Adding fused spurs for appliances to existing ring no 30ma RCD old fuse box ?

[Hayd]

I have been asked to add 2 fused spurs supplying under unit dishwaher and washing machine to an existing kitchen ring. The fuse board has 3036 wire fuses and has a large 100ma RCD protecting it. TN-c-s system, earthing and bonding are fine. Is it okay to add these spurs or do I somehow have to add rcd protection to that circuit alone ( the customer does not want a fuse board upgrade which would probably be the safer option.)? There is also no room where the fuse box is to add any further boxes or devices.

 

[Sintra]

Have you got a copy of BS 7671 or the on site guide.

 

[bigbaddave]

Have a think about this one.. What is another way of RCD protecting your work? that will not cost much more.

But secondly does the said work need RCD protecting ??

 

[Paul.M]

Surface mount the cables (clipped direct) in the under cupboards and no RCD is needed (long as Zs and disconnection times are met). If that is not possible you will have to use conduit or an RCD socket but that looks naff in a kitchen.

 

[wildgoose]

Must be rcd protected fused spurs to meet regs. Also the cable from the ring to the rcd spurs, needs to be mechanically protected or visibly surface clipped.
I've previously converted the existing socket into a dual box (single socket with the rcd spur. This overcomes the connection wire difficulty above.

Finally, it's work being done in a kitchen so it must be LABC notified and that means a test report - easy if you are registered as you probably know??

 

[Hayd]

Must be rcd protected fused spurs to meet regs. Also the cable from the ring to the rcd spurs, needs to be mechanically protected or visibly surface clipped.
I've previously converted the existing socket into a dual box (single socket with the rcd spur. This overcomes the connection wire difficulty above.

Finally, it's work being done in a kitchen so it must be LABC notified and that means a test report - easy if you are registered as you probably know??

All as I thought, but just good to run things past more experienced sparks. I think best plan seems to be an external 30ma rcd mounted just outside where the fuse box is, then wire the kitchen ring to that before it goes back to the CU, to protect the whole kitchen.

Feel free to offer any better ideas.

Thanks

 

[wildgoose]

Ok but your customer doesn't want to upgrade the old 3036 fuseboard?? By rcd protecting the kitchen ring, you are of course now taking responsibility for that complete circuit. I hope it has not been modified too much in the past to make things difficult and that their no N/E faults or insulation issues?

Before you commit to doing it this way, I advise you do a few basic measurements from the fuse box end. Then you can make the call on which solution you offer to the customer with associated cost's.

I'm assuming you are a Spark and this is your customer - right?

 

[Paul.M]

Must be rcd protected fused spurs to meet regs. Also the cable from the ring to the rcd spurs, needs to be mechanically protected or visibly surface clipped.

Sorry Wldgoose that is incorrect. A spur from a RFC for a single or double socket for only one point (at a time) does not even need a FCU. Cable route is different, as you say it needs to be surface mounted, in conduit or on an RCD if in the wall less than 50mm from the surface of both sides of the wall.

Its also a MWC as well.

 

[Octopus]

All as I thought, but just good to run things past more experienced sparks. I think best plan seems to be an external 30ma rcd mounted just outside where the fuse box is, then wire the kitchen ring to that before it goes back to the CU, to protect the whole kitchen.

Feel free to offer any better ideas.

Thanks

So do you have the BGB or the OSG?

 

[Hayd]

So do you have the BGB or the OSG?

I have OSG & BS 7671, yes am a spark was just really checking others thoughts on the best way on going about it. Took r1,r2&rn values , checked Ze and zs of current ring and insulation test when looking at the job. All values well within tolerance stated in OSG for fuse type. I have to move a couple of sockets as well so will already be taking responsibility for the whole circuit.

After scouring the forums most seems to think adding an external 30ma RCD then replacing the fuse with a plug in MCB the way to go.

 

[wildgoose]

Sorry Wldgoose that is incorrect. A spur from a RFC for a single or double socket for only one point (at a time) does not even need a FCU. Cable route is different, as you say it needs to be surface mounted, in conduit or on an RCD if in the wall less than 50mm from the surface of both sides of the wall.

Its also a MWC as well.

Correct it doesn't but it must have rcd protection and either the rcd spur or rcd socket would in that case be the most appropriate solutions.

The spur solution by the way is what was being asked about on the original post and not a socket.

 

[Sintra]

A kitchen ain't a special location.

 

[wildgoose]

But under Part P they group "Special Installations, Special Locations & Kitchens" all in the same section (5) ie:- those areas needing additional requirements and therefore requiring LABC notification.

 

[Sintra]

Yea see that I've just had a read of section 5. No real special requirements for a kitchen apart from the notification. Just glad I don't do domestic and especially not in England or Wales :lol:

 

[wildgoose]

You are right there! Must be a huge number of jobs-worths making a very nice living out of all these complicated regulations.

Apparently in Europe, there's a whole city dedicated to training and creating these people - it's called Brussels

 

[D Skelton]

Since when have SFCUs needed RCD protection?!?! If the cable is surface mounted then add an SFCU for each appliance and a flex outlet below.

Some people seem to think that you need to whack an RCD on anything with an electron! "Sorry sir, I can't change the socket for you because the RCD protecting it isn't RCD protected, and the regs need me to RCD protect the RCD protection protecting the RCD protection. Also sir, that wooden front door of yours, is that...."

 

[Hayd]

Since when have SFCUs needed RCD protection?!?! If the cable is surface mounted then add an SFCU for each appliance and a flex outlet below.

Some people seem to think that you need to whack an RCD on anything with an electron! "Sorry sir, I can't change the socket for you because the RCD protecting it isn't RCD protected, and the regs need me to RCD protect the RCD protection protecting the RCD protection. Also sir, that wooden front door of yours, is that...."

The cables are not surface mounted they are to be buried but not over 50mm, also some of the sockets are being moved, so therefore they will all need protection by RCD as I understand it as they will all be on the same circuit and the newly moved sockets can be used for portable appliances.

 

[D Skelton]

The cables are not surface mounted they are to be buried but not over 50mm, also some of the sockets are being moved, so therefore they will all need protection by RCD as I understand it as they will all be on the same circuit and the newly moved sockets can be used for portable appliances.

You have six options available to you then:

1. Protect cables buried in walls in galv conduit or earthed galv capping and add RCD socket outlets/RCD SFCUs protecting socket outlets.
2. Use FP200, MICC or SWA in the walls and add RCD socket outles/RCD SFCUs protecting socket outlets.
3. Utilise electrical seperation as your protective measure so you don't need RCD protection.
4. Get the homeowner to become a fully qualified electrician so he becomes a qualified person thus the install not needing RCD protection.
5. Change CU to incorporate RCD protection.
6. Add a stand alone RCD in line with the kitchen ring/radial circuit.

I know which two of those six I'd be leaning towards

 

[Deleted member 26818]

Can't use FP200, on it's own, would still need another acceptable method of additional protection.
The skilled or instructed person exemption does not apply to domestic premises, as there are no Statutory Requirements, which pertain to them.
pBit confused as to why the OP states they intend installing a plug in MCB.

 

[D Skelton]

I always thought FP had an earthed metallic sheath that would make it suitable for that purpose, not that I've ever used it for such purposes or even thought about it. With regards to the instructed person comment, it was clearly meant in jest, as was turning the customers kitchen in to an electrically separate installation

 

[Deleted member 9648]

Must be rcd protected fused spurs to meet regs. Also the cable from the ring to the rcd spurs, needs to be mechanically protected or visibly surface clipped.
I've previously converted the existing socket into a dual box (single socket with the rcd spur. This overcomes the connection wire difficulty above.

Finally, it's work being done in a kitchen so it must be LABC notified and that means a test report - easy if you are registered as you probably know??

Whats a test report?

 

[Deleted member 26818]

I always thought FP had an earthed metallic sheath that would make it suitable for that purpose, not that I've ever used it for such purposes or even thought about it. With regards to the instructed person comment, it was clearly meant in jest, as was turning the customers kitchen in to an electrically separate installation

It does have an earthed metallic sheath, unfortunately the cable is produced to a standard, not acceptable for it to be used in this situation.
The cables that would be acceptable, are manufactured to BS5467 (similar to FP200), or an SWA cable.
Yes I figured it was said in jest, but I figured, what the hell, I'm piping up about the FP, might as well remind people why we are not required to provide RCD protection in non-domestic installations.

 

[moose]

A Question ? when a Socket is for an applience does it not also state somewhere that if its a labeled item and not used for anything else, it can be used without RCD protection, as the item is getting added to the rear of the applience can you not state the RCD is not required for this socket as its behind the unit, but also add that there is a recommendation for future upgrade to the Property.

Im new to this principle, but i have seen the option somewhere, not sure its application...

 

[Deleted member 26818]

The requirement, is that sockets for use by ordinary persons and that are intended for general use, should be provided with RCD protection.
As such, a socket that is intended for a specific item of equipment (irrespective of who will be using it) does not require RCD protection.
There is an exception to the requirement for RCD protection, where a socket is intended for a specific item of equipment, and is labeled or otherwise identified as being for that purpose.
I don't understand why the wording of this Regulation hasn't been sorted out yet, the exception is clearly superfluous.

 

[D Skelton]

It does have an earthed metallic sheath, unfortunately the cable is produced to a standard, not acceptable for it to be used in this situation.
The cables that would be acceptable, are manufactured to BS5467 (similar to FP200), or an SWA cable.

I thought 5467 was SWA?

My understanding was that a cable buried in a wall had to be either suitably mechanically protected from penetration by screws, nails and the like or had to incorporate an earthed metallic sheath. SWA is never going to protect a cable from a screw or nail, it's armour is purely there (in the circumstance of being buried in a wall) to provide earthed protection to ensure ADS, as would the earthed metallic sheath of MICC, FP200 or suitably glanded SY?

Is it down to the csa of the armour/sheath? Obviously you can't use the FP's or SY's metallic sheath/braiding as a CPC unlike SWA or pyro. I'm guessing if it is unsuitable to be used as a cpc then it must be unsuitable to be used to protect the cable as a result of penetration damage?

Wish I had my BGB to hand as I love digging up little gems like this

 

[Deleted member 26818]

Sorry wrong end of the list.
Its BS8436 cables that are similar to FP.
Trade names such as flexishield, and guardian, probably others.
The metallic sheath and the CPC have to sufficiently robust to withstand a specific fault current caused by piercing the cable with a nail or screw.
As far as I'm aware, the metallic sheath on FP type cables provides protection against heat, it is not sufficiently robust to carry the specified fault current.

 

[D Skelton]

Ah yes, I've used Flexishield before in a hospital. From what I remember it wasn't much different from FP look and feel wise. I'm guessing it all comes down to product spec and testing. I guess FP hasn't been through/passed the same tests as Flexishield in order to gain 8436.

 

[Deleted member 26818]

As I recall, originally, flexishield was only suitable for low current applications, such as lighting, alarms and heating controls.
I understand they now have, and have had for some time, a product suitable for medium current applications such as socket-outlet circuits.
However, I'm not certain whether they have produced a suitable product for high current applications such as cookers or showers?

Yes it does look and feel remarkably similar to FP.
Probably can be used instead of FP?