So what about the old wooden back frame CU? Yes/No/Don't Know?

[SPECIAL LOCATION]

I was good - I went to bed. I behaved. I got up. Went to work. Waited ever-so patiently and yet no answer. Apache not going to be back until sat and would like some answers!Pray

You have been very good Apache..

Go and have one of Welshy's Twix's and one of KME's beers!!!

I was waiting to see if any one could back up there reasons with any reg references??

it seems not? I shall dig some out for you.. but a bit busy a the moment.. but as a quick example..

Protection against thermal effects Chapter 42 is only 6 pages long... pg 64....69

so if wooden frame is a "combustion" problem..

I would expect to find the reg in this section, maybe ???

Regs 421.2, 421.3, 421.4, & 421.5

talks about temperature in NORMAL operation,

or arcs or sparks emitted by fixed equipment in NORMAL operation

or fixed equipment causing focused heat,

or electrical equipment in areas containing flammable liquid...

which none of these directly relate to the Wylex CU!!

section 422 goes on to talk about areas with a particular risk of fire...

which most likely doesn't apply!?

All of the cables are insulated and sheathed and several mm away from the wood constuction....

So if it is permissible to pass an insulated and sheathed cable though a hole in a wooden floor joist...

why can they not pass into a CU with some wood structure which is further away??????

We all know common sense says it is wise to replace a very outdated design of CU...

BUT as a means of providing 'Overload' protection does it still comply with 17th..

(additional RCD's may need to be considered to satisfy some shock protection aspects)

 

[binky]

All of the cables are insulated and sheathed and several mm away from the wood constuction....

So if it is permissible to pass an insulated and sheathed cable though a hole in a wooden floor joist...

why can they not pass into a CU with some wood structure which is further away??????

If you've ever seen a fire in a CU, you would know what bunk that is SL

Also cable in CU is not sheathed, and wooden frame is much lighter wood construction than load bearing timbers - ergo much easier to set fire to.

 

[SPECIAL LOCATION]

If you've ever seen a fire in a CU, you would know what bunk that is SL

YES.

Totally plastic ONE.

and a electric meter melting as well come to think of it!

.. erm plastic & metal construction!

caused by overheating of BAD cable terminations..

Melting plastic dripping off board!

Spose we better not have any plastic CU's either?

but NOT caused by wood getting hot from expected temperatures from normal everyday use of the CU!

CU's are NOT expected to generate arcs & sparks,

focused heat, high thermal temperatures,

or be in close proximity to flammable liquids. in normal use of the CU!

well the Ones I install don't anyway!

very rarely see a wooden back CU with charing evidence around the enclosure?

I think you will find that generally cable sheath is burning well before any contact with the wood?

reconsider cause & effect NOT just is wood combustible!

Also cable in CU is not sheathed' date=' and wooden frame is much lighter wood construction than load bearing timbers - ergo much easier to set fire to.[/quote']

I believe All cables should be sheathed until they are INSIDE the enclosure

and well past direct contact with the wooden bits?

So which is the reg you refer to then to say the wooden frame is NON compliant?? ?:|

 

[binky]

I think you will find that generally cable sheath is burning well before any contact with the wood?

reconsider cause & effect NOT just is wood combustible!

I believe All cables should be sheathed until they are INSIDE the enclosure

and well past direct contact with the wooden bits?

And burning sheath sets fire to wood - though never actually seen burn't wood enclosure (maybe because there's no house left)

And once inside enclosure I strip back sheath sometimes to edge on enclosure, as in very close to wood or plastic.

Have often wondered why plastic CUs aren't fire retardent (maybe they are but have never seen any reference to it) so debatable whether they are any better than wood, other than when fitted with MCBs/RCDs hopefully fire would not propagate for so long ???????

Am going to study regs now once I've filled in PIR I've just done - trying to put finger on fault code for sockets too close to gas hob. Back soon

 

[binky]

Gert ya!!!

BS7671 a very innocuous ref in 526.5 suitable enclosures etc which refers you off to

BS 6458-2.1 Glow wire tests and

BS476 Pt5 ignitability characteristics part 'P' - which is refered to in the Inspection and Testing handbook for 'wooden mounted accessories' section 4 I think (left book downstairs and not walking down to get it again)

I would continue but I haven't got copies of these standards, and aint going to get them neither

 

[SPECIAL LOCATION]

Gert ya!!!BS7671 a very innocuous ref in 526.5 suitable enclosures etc which refers you off to

BS 6458-2.1 Glow wire tests and

BS476 Pt5 ignitability characteristics part 'P' - which is refered to in the Inspection and Testing handbook for 'wooden mounted accessories' section 4 I think (left book downstairs and not walking down to get it again)

I would continue but I haven't got copies of these standards, and aint going to get them neither

I am aware of these regs Binky.. and I know where you are coming from

BUT I just don't think they directly relate to the wylex CU??

In a nutshell we all know the CU is pasts its good working life..

offering limited protection...

But I don't think you could say to a customer the CU doesn't comply just because it has a wooden back frame...

{I always like to have a note of any regs to back up my observations/recommendations in case a customer comes back questioning stuff!}

And if they wanted to they could argue that the genuine risk of combustion is negligible!!

526.5 (pg 106 the big red book, if any one else want to look)

refers to THREE options of enclosure where and electrical termination can be made..

and it states you can utilise ONE or a combination of the three options.

i) is a suitable accessory complying with the appropriate product standard

ii) is an equipment enclosure complying with the appropriate product standard.

iii) is an enclosure formed by building materials ... (this is the one that has to meet the BS 476-4 non-commutable test.)

Amongst other things, "Equipment enclosures" includes distribution boards, (definitions, Equipment [pg24] -> electrical equipment [pg23])

IMHO

I am reasonably confident that the wylex CU's were built to an agreed appropriate standard,

i.e. not cobbled together by a DIY bob in his garage.

thus option 'ii) of 526.5' it is an enclosure complying with an appropriate product standard for that enclosure.

Wooden accessories...

Approved Doc P, Appendix C, older practice, Page 38

These are Switches, Sockets, Light fittings, (as it says in first sentence)....

as opposed to Distribution boards.. an assembly containing switching, protection etc.. (Part 2 Def Big Red book pg 22)

Even the accessories last sentence only says "MAY not comply".. rather than do not comply???

Lamp holders, sockets, etc.. have a greater risk of getting warm/hot during normal use...

wires bunched in tighter... closer proximity to back box... less air circulation...

Whereas under NORMAL use a CU doesn't,t get hot or even marginally warm!

The main places I have seen overheating of wiring etc.. is in places such as..

Lamp holders, especially batten holders direct onto ceiling, bulkhead lights.

Socket outlets, Shower isolator switches, Immersion heater switches.. (accessories) etc..

probably account for 99% of cables with signs of melting or blackened connectors.

CU wiring is the minority.

IHMO

the wooden back frame is a red herring in this part of a PIR..

there are far easier reasons to suggest replacement would be wise without even mentioning combustable wooden back frame...

Again.. in reality there are still LOADS of these wooden framed CU's out there..

and light switches with wooden mounting boxes..

But they are not bursting into flames every week!

I have done searches on the NICEIC tech manual for info re wooden back-box etc..

NOUGHT!!

if it was a clear cut NO-NO... I reckon they would have some section on it!!!

Still tis blo0dy good getting the ole grey cells ticking thinking these bit over!!

I went to another job today to quote for a garden supply to greenhouse...

ARGGGH 8-way wylex.. WOODEN frame... some RUBBER sheathed cables... NO bonding

In fact it looked like the tails were only 10mm!!! or its the thinest 16mm I have seen! ouch!

I'm going to quote to run direct back to incoming meter.. stick new little 2-way RCD box. and do bonding!

and advise them the rest of the installation is probably due for a full inspection or most probably a rewire! :|

Blimey! thats another long post... my thumbs hurting now!!! :^O :z:z:z

Guiness Drink

 

[binky]

Like most things regs change, and no doubt 'woodies' (my nickname for wood backed CU) complied to the appropiate standards of their time, in the same way Morris Minors were considered really good cars in their time. But we inspect to 17th regs, and no doubt if we read the appropiate BS docs, a wooden enclosure fails and therefore should be noted as such on PIR, but probable only justifies code 4 defect, because it is not an immediate danger to public.

The biggest problem with regs is they are written in legal jargon - hence MAY NOT comply - you could no doubt design a wood enclosure that does comply with a bit of thought and intuition. Thay also tend to refer to other specs to detail design of cmponents to avoid re-writing regs book too often, hence regs are not very useful when trying to research these issues. I have also made frequent comments to NIC to issues more definitive guidelines on older equipment instead of just banging on about the up to date stuff which is easily researched by any one with half a brain.

Anyway going back to woodies, my local BC inspector says they are 'condemmable' - who am I to argue????? I also find if i use the Morris Minor analogy, nobody (yet) argues that a more modern unit would not be far wiser

 

[SPECIAL LOCATION]

Ok..

just to try and conclude this thread now.....

Or start it going again? ; \ ?:| :^O :^O

Here are a few of my thoughts on these old Wylex Jobbies.. wood OR plastic!!!

General observations would be somewhere along the lines of the following points.. again some may be debatable!!

I have tried to give some reasoning for each point...

Exposed live parts when cover removed:

There is a risk of electric shock during alteration / maintenance work..

especially if undertaken by non skilled person.

416.1 basic insulation of live parts.. Live parts completely covered with insulation which can only be removed by destruction.

416.2.1 live parts inside enclosures or behind barriers.

416.2.3. barrier firmly secured in place & have sufficient stability & durability to maintain required protection & separation from live parts in the known conditions o normal service, taking account of external influence.

Risk of incorrect fuse wire rating fitted in fuse. when 3036

 

[binky]

By eck there's some typing going on here

Totally agree with all the above points SL, and if I remember rightly the exposed live busbars with cover off is Failure Code 1 anyway (going to have to try and find where I read that again now)

One point though, lots of modern CUs I've seen have big holes in top aswell . Personally I try to avoid the top for cable entry and have even gone as far as siliconing holes, and maybe I sholud start another thread on this matter? :|

 

[SPECIAL LOCATION]

By eck there's some typing going on here

I've had to stick me fingers in a bucket of KME's beer to cool them off!!!Guiness Drink

Totally agree with all the above points SL' date=' and if I remember rightly the exposed live busbars with cover off is Failure Code 1 anyway (going to have to try and find where I read that again now)

[/quote']

There is a get-out-clause in the regs about if the cover is removed by the use of a tool...

It is considered that only competent persons would open the cover up.... so can get round it, Still very dangerous IMO!.

Which is why all new-type boards either have enclosed bus-bars or a secondary barrier!

(bit like that bit about zones in bathrooms 701.32.3 last sentence, under a bath access by tool considered OUTSIDE of zones! so you could put connections for the old whirlpool stuff etc..)

One point though' date=' lots of modern CUs I've seen have big holes in top as well . Personally I try to avoid the top for cable entry and have even gone as far as siliconing holes, and maybe I sholud start another thread on this matter? :| [/quote']

If you will pardon the expression I always try and use the rear entries! (ohh:O morning vicar!Blushing) :^O

stick a couple of battens or spacers and you cut the knock-out at the back as much as you want! :|

 

[binky]

When I remember to pich some 2 by 1 from me kitchen fitter mate I do this too. Recently came across a CU with very entry knocked out and 1 cable fitted to each - wish I had photographed it as probably the worst CU change I had ever seen.