICR is "can someone access live parts? (C1)" or "can someone access a single insulated cable (C2)"

It's on the back, so IP is not an issue.
My use of the word 'grommet' was sloppy, sorry for any confusion.
Yes it was a gapping hole in the back Stroma were concerned about. They advised using rockwall or fire foam. I prefer rockwall as it's easy to pull in/out for future maintenance.

 

[timhoward]

It's on the back, so IP is not an issue.

My understanding is that unless the surface behind is part of a specifically designed fire compartment (e.g. a riser in a tall building) and the consumer unit rear entry holes have violated this, there isn't an actually requirement to 'seal' the back.
Good practise and preferences might suggest otherwise of course.

So if it were me, I wouldn't code a bonding conductor coming into the rear of a CU through a large hole, in normal domestic circumstances.
Let's see if anyone disagrees!

 

[Lucien Nunes]

It's on the back, so IP is not an issue.

For fingers, no, but ingress protection also deals with dust and liquid ingress. One of the problems of holes in equipment enclosures / switchgear leading into a void or cavity is that they can cause a draught through the unit that fills it with dust as air leaks through the gaps around the front panel components etc.

You mistake the spirit of forums, it's not a place to put others down

Sometimes people worry, until they get to know a poster better, with only a few paragraphs to hint at what the person at the other end knows. Most people on here are pretty good overall at keeping things in perspective. You might remember a few years ago, actually a bit more than that now, when there was a general policy of watching for any chink in the armour and lunging for it. A thing of the past on here by and large, however still a popular pastime on some other electrical forums it seems.

 

[Michaelwgroves]

I received the latest Guidance Note 4 - Protection Against Fire yesterday.

My first observation is it's the first guidance note I've ever known to have shrunk! 12 pages..........

The wording has been updated, but seems to read largely the same, as per below;

“The intent of Regulation 421.1.201 is, as far as is reasonably practical, to contain any fire within the non-combustible enclosure or cabinet and to minimise the emission of flames to the surroundings. Consequently, irrespective of whether option (a) or (b) is adopted, the non-combustible enclosure or cabinet must provide a complete envelope (for example, a base, cover, door and any components such as hinges, screws and catches), as necessary, to limit the risk of a fire spreading from within the consumer unit. All blanks, circuit-breakers and other devices should be contained within the non-combustible enclosure or cabinet.”

I recall Wylex released their fire-retardant membrane around this time in response to the new regulation. Stroma were hot on this at the time, and I was pulled up on it. This is why I purchased the Guidance Note 4 - Protection Against Fire 17th edition. I wanted to read the full text, so I was fully aware.

To me this is clear, all openings, irrespective of the face, should be sealed against fire.