Am3 board rear snap out panels fire containment

[martinxxxxxx]

 Hi all I recently had my AC assessment this year I want your items that any more only item came up was the fact that I'd sent that the square panel back of the fuse board and visible through the fuse board was a 4" x 2" piece of the blackboard made of wood.

The assessor was not happy to see this What are your thoughts

 

[phil d]

I,ve discussed this with several manufacturers and they dont seem to think there is a problem,apparently fire will only escape through the front of the board,or at least that's what they seem to think! I had a heated debate with one of the reps from one of the larger manufacturers,he was showing me this new CU and all the glands and sealing options that they made for cables emerging through knockouts,when I asked about the big hole in the back,and stated that most cables enter through the back he was lost and just went back to wanting to discuss the glands and seal he'd previously mentioned.

 

[SBS Dave]

Hi Martin,

The most important part of the enclosure from a fire-containment point of view, is the horizontal top of the enclosure.

That is why it should be at least IP4X, ie it won't allow a 1mm wire through. Elsewhere, it can be IP2X, which equates to a 12.5mm probe.

The problem with IP4X on the top, is when the cable PVC melts and the IP4X becomes IP2X or worse.

The best solution is to have NO knockouts on the horizontal top and bring all cables through a back knockout, which needs only be IP2X.

This should be fairly easily achieved with all the cables coming through, but if there is any doubt, sealing the back knockout with a suitable sealant improves the IP2X rating, prevents combustion air entering and limits heat or flame propagation through the back.

That's why standoff pattresses or my Standoff frame are good ideas.

SBS Dave

 

[Rob_the_rich]

The requirements for IP4X on accessible top surfaces and IP2X elsewhere in enclosures (416.2) seem unchanged in AMD3 from AMD1. I can find no other mention in bs7671. I assume originally the top surface hole size restriction was to limit ingress of dirt etc falling into the enclosure. But if the top surface were inaccessible, bs7671 AMD3 allows IP2X,

the beama tech sheet http://www.beama.org.uk/resourceLibrary/technical-update-enhanced-fire-safety-for-consumer-units.html gives max 1mm holes for top surface, irrespective of whether accessible or not, and max 2.5mm for all other "accessible" surfaces. Holes in the back would be assumed to be inaccessible and subject to IP2X (12.5mm) as Dave says.

 

[Rob_the_rich]

as a further thought, perhaps the inspector was thinking of 422.4 if the building was made mainly of wood

I am thinking of 422.4.201 and 422.4.202 but not sure about whether an AMD3 CU would comply with the "relevant standard". With the back knockout gone, the inspector might have wanted to see a sheet of non-flammable material behind. dunno.

 

[Andy™]

the reg only states it must be made of non-exploding material. it makes no reference to sealing any holes, other than the usualy IP2/4x for front & sides etc. so your assessor can be as unhappy as he wants, but its compliant with a hole in the back...

 

[Sharpend]

Just to hijack slightly!

Am I right in thinking that switchgear is included in this amendment? Currently questioning an Electrical Designer, he wants to put a plastic TPN isolator at the front end of an install, I'm thinking that it should be metal (non combustible) now?

any thoughts confirmations or otherwise  

 

[Rob_the_rich]

Just to hijack slightly!

Am I right in thinking that switchgear is included in this amendment? Currently questioning an Electrical Designer, he wants to put a plastic TPN isolator at the front end of an install, I'm thinking that it should be metal (non combustible) now?

any thoughts confirmations or otherwise  

last I heard the IET agree with you, and the niceic agree with your designer.

 

[kerching]

Well, I was told that if it is a private isolator then 7671 applies and it needs enclosing in titanium...if it is owned by DNO then it can be made of cardboard 

this came straight from the mouth of the man  who 'knows his way around  a pie or two'.   LFB.  tony cable

 

[Sharpend]

last I heard the IET agree with you, and the niceic agree with your designer.

Thanks rob, clear as mud!

Well, I was told that if it is a private isolator then 7671 applies and it needs enclosing in titanium...if it is owned by DNO then it can be made of cardboard 

this came straight from the mouth of the man  who 'knows his way around  a pie or two'.   LFB.  tony cable

Don't expect anything less!  Pies that is  the rest is just pension talk. 

 

[steptoe]

well,

I have my assessment tomorrow,

domestic re-wire,

plastic enclosed isolator front end,

plastic enclosed 100mA TD with 63A MCB,

plastic CU understairs,

designed in 2008,

almost finished in 2016,

wonder how it will go,  :C

 

[Evans Electric]

As far as I can see ,   Amd 3  , reg  421-1-201  asks for consumer units  & similar switchgear assemblies to be made of fire resisting material  .   Then shows a preference for steel .

So , is a domestic isolator switch similar to a consumer unit  we ask ourselves ?  

After 500 years in the trade I look at the two , side by side , and I think ,   this 100A  DP isolator is nothing like a consumer unit whatsoever .   Its enclosure may as well be plastic , the same as the DNO cut-out .   ( Which used to be steel BTW  :C ) 

Again typical of this country today ,  jump in with stop gap solutions without applying logic .  

Picture the scene ... a man arrives at 221B Baker Street with a consumer unit under his arm.

Holmes :   " I see from your strange attire that  you have travelled back from the future, how can the good Doctor and I be of assistance?"

Man :       " My dear Holmes , we have been fitting these units for 60 years and suddenly they are going up in flames . 

                 What are we to do ?  Should we start building them from steel to contain the fire?"

Holmes:    " These boxes of plastic you speak of have been fine for 60 yrs ... so the cause is not with material my good man "

Man :       " Then what can it be , some deadly plot by Moriarty , some great ghostly hound chewing the cables ?"  

Holmes :    "  It is a one pipe problem , logic dictates there are two possible causes ,  (1) The devices inside the mysterious boxes 

                     are not as they used to be  or (2)   The artisans who fit them are incapable of tightening up a screw .

                      To consider the problem to be caused by the case itself is a total nonsense Sir . "

Watson :      " Again you amaze me Holmes !!"

Holmes:       "  Elementary my dear Watson .   Now Sir , take yourself back from whence you came ...and by the way ...your magic box

                       will never replace gaslight "!

 

[leesparkykent]

Just to hijack slightly!

Am I right in thinking that switchgear is included in this amendment? Currently questioning an Electrical Designer, he wants to put a plastic TPN isolator at the front end of an install, I'm thinking that it should be metal (non combustible) now?

any thoughts confirmations or otherwise  

only in a dwelling.

 

[Sharpend]

As far as I can see ,   Amd 3  , reg  421-1-201  asks for consumer units  & similar switchgear assemblies to be made of fire resisting material  .   Then shows a preference for steel .

So , is a domestic isolator switch similar to a consumer unit  we ask ourselves ?  

After 500 years in the trade I look at the two , side by side , and I think ,   this 100A  DP isolator is nothing like a consumer unit whatsoever .   Its enclosure may as well be plastic , the same as the DNO cut-out .   ( Which used to be steel BTW  :C ) 

Again typical of this country today ,  jump in with stop gap solutions without applying logic .  

Picture the scene ... a man arrives at 221B Baker Street with a consumer unit under his arm.

Holmes :   " I see from your strange attire that  you have travelled back from the future, how can the good Doctor and I be of assistance?"

Man :       " My dear Holmes , we have been fitting these units for 60 years and suddenly they are going up in flames . 

                 What are we to do ?  Should we start building them from steel to contain the fire?"

Holmes:    " These boxes of plastic you speak of have been fine for 60 yrs ... so the cause is not with material my good man "

Man :       " Then what can it be , some deadly plot by Moriarty , some great ghostly hound chewing the cables ?"  

Holmes :    "  It is a one pipe problem , logic dictates there are two possible causes ,  (1) The devices inside the mysterious boxes 

                     are not as they used to be  or (2)   The artisans who fit them are incapable of tightening up a screw .

                      To consider the problem to be caused by the case itself is a total nonsense Sir . "

Watson :      " Again you amaze me Holmes !!"

Holmes:       "  Elementary my dear Watson .   Now Sir , take yourself back from whence you came ...and by the way ...your magic box

                       will never replace gaslight "!

I've scoobed you not for quoting the Reg, but for the award winning script writing :Applaud  bravo, bravo

 

[leesparkykent]

only in a dwelling/domestic household premises.

 

[Sharpend]

only in a dwelling.

So does that not include an intake cupboard? 

Did you get those pics? Having a mare with the electrical designer (engineer)!!

 

[leesparkykent]

So does that not include an intake cupboard? 

Did you get those pics? Having a mare with the electrical designer (engineer)!!

Imo I wouldn't say it does. I'm at the job in the morning so will make sure to take some pics and post them on that other thread

 

[Rob_the_rich]

Thanks rob, clear as mud!

Sorry mate, I phoned both niceic and iet techs as I mentioned here



and and a few posts before. Mud is the word.

 

[Sharpend]

Imo I wouldn't say it does. I'm at the job in the morning so will make sure to take some pics and post them on that other thread

Cheers bud, I'll keep me 👁 out for them

 

[Evans Electric]

 Hi all I recently had my AC assessment this year I want your items that any more only item came up was the fact that I'd sent that the square panel back of the fuse board and visible through the fuse board was a 4" x 2" piece of the blackboard made of wood.

The assessor was not happy to see this What are your thoughts

Sherlock Holmes here ( From the past )     :    This means that the assessor still thinks the consumer is likely to burst into flames even

                                                                        though its made from steel .  Thus proving that the problem lies with the devices fitted

                                                                        or the fitter himself . 

Now I have large hound to deal with on Dartmoor ....Watson !!!   The games afoot ...bring your service revolver !!