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Topic Title: MF junction boxs
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Created On: 28 September 2012 06:21 PM
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 28 September 2012 06:21 PM
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CMD

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Hi

Ive just been infromed that Wago have now got the MF approval for ther junction boxs , I havent seen them yet but believe they have had to alter the lid design on them with a locking assembly.

Regards
 28 September 2012 06:50 PM
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weirdbeard

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Originally posted by: CMD


Ive just been infromed that Wago have now got the MF approval for ther junction boxs , I havent seen them yet but believe they have had to alter the lid design on them with a locking assembly.



Great! So something that is designed to be inaccessible is ok now it has a locking facility?
 28 September 2012 07:37 PM
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alanblaby

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I was speaking to the inventor last week at Elex, he said they are exactly the same, just now will have the MF mark.
 28 September 2012 08:16 PM
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TeesdaleSpark

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Things aren't quite that simple though:

www.wagobox.com/docs/files/Wagobox-mf-qna-v3.pdf
 29 September 2012 07:48 AM
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Rulland

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Originally posted by: weirdbeard

Originally posted by: CMD





Ive just been infromed that Wago have now got the MF approval for ther junction boxs , I havent seen them yet but believe they have had to alter the lid design on them with a locking assembly.







Great! So something that is designed to be inaccessible is ok now it has a locking facility?


Lol

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 29 September 2012 10:49 AM
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alancapon

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Originally posted by: TeesdaleSpark
Things aren't quite that simple though:
www.wagobox.com/docs/files/Wagobox-mf-qna-v3.pdf

An interesting document. It looks as though using a "maintenance free wagobox" to extend a ring, you would have to either use the larger 6mm² "773" connectors, or de-rate the ring's opd to 20A. You would also need to use a seperate wagobox for each leg of the ring.

Regards,

Alan.
 29 September 2012 11:31 AM
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maltrefor

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Originally posted by: alancapon

Originally posted by: TeesdaleSpark

Things aren't quite that simple though:

www.wagobox.com/docs/files/Wagobox-mf-qna-v3.pdf


An interesting document. It looks as though using a "maintenance free wagobox" to extend a ring, you would have to either use the larger 6mm² "773" connectors, or de-rate the ring's opd to 20A. You would also need to use a seperate wagobox for each leg of the ring.


Regards,



Alan.


Why would you need to de-rate the OPD as 2.5 mm2 6242YH is only rated
at 20A anyway ???
 29 September 2012 12:15 PM
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alancapon

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Originally posted by: maltrefor
Why would you need to de-rate the OPD as 2.5 mm2 6242YH is only rated at 20A anyway ???

Try Table 2 of Wago's document (link provided by TeesdaleSpark). You will find that only the 6mm² "773" connectors are listed as being suitable for use with a 32A opd in "maintenance free" applications.

Regards,

Alan.
 29 September 2012 12:38 PM
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sparkingchip

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I'm going to have to read that a few times to get my head around it.

If then you tee into a ring to install a connect a spur the the aggregate current will be 40 amps, so the following still applies:

"Can I use a Wagobox to extend a ring main in an inaccessible location?
Yes, In a maintenance free situation the maximum Iag limitation will require two separate Wagoboxes to be used
as the maximum potential Iag is 72A when using a single Wagobox and this exceeds the BS5733-MF limitation on
the box.
When using two Wagobox enclosures either the 773 or 222 terminals can be used as the maximum Iag in each
Wagobox will not exceed 40A."

Andy
 29 September 2012 12:44 PM
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alancapon

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It would be interesting to know what the issue is. From what is / isn't written in the document, the only thing I can think about is overheating of the individual terminals, perhaps due to the method the cores are restrained / the current path through the terminal.

More questions than answers . . .

Regards,

Alan.
 29 September 2012 01:00 PM
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sparkingchip

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If for arguments sake you ran a lighting circuit into a box live in 10 amps, switch feed 10 amps, switch live 10 amps, then had a eight way connector supplying lights with further junction boxes and a then eight way neutral connector, will the aggregate be 40 amps or could we be looking at an aggregate of 60 amps, exceeding the maximum of 50 amps for the box just with a 10 amp lighting circuit?

Andy

https://docs.google.com/viewer?url=http://www.wagobox.com/docs/files/WA_Row_of_Downlights.pdf&pli=1

Edited: 29 September 2012 at 09:59 PM by sparkingchip
 29 September 2012 01:17 PM
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weirdbeard

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Originally posted by: alancapon



An interesting document. It looks as though using a "maintenance free wagobox" to extend a ring, you would have to either use the larger 6mm² "773" connectors, or de-rate the ring's opd to 20A. You would also need to use a seperate wagobox for each leg of the ring.
.


Agreed it is interesting, and also seems a bit bizarre and convoluted, this concept of agregate current based on the opd size within an enclosure has me a bit confused...

To extend a ring you need to use 2 enclosures, seems fair enough, the same as you would do if using normal accessible JB's, but what about cutting into a ring to take a spur off - If i'm reading things right wouldn't the aggregate current according to their diagrams be 96A, so not permitted?

Either way on the very rare occasion that I would make an innaccessible joint (can't say I've ever come across an inaccessible joint that I couldn't find, just some that are harder to access than others) I don't think I will be using this method, unless wago want to send me a large box of freebies to help change my mind!
 29 September 2012 01:29 PM
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sparkingchip

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Now bear in mind that at the Elex show the boxes and connectors are on different stands, because Wago and Wago Box are not the same company, then consider you are using an configurable box.

So you are taking products from two companies and designing the box yourself, in in so doing you are expected to derate all the components if it is not going to be accessible at a future time.

However if the box is located under a trap in a wooden floor with the trap screwed down, with carpet and underlay over the trap, then presumably you don't have to derate the components.

So if the above is correct then there appears to be a be major exercise in covering ones rear end.

Andy
 29 September 2012 01:44 PM
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OMS

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The aggregate current is just a simplistic way of expressing the limits on temperature rise.

As Wago can't identify how electricians will configure the terminal blocks inside the Wagobox, they've attempted to give working limits on total current which translates to the heating effect and thus the limit on rise of terminal temperature - simples.

Regards

OMS

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 29 September 2012 02:35 PM
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weirdbeard

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Originally posted by: OMS

The aggregate current is just a simplistic way of expressing the limits on temperature rise.



As Wago can't identify how electricians will configure the terminal blocks inside the Wagobox, they've attempted to give working limits on total current which translates to the heating effect and thus the limit on rise of terminal temperature - simples.



Hi OMS, unusual to hear from you at weekends!?
It doesn't seem simples to me! According to the manufacturers instructions if I have a 10A opd and say want to split a 1.5mm cable to supply 7 of 5W led down lights, the load would be about 35W, yet the aggregate current going by the instructions would be 80A? seems a bit daft!
 29 September 2012 02:42 PM
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daveparry1

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But on a 32 amp ring each leg will only be carrying 16 amps Weirdbeard! (ignoring any out-of-balance issues of course)

Dave.
 29 September 2012 02:48 PM
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OMS

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You know how it is - keeping the wheels of industry grinding away generating work for the electrical trade - churning out a few designs for a client who actually has some money to spend (although not much on fees - )

It depends on if you want to take each of the luminaires in and out of the wago box

Don't you actually have the scenario in Fig 2 (without the loop to the next group of fittings) - so you have a max aggregate of 2 x 10A CPD rating = 20A. That's assuming you have one JB dealing with all five luminaires.

If you want to use it as an RB4 style joint box with all five luminaires and switches wired back to it then you have the 10A in, the you have whatever proportion of that each fitting takes in and the number of switches in direct proportion to the number of lamps switched in, plus a load going out if present

So, lets say it's a 10A circuit and each light is 2A and each light has it's own switch - so you have 10A in plus 5 x 2A for the lamps via the switchwires = 20A - same as Fig 1

Or that's how I would see it anyway - so you could use 733's with no trouble (I guess bourne out by the thousands already installed that haven't burst into flames - yet)

Regards

OMS

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 29 September 2012 03:00 PM
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weirdbeard

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Originally posted by: OMS

(I guess bourne out by the thousands already installed that haven't burst into flames - yet)



And to add to that there must be millions of 'inaccesible' non mf standard ashley JX01 junctions under floor boards in perfect working order that need replacing, though if they are inaccessible how can they be replaced!
 29 September 2012 03:19 PM
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OMS

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Yup - life goes on, no one dies - it's only the positively anal get hung up about these things - unless of course it becomes a matter of contract then everyone has something to say

regards

OMS

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 29 September 2012 09:01 PM
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sparkingchip

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I thought it might make more sense if I read it again for another time after a break of several hours, however I'm not convinced by some of this apparently well presented document reading it again I picked up on this which may be a load of old tosh:

"For circuits using 4.0mm2 or 6.0mm2 twin and earth use the 773-173 with a 20A or 32A circuit protective device
as appropriate.
(Note that as the Wagobox can only accommodate two 773-173 terminals the Max Iag will not exceed 2x 32A for
6.0mm2 cable)"

Is it me or is that stupid

Andy
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