Cable entry into Consumer unit

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This consumer unit has a bunch of cables that are rear entry and some that are going through a side entry with cables trunked along the wall. I think the current side entry is using a rubber/silicone type seal.
If I were going to use another knockout, can I use one of these for the cable entry?

The cables would be coming down trunking again. Does the above gland require intumescent sealant too?

Thanks in advance.
 
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The cables would be coming down trunking again. Does the above gland require intumescent sealant too?
There's nothing in the ('silly') regulation requiring domestic CUs to be made out of 'non-combustible' materials that requires any 'fire containment' (a metal CU full of 12mm holes is 'compliant'!), so there is never a need for intumescent seals around cables entering the CU.

Kind Regards, John
 
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Can I clarify please. Is the objective to contain the fire within a metal CU best practice but not a regulation?
 
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Can I clarify please. Is the objective to contain the fire within a metal CU best practice but not a regulation?
Daft though it may be, it's clearly not a regulation/requirement.

As for 'best practice' I suppose one could not criticise anyone who wanted to install a CU such that it could 'contain' a fire for at least a while, but I'm not sure than (m)any people go out of their way to achieve that.

Others will undoubtedly have views about 'best practice'.

None of my plastic-cased fan heaters (necessarily full of holes) would 'contain' a fire!

Kind Regards, John
 
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but I'm not sure than (m)any people go out of their way to achieve that.
Was at my sister in laws yesterday and like you do, asked to take a look at her consumer unit. This was installed 4 years ago by an “electrician” she tells me. It’s under the stairs.
C5096024-6986-44C8-A9BA-1249AFAABAE5.jpeg

Am I wrong to think that there are so many instances of similar work and have passed all the required checks, etc. It has a gaping hole where those cables are entering.
 
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That looks a lot more than 4 years old! Did she get an installation certificate and a building regulations completion certificate?

The holes are too big and do not meet the IP requirements. Did he/she cut them with their teeth??
To meet requirements they should be tight around the cables. A squirt of silicone would make them compliant.

But there may be more horrors to consider....
For starters, and just at a first glance, the two lighting circuits do not appear to be RCD-protected. 4 years ago was the time of the17th edition and from that point most domestic installations required RCD protection on all circuits due to cable depth requirements.
 
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I watched and listened to a lecture on the new amendments, and it was an eye opener to me, I had read about escape routes, but I had not understood what was mean, the escape route is the non decorated stair way with no carpets, often made of concrete where the only electrics are the lights required to see ones way out, the standard corridor is not considered as an escape route.

I think this is repeated many times, what was in the mind of the people writing the regulations is not always what the people reading the regulations think it is telling them.

This is not just electrician regulations, seen it were local authorities have published documents saying how TRV heads on radiators form zones, and there is not requirement for any other zone valves.

It seems all down to English comprehension, do you remember doing it at school, now actually taught as "Coms" in collages, although not sure even the lecturers are sure they are getting it right.

This has caused problems in Wales as official documents need to be available also in Welsh, and to translate BS 7671 would be some mammoth task to ensure no mistakes, it not as simple as translate word to word as a small house in Welsh would be normally called a toilet in English.

These pages see where we try and read the regulations and laws and interpret them to work out what is allowed, but in many cases it is not one book or regulation but many which interact with each other. So we have the IP rating, which decides a finger is 12 mm diameter, (IP2X) and a wire I think 1 mm diameter (IP4X) and from the top need to stop a wire and from sides and below a finger.

The consumer unit does not want to give you a shock when you touch it, but it also wants to retain burning parts for a reasonable time, the metal consumer unit powder sprayed the coating is not very thick and can easy be damaged, so there is a trade off, plastic is less likely to cause a shock when you touch it, but metal less likely to allow burning parts to escape, the metal is bonded to earth, but since the RCD is often within the consumer unit the CU itself is not RCD protected, only parts outside the CU have RCD protection, so we should isolate else where before going into an distribution unit in case a fault has caused there to be a loose wire.

We have seen this knee jerk reaction before, where we at one time even bonded metal window frames, we are in essence looking at a risk assessment, and to decrease the risk or fire which in turn increases the risk of electric shock is a balancing act.

Using silicon sealant can help make the top comply with IP4X but is also retains heat, so you only want just enough, don't go mad with it, common for fuse wire and like to be stored on top of a distribution board, clearly don't want it to fall inside. But in the main it is common sense rather than following regulations to the letter.

We hide behind the regulations, we can claim 'not my fault' when some thing goes wrong, as it complied. My mother never used an electric drill and was in a wheel chair, so having RCD protection because a wire was less than 50 mm deep did not make it safer for her, RCD so if she dropped the kettle in the sink yes, but not in the wall, so I would not expect the lack of a RCD on lighting circuits will really cause much danger.

However as a primary school kid I poked my fingers up the light socket where the bulb was missing to feel what was inside, did not repeat it, but learnt the hard way electric bites, you can get BA22d lamp holders where the pins are not live until bulb fitted, but rare, and called BA22d because the hole is 22 mm across, which is clearly more than the 12 mm of the IP rating, we also have E27 and E14 again both over 12 mm and rarely have safety features to stop you getting a shock, in the ceiling OK, but with a table lamp, clearly a danger once bulb is removed. MK do make a safety BA22d lamp holder (Logic Plus) where "Automatically shield contacts by means of a shutter when the lamp is removed" but not normally found with pendent lamps, not looked to see if available with E27?

So common sense, with a CU above the kitchen door unlikely a toddler will stick its fingers in the holes, under the stairs in what I always called the glory hole, made famous by Harry Potter, then yes likely toddler could play with it.
 
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So common sense, with a CU above the kitchen door unlikely a toddler will stick its fingers in the holes, under the stairs in what I always called the glory hole, made famous by Harry Potter, then yes likely toddler could play with it.
It's always struck me that those who invented the rules about IP requirements for enclosures probably hadn't heard of toddlers, since those rules only require an IP rating guaranteed to be proof against toddler's fingers on the top surface of the enclosure, which is the surface the toddlers are least likely to be able to get at!

Kind Regards, John
 
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For starters, and just at a first glance, the two lighting circuits do not appear to be RCD-protected
Is it possible that the MCB’s next to the main switch are actually on the busbar connected to the RCD but someone has decided to leave some of the blanks midway?
 
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Is it possible that the MCB’s next to the main switch are actually on the busbar connected to the RCD but someone has decided to leave some of the blanks midway?
Not at all likely. It’s possible, but that would put all circuits on one RCD (not correct) and you wouldn’t ever do it like that. It’s set up as the way CUs were installed in 16th edition and that makes that board being installed between 1992 and 2008.
That’s assuming whoever did that complied with the regs in force at the time and didn’t just buy a second hand board off eBay and charge for a new one.
As Jonny Nash said
There are more questions than answers.
 
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Not at all likely. It’s possible, but that would put all circuits on one RCD (not correct) and you wouldn’t ever do it like that.
Well, there could theoretically be two RCDs if both were connected to the main switch by cables (as in a 'high integrity' CU), rather than one being connected via a little busbar - but, as you imply, only an idiot would "do it like that" :)

Kind Regards, John
 
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Well, there could theoretically be two RCDs if both were connected to the main switch by cables (as in a 'high integrity' CU), rather than one being connected via a little busbar - but, as you imply, only an idiot would "do it like that" :)

Kind Regards, John
That is exactly how my Square D was designed:
Main isolator on the left, From there:
Busbar heading right for MCB's, and
Pair of tails to: RCD and short piece of 2P busbar to 2nd RCD. First RCD's 'load' busbar headed left for MCB's & 2nd RCD's 'load' busbar headed right for MCB's.

3 Neutral leads to appropriate neutral bars of course. IIRC the busbar was supplied in a single piece to cut to appropeiate lengths

Something like this:
1653424753049.png
 

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