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Discuss Adding to an old mem board? in the Electrical Forum area at ElectriciansForums.net

happyhippydad

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Morning..

I need to get a shower supply from the 45a mem fuse in the picture below, this will first go to an RCD enclosure next to the board.

mem.jpg

I haven't added to a REALLY old mem board before (fuses). I realise it may be a silly question but is it ok to add a circuit to this board? With the more common wylex fuse box it's fine but this board does seem really old. The customer has said he doesn't want to change the board.

Also, does this board contain asbestos rope behind the fuses?

Thanks.
 
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telectrix

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fine to feed a separate RCD in enclosure from the 45A fuse. don't worry about asbestos. as long as it ain't disturbed, you'll be able to father children for years to come.
 

littlespark

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Don’t you just hate it when someone puts a fuse in upside down?

I’d try to convince customer into a board change. False economy adding an rcd enclosure now, then a new board in the future.
Tell them it’s a serious fire risk or something.... can no longer get spares etc.

Think of the grief you’ll get when, after you’re finished the shiny new shower circuit with rcd protection, their sockets or lights develops a fault.... first thing they will tell anyone is: “there was an electrician in last week, and it was all fine before that”
 

Leesparkykent

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Don’t forget your 0.725 factor. And if your adding an RCD in an enclosure why not just add a two way board just for the shower instead?
 

Gavin John Hyde

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Agree with @Leesparkykent i would go down the new small board just for shower route. On the positive side get one with an extra spare way for future works.
Saves messing with the current board. Wont be looking at too much cost wise either.
 
T

Toneyz

Tell them it’s a serious fire risk or something.... can no longer get spares etc.
Sorry, I think this is morally wrong, I am sure that Happyhippydad has done an assessment on the existing supply, existing consumer unit and bonding (inc supplementary) One question would be that if by adding an electric shower all the other circuits need to be RCD protected then a professional argument can be made on compliance and fact.
 

happyhippydad

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  • #8
Is there not a cooker circuit then?
No, it's actually feeding a 9.5kW shower at present, although it still states 'cooker' on the fuse. The present cable is 6mm and runs through conduit and insulation throughout most of the run so it's not acceptable. I'm going to be upgrading to 10mm and moving the isolation switch. At present the isolation switch for the upstairs shower is the old cooker switch in the downstairs kitchen and the elderly couple have lots of walking to do just for a shower!
 

happyhippydad

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Don’t forget your 0.725 factor. And if your adding an RCD in an enclosure why not just add a two way board just for the shower instead?
Are you suggesting splitting the tails in a Henly block to feed the separate shower unit? That would probably end up being more work and a higher quote as I would also have to fit a separate isolation switch to isolate both the fuse box and the shower unit so that it meets reg 462.1.201 (BBB) [reg 537.1.4 - BGB-just for Tel ;)]

It would definitely be a better job I agree, but coming straight from the 45A mem fuse would still be acceptable? CCC of 10mm 64A x 0.725 = 46.4A (just above the 45A fuse!)
 

happyhippydad

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Sorry, I think this is morally wrong, I am sure that Happyhippydad has done an assessment on the existing supply, existing consumer unit and bonding (inc supplementary) One question would be that if by adding an electric shower all the other circuits need to be RCD protected then a professional argument can be made on compliance and fact.
Quite agree Anthony although I'm sure Littlespark was saying it a little tongue in cheek. I will however be pushing for a new CU, but I shall be honest in my facts! :)
Main bonding has all recently been done. 10mm to gas and water.
 

happyhippydad

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Ps.. do they have asbestos?
 

freddo

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As much as I like these fuseboards the IP rating isn't very good for household use, fingers can easily touch exposed parts. The wax missing from the 30A fuse isn't great either. Now would be a great time for an upgrade, tell the customer to stop being a stingy old c***. After all safety would be improved quite a bit with a properly installed modern consumer unit.
Ps.. do they have asbestos?
Yes as it appears these are rewirable fuses. However removinng a fuse carrier isn't going to cause a Chernobyl.

As mentioned above, for a client I would install the new circuit in a separate small consumer unit if they won't replace the existing one (which really is a false economy). Can't get blamed for any problems further down the line then.
 

Leesparkykent

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Are you suggesting splitting the tails in a Henly block to feed the separate shower unit? That would probably end up being more work and a higher quote as I would also have to fit a separate isolation switch to isolate both the fuse box and the shower unit so that it meets reg 462.1.201 (BBB) [reg 537.1.4 - BGB-just for Tel ;)]

It would definitely be a better job I agree, but coming straight from the 45A mem fuse would still be acceptable? CCC of 10mm 64A x 0.725 = 46.4A (just above the 45A fuse!)
I wouldn’t fit an isolator on the tails if both boards are next to each other.

Technical Guide: Henley blocks and isolation - https://www.voltimum.co.uk/articles/technical-guide-henley-blocks-and


And if you didn’t fit the isolator then realistically how much is it going to add to the quote by adding the 2nd board rather than an RCD in an enclosure....£20?
 
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Risteard

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I wouldn’t fit an isolator on the tails if both boards are next to each other.

Technical Guide: Henley blocks and isolation - https://www.voltimum.co.uk/articles/technical-guide-henley-blocks-and


And if you didn’t fit the isolator then realistically how much is it going to add to the quote by adding the 2nd board rather than an RCD in an enclosure....£20?
Neither would I generally speaking. They can be said to be two installations from a Regs point-of-view (even stated in IET publications), strange as it may seem.
 

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