Discuss Sealing a consumer unit entry points?? in the Electrical Forum area at ElectriciansForums.net

leebut

Regular EF Member
Messages
101
Location
Bury
Hello Guys


I'm going to put my Tin hat on and close the curtains so the Regs police can't arrest me for asking this question again, I can only find old threads pre 18th edition so please advise me if I'm missing something


I've just been watching a guy on Youtube doing a board change who's said that to comply with the 18th edition of the Wiring Regulations you must seal ALL entry holes into a consumer unit regardless of them coming through the bottom, top, sides or rear entry with a suitable intumescent mastic to stop the spread of fire into the fabrication of the building!!!


I personally am NOT aware that anything changed in the 18th Edition to say all entry points have to be fire sealed I've been looking online tonight and can only find write ups from "Wiring Matters"

Stating


Sealing of wiring entries
It is important for the installer to seal all openings into the enclosure or cabinet for cables, conduits, trunking or ducting that remain after the installation of cables - see Figure 6. The intent of the sealing is to ensure that, as far as is reasonably practicable, any fire is contained within the enclosure or cabinet and the escape of flames to the surroundings of the cabinet or enclosure or into conduits trunking or ducting is minimised, as intended by Regulation 421.1.201.
Good workmanship and proper materials must be used, and account must be taken of the manufacturer’s relevant instructions, if any.


Regulation 421.1.201 Does not mention sealing any apertures in a consumer unit with, grommets, glands or sealant and does not mention that the Metal clad board cannot be fitted to a timber backboard. So why is the IET saying we are to be sealing the holes , personally I've been installing all my boards with cables entering from behind and mounting my boards on the existing wooden backboards using a length of stick on trunking as a framework around the consumer unit.


Am I wrong???
 

Midwest

Electrician's Arms
Messages
11,184
Location
Oxfordshire
When this reg first come out, the guidance was only ‘seal’ to the appropriate IP rating as previously mentioned. Then Wylex started flogging intumescent bags to go inside their CU’s, then the grown ups at the IET came out with that crap about contains a fire etc.

On my very last assessment two years ago, my Elecsa assessor suggested just to follow the IP rating, and don’t worry about mounting on wood.

I suspect the next thing, will be not to use plastic raw plugs to fix the CU to none flammable structure.
 
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leebut

Regular EF Member
Messages
101
Location
Bury
When this reg first come out, the guidance was only ‘seal’ to the appropriate IP rating as previously mentioned. Then Wylex started flogging intumescent bags to go inside their CU’s, then the grown ups at the IET came out with that crap about contains a fire etc.

On my very last assessment two years ago, my Elecsa assessor suggested just to follow the IP rating, and don’t worry about mounting on wood.

I suspect the next thing, will be not to use plastic raw plugs to fix the CU to none flammable structure.
The plastic rawlplug was brought up at my last assessment, there’s no concern over them as the wall they’re in will support the clips or consumer unit.

This idea of sealing up all the opening with intumescent sealant seems another cash generator to subsidise the cost of changing to metal consumer units
 

Spoon

Forum Mentor
Messages
7,166
Location
Lancashire
When this reg first come out, the guidance was only ‘seal’ to the appropriate IP rating as previously mentioned. Then Wylex started flogging intumescent bags to go inside their CU’s, then the grown ups at the IET came out with that crap about contains a fire etc.

On my very last assessment two years ago, my Elecsa assessor suggested just to follow the IP rating, and don’t worry about mounting on wood.

I suspect the next thing, will be not to use plastic raw plugs to fix the CU to none flammable structure.
If you will the CU up with water then they never catch fire..... Job done...
 
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leebut

Regular EF Member
Messages
101
Location
Bury
You put the water in a plastic bags, silly..... Then when there is a fire the bags burst and put out the fire....
You must work for the London Fire Brigade, what a fantastic idea because the water would then trip the rcd’s and would make the house dead!!
 

richy3333

Forum Mentor
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2,028
Location
North West Scotland
That guys a roaster. Shoves wago boxes in ceilings and reckons they are MF - not the way he does em, they aren’t.
He makes out he’s experienced but often says things that suggests he’s a newbie.
Ignore his ideas.
 
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leebut

Regular EF Member
Messages
101
Location
Bury
That guys a roaster. Shoves wago boxes in ceilings and reckons they are MF - not the way he does em, they aren’t.
He makes out he’s experienced but often says things that suggests he’s a newbie.
Ignore his ideas.
Who you talking about hope your not talking about me that’s certainly not my workmanship
 

Dustydazzler

Regular EF Member
Messages
1,018
Location
Surrey
Are we talking about CHris the handyman youtuber sparky plumber builder Tiler plasterer gezza man

 
Last edited:

Charlie_

Electrician's Arms
Messages
2,098
Location
Doncaster & Isle of Man
Cable access into the metal consumer unit must maintain the integrity of the non-combustable consumer unit so far as reasonably practicable. This can generally be achieved by the installer ensuring that cable access holes they make in the enclosure do not to leave gaps greater than: · 1.0 mm for the horizontal top surface and · 2.5 mm for all other surfaces of the enclosure that are accessible after installation. For rear cable access, the minimum number of knockout(s) shall be removed and a cable protector fitted; see illustration above. Tests on hager consumer units have indicated that there is no specific need for external fire rated cable glands or intumescent sealing in addition to the guidance below, with respect to achieving a non-combustible enclosure. However this does not preclude the designer/installer from using fire rated cable glands or external intumescent sealing should they consider necessary. Internal intumescent pads shall not be used.
 

buzzlightyear

please let me back in to the prison cell.
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star command
Cable access into the metal consumer unit must maintain the integrity of the non-combustable consumer unit so far as reasonably practicable. This can generally be achieved by the installer ensuring that cable access holes they make in the enclosure do not to leave gaps greater than: · 1.0 mm for the horizontal top surface and · 2.5 mm for all other surfaces of the enclosure that are accessible after installation. For rear cable access, the minimum number of knockout(s) shall be removed and a cable protector fitted; see illustration above. Tests on hager consumer units have indicated that there is no specific need for external fire rated cable glands or intumescent sealing in addition to the guidance below, with respect to achieving a non-combustible enclosure. However this does not preclude the designer/installer from using fire rated cable glands or external intumescent sealing should they consider necessary. Internal intumescent pads shall not be used.
well done Charlie I could not put it better me self .
 

Matthewd29

Regular EF Member
Messages
1,192
Location
Belfast
It really is out of control they will want us to make it fully air tight and pressure test it before were done
 
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leebut

Regular EF Member
Messages
101
Location
Bury
It really is out of control they will want us to make it fully air tight and pressure test it before were done
I was told initially sometime back that the consumer units need not be sealed because the main accelerant was the plastic CU so the steel CU was enough to stop a spread of fire, my question at the time was if the plastic CU were to be replaced with steel what about the MCB and plastic blanks why are they not being replaced with a fire proof alternative.

The answers I've been told is, the fires start from loose terminals in the tops of MCB's and the flames melt the plastic CU which spreads the fire, so any opening below the top of the CU doesn't need sealed, hence the reason why I bring my cables in through the back knock outs and I only put flexible grommet strip round to stop damage to the outer sheathing.

An alternative I was told about was to install a length of deep trunking along the top of the CU and run all cables into the trunking through the knockout in the top of the CU but I'm skeptical that that would work.

I personally don't like the look of loads of glands poking out the top of a CU I prefer them to come out the back.


OPINIONS OPINIONS OPINIONS!!!!
 
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Matthewd29

Regular EF Member
Messages
1,192
Location
Belfast
I was told initially sometime back that the consumer units need not be sealed because the main accelerant was the plastic CU so the steel CU was enough to stop a spread of fire, my question at the time was if the plastic CU were to be replaced with steel what about the MCB and plastic blanks why are they not being replaced with a fire proof alternative.

The answers I've been told is, the fires start from loose terminals in the tops of MCB's and the flames melt the plastic CU which spreads the fire, so any opening below the top of the CU doesn't need sealed, hence the reason why I bring my cables in through the back knock outs and I only put flexible grommet strip round to stop damage to the outer sheathing.

An alternative I was told about was to install a length of deep trunking along the top of the CU and run all cables into the trunking through the knockout in the top of the CU but I'm skeptical that that would work.

I personally don't like the look of loads of glands poking out the top of a CU I prefer them to come out the back.


OPINIONS OPINIONS OPINIONS!!!!
I would love to meet the people that make these rules. Admittedly I like the metal boards a lot more than the plastic ones as they had a real cheap feel to them but it's getting over the top. Have to be careful with the rest entry through wood because wood burns can't win going to have to carry a sheet of fire board with me now as well as all the other rubbish
 

ipf

Forum Mentor
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4,858
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Walmington-on-Sea/Lancashire
The answers I've been told is, the fires start from loose terminals in the tops of MCB's and the flames melt the plastic CU which spreads the fire, so any opening below the top of the CU doesn't need sealed, hence the reason why I bring my cables in through the back knock outs and I only put flexible grommet strip round to stop damage to the outer sheathing.
Agree. There's nothing wrong with a piece of ply stood off the wall for rear entry...
 
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leebut

Regular EF Member
Messages
101
Location
Bury
Agree. There's nothing wrong with a piece of ply stood off the wall for rear entry...
I mount my boards on a frame of sticky trunking using longer screws with washers so the plywood is further away from the CU so less chance of scorching or fire, the idea of the metal CU is to take away the accelerant so I don't understand the logic of sealing the knock out making any additional work harder to carry out
 

ipf

Forum Mentor
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4,858
Location
Walmington-on-Sea/Lancashire
I mount my boards on a frame of sticky trunking using longer screws with washers so the plywood is further away from the CU so less chance of scorching or fire, the idea of the metal CU is to take away the accelerant so I don't understand the logic of sealing the knock out making any additional work harder to carry out
To tell you the truth, I don't do many these days but I've access to various bits of ply and wood machines so it's just make up as required......don't even use grommet strip...make the wood slots smaller than the metal and smooth nicely...no problem. Good ply wood is no fire hazard.
 

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