Knock out holes on consumer unit

LadySpark · Post by **LadySpark** » Wed Nov 17, 2021 5:24 am

Possibly because I'm female, I seem to be the first choice of little old ladies who need a tiny job doing. Old lady wanted a dimmer switch to replace her light switch. Going to turn off the power, I saw the oddest arrangement that I have ever seen on her consumer unit. It appears to be wired correctly inside but, instead of coming from behind, all the wires separately enter the consumer unit through knock out holes. The consumer unit is metal so comparatively new. It is like swiss cheese with every hole knocked out around the sides and top so that each line or circuit could enter separately. I've never seen this before. Is it a new protocol that I have missed?

My first thought is that it was unsafe as glands had not been used so there was too much clearance around the wires. It is in the coat cupboard approx. 1m off the ground so grandchildren could touch it or the lady could use the holes to hang her umbrella etc.

Now here's the thing - little old lady was paying a couple of quid for a dimmer switch. Rough area of town, area where people are likely to be poor. Honestly I would just put in a new consumer unit to solve the problem, but no way can she pay for that. I'm not ridiculously money-grabbing but it is a huge job for a freebie and I can't see her even stretching to the £100 of materials. On the other hand, I don't feel that I can just walk off and leave a very elderly person with a consumer unit that they can poke their fingers in.

Any ideas? It occurred to me to put a load of glands around the wires to make safe on the cheap but that is a lot of work and will look ugly with my name on the certificate.

Neelix · Post by **Neelix** » Wed Nov 17, 2021 7:51 am

Sounds to me like the installer is ignorant about :

a: The requirement to gland the knockouts - that really needs improvement

b: The IP ratings of holes in the top, sides and bottom of fuseboards - ditto

Someone-Else · Post by **Someone-Else** » Wed Nov 17, 2021 9:01 am

You can't afford to put the installation right, she can't afford to put the installation right, it doesn't need a certificate for just changing a switch.
You know the installation is wrong, If you leave any paperwork write on it that the installation it does not come up to standard and why, leave a price to correct it, you can't do everything for free.

kellys_eye · Post by **kellys_eye** » Wed Nov 17, 2021 9:13 am

If she asks - or you feel it's your responsibility - issue a notice for attention/rectification to 'cover yourself'. It's then up to the owner to rectify or not and as much as you feel a social responsibility you've done as much as you can and/or are required to do.

Someone-Else · Post by **Someone-Else** » Wed Nov 17, 2021 9:17 am

LadySpark, turn it on its head, it may be a 2nd hand CU, because she could not afford to pay for a new one.

Chippo1 · Post by **Chippo1** » Wed Nov 17, 2021 10:22 am

Maybe the holes are for ventilation !

Joking

LadySpark · Post by **LadySpark** » Thu Nov 18, 2021 1:41 am

Thank you for your replies.

Has anybody else ever seen this before? I don't think I have ever used a knock out hole on a consumer unit. I'm not even sure what they are there for!

I just don't understand why somebody would do that so I'm a bit reluctant to wade in in case they had a good reason that is beyond my expertise. (As an aside, this caution comes from working with Poles who used to "fix" perfectly good ring circuits into lines because that is how it is done in Poland.) What is the reason that there are knockout holes on the sides of consumer units? Has anyone actually used one ever?

I am a soft touch. I couldn't live with myself if a little old lady or her grandchild died because I left something really dangerous in easy reach. I'll look for a second hand consumer unit casing. The MCBs and RCDs are ok. I'll charge her a tiny amount for the work and do something.

kellys_eye · Post by **kellys_eye** » Thu Nov 18, 2021 8:45 am

If the CU was mounted on a solid (brick, concrete) surface you'd have no choice but to take cables in through the gland holes. Whilst I know many CU's are mounted on wood boards (standoffs) this is not 100% of the time. Indeed all the CU's I have in my workshops (albeit only 3 to 7 way jobbies) all have cables entering through glands.

Chippo1 · Post by **Chippo1** » Thu Nov 18, 2021 8:58 am

Er erm , knockouts are for taking cables via glands into the CCU , I.e maybe an incoming which is a PVC/SWA/PVC or ones going out from the CCU , like to shed or other location were a small local CCU is fitted !

All the cables on my main CCU enter and exit via the Knockouts , as I bushed and socketed the CCU onto Steel trunking ! Sparks who certificated installation did say wow , and that he would never normally do that due to time and expense unless it was specified and the cost allowed for !

kellys_eye · Post by **kellys_eye** » Thu Nov 18, 2021 10:22 am

Chippo1 wrote: ↑Thu Nov 18, 2021 8:58 am that he would never normally do that due to time and expense unless it was specified and the cost allowed for

Ka'ching!

We have a winner!

Neelix · Post by **Neelix** » Thu Nov 18, 2021 10:40 am

kellys_eye wrote: ↑Thu Nov 18, 2021 10:22 am
Chippo1 wrote: ↑Thu Nov 18, 2021 8:58 am that he would never normally do that due to time and expense unless it was specified and the cost allowed for
Ka'ching!

We have a winner!

The attitude about the glands is atrocious

Chippo1 · Post by **Chippo1** » Thu Nov 18, 2021 7:26 pm

Have I missed some thing here , what did I say that was so atrocious ?

LadySpark · Post by **LadySpark** » Fri Nov 19, 2021 3:38 am

OK I live in a town built as a London overspill in the 1970s and the government ran out of bricks so houses are generally timber frames with minimal brickwork and the cheapest construction possible. The entire town except a few old farmhouses is built of plasterboard and cladding lol. Therefore I always work with consumer units on plasterboard walls and it's pretty easy to get cables in from the back. It seems that it is my limited experience that is the problem here.

Am I right in saying:

- wires entering the consumer unit for each line and circuit via knock outs = perfectly normal practice in brick-built houses

- knockouts without glands = very dangerous

If so, just putting a gland on each incoming wire would be an acceptable solution?

I've only been doing this a couple of years. I only work locally. I remember when training coming across all sorts of things that I don't see in houses around here (clip-direct for example as it's easy enough to cut plasterboard walls with a multi-tool and tuck cables away out of sight). Am I overreacting to the use of the knock outs to run the cables in? I just need to add glands?

Chippo1 · Post by **Chippo1** » Fri Nov 19, 2021 9:07 am

In some ways not for me to say I do not have formal electrical qualifications ! But I have lots of experience with commercial installation associated with lifts ! Lift Reg ps over ride 18th and we did not have to comply , but most of our work was for high spec local authority installations a s via consultants. All lighting and power was run in singles in galv conduit and trunking. We always used metal CCus for years and never T & E

I was of the opinion that cables entering and leaving metal CCU,s under the 17th amendments and 18th need to be protected to prevent transmission of fire from the CCU into the property , so yes the cables running through knockouts need to be protected to prevent mechanical damage to the insulation but also for fire . So yes price to gland the cables and add steel blanks and back nuts to unused knockouts.

I go over the top with my own stuff as I tend to always do what I have always done steel trunking ect , mine runs from the CCU and across the loft of the bungalow , t&e s existing the trunking via glands , and 3 armoured entering/exiting via the appropriate glands , I have the time and the cost is insignificant doing it one self.

ericmark · Post by **ericmark** » Fri Nov 19, 2021 1:34 pm

I was trained as an industrial electrician but before Part P did work on homes, and we called electricians who worked on housing house bashers as in the main the work was rough, I was taught one terminal is for one wire, would not get very far with domestic with that idea, do try to limit to 3 wires.

But when Part P came in there was a move to better quality, grommets on knock outs, and earth sleeving. With grommets on industrial the distribution board would fill with dust, so all cables had stuffing glands, or SWA glands, only the Germans did without glands, and on a few jobs needed to pick up German electricians for not following the rules, free air instead of conduit bends for example.

It is easy to quote IP ratings, but in the real world need some common sense, or at least a tube of silicon sealant. The whole of domestic seems to be near enough engineering, so yes in theory need a tool to access, so getting some grommets cutting them and sliding over cables and into hole does not comply as can be removed without a tool, so just use a little silicon sealant to glue them in, once set can't be removed with tool. The grommet means cables can't chaff, and are not touching metal. Silicon blocks the hole.

Some people do go OTT, some one was complaining no grommet in back box, but plaster was holding cable firm, no way could it chaff. Could use expanding foam. But not enough to cause over heating.

I felt sorry for the electricians sent by social services to work on her house, I just crossed my fingers nothing went wrong until she when into hospital and I got it rewired. Did not DIY as speed was needed.