RCD spur from ring main to (ip?) sockets for washing machine

jtonthebike · 10 Mar 2014

Hi all,

we have recently purchased a property and I want to add a plug socket to supply a washing machine. The washing machine will be mounted on the other side of a full height wall where there is a water supply for both the washing machine and a fridge/freezer.

I understand that in this environment, i'd need to use an RCD instead of a fused switch? I had selected metal-clad sockets but now suspect it may be best to use IP rated sockets?

The water supply pipe runs from right to left and across the left wall (to the water filter) and I'd intended to mount the RCD + IP sockets above the copper pipe. Is there a specific separation distance between copper and plug sockets / RCD?

When tapping into the ring, I had intended to do this below finished floor using a junction box as I have done previously (about 8 years ago in my last house) is this still considered acceptable practice?

We intend to get a new kitchen put in in a year or two, but i'd like to make sure the work I do is above 'basic' standards so that not only is it safe, there should be no issues when the kitchen is changed and electrically certified.

many thanks.
Jonathan

jon47 · 10 Mar 2014

jtonthebike said:
Hi all,

we have recently purchased a property and I want to add a plug socket to supply a washing machine. The washing machine will be mounted on the other side of a full height wall where there is a water supply for both the washing machine and a fridge/freezer.

I understand that in this environment, i'd need to use an RCD instead of a fused switch? I had selected metal-clad sockets but now suspect it may be best to use IP rated sockets? You could consider a suitably IP rated FCU or socket if there is a risk of water ingress and perhaps consider covering the whole circuit with an RCD

The water supply pipe runs from right to left and across the left wall (to the water filter) and I'd intended to mount the RCD + IP sockets above the copper pipe. Is there a specific separation distance between copper and plug sockets / RCD? Yes it is in the On Site Guide, you should get yourself a copy if you want to do electrical work it is only 20 pounds

When tapping into the ring, I had intended to do this below finished floor using a junction box as I have done previously (about 8 years ago in my last house) is this still considered acceptable practice? All joints should be accessible unless you use maintenance free JBs

We intend to get a new kitchen put in in a year or two, but i'd like to make sure the work I do is above 'basic' standards so that not only is it safe, there should be no issues when the kitchen is changed and electrically certified.

many thanks.
Jonathan

jtonthebike · 10 Mar 2014

Awesome, thanks. (used) Book ordered from Amazon for £16

The kitchen circuit (ring main) has an MCB (in the CU)... so ... if i do it like this:

MCB'd kitchen ring main --> RCD --> double IP rated socket with integrated RCD:- plug in washing machine.

I'm not in a desperate rush to complete the work as I want it done right, so will confirm heights/distances once the book has arrived.

I had intended to use maint' free junction boxe(s), something like this: http://www.electricbase.co.uk/hager-ashley-j803-17th-edition-maintenance-free-junction-box-32a.html ?

Thank you for your reply Jon47

ericmark · 10 Mar 2014

If there is no RCD on the ring already then to extend you are limited by 2008 regulations.

1) Use a RCD FCU at the point you intend to tap into existing ring and extend as a fused spur.
2) Use special cable Ali-tube and RCD sockets.
3) Change part or all of the consumer unit parts to give RCD protection to whole of final ring.

Buried cable in a wall now needs protection not just the socket so either special cable or RCD at origin of new wiring.

So first step is to consider what may be required in the future? Although you can get around this one why pay for RCD FCU or socket which will latter become redundant.

Step one is look at the consumer unit. Some do not have the room or design to fit RBCO's in which case it's all or nothing. Others do have the room so simple matter of swapping a MCB for a RCBO and you have RCD protection.

There are always other options including fitting a sub consumer unit fed from original with RCD protection but in the main cost of swapping whole consumer unit against cost of sub board just not worth it. However that's exactly what was done with my mothers kitchen and the sub-board is in the kitchen.

As to water in sockets problem one would hope water leaks are rare and with RCD protection if it does happen it will fail safe.

ericmark · 10 Mar 2014

Read your reply after posting do remember it is nearly impossible for any DIY work to fully comply with regulations simply as your unlikely to have test equipment. A socket tester like this

with loop test is about the best any DIY guy is going to stretch to still not full testing but going a good way towards it. Also some form of ohm meter to check ring is in fact a ring.

jtonthebike · 10 Mar 2014

Thanks for the heads up and info.

The CU was replaced in 2005 ... I may have my MCB and RCD confused...

I have a good quality Fluke DMM i'm confident in using, so that's it partly taken care of. In terms of that Martindale EZ Check, would you/someone have any suggestions as to where is best (cheapest) to buy one?

Yeah, I appreciate that it's not going to be at the same level as a professional test, but, so long as when Mr/Mrs spark arrives and doesn't suck through their teeth and grimaces, well, I'd rather have some level of praise/admiration for the quality of work, but still, I would rather spend time ensuring the planning is correct as the actual connection grunt work is straight forward enough.

jon47 · 10 Mar 2014

Test equipment should be calibrated. A good quality DMM which tests milli ohms and mega ohms combined with the knowledge of how to test circuits fully will give more of an indication than one of those plug in testers. you won't be able to test an RCD or test Ze, Zs (except by calculation and asking the supplier what their expected Ze is) or PFC without purchasing an MFT such as the Megger 1730 or the Fluke or Metrel versions.

jtonthebike · 10 Mar 2014

Unfortunately, the kitchen is just ran from the 'ground floor sockets' ring main. I think when the time comes, the kitchen will have it's own RCD in the CU as both me and mrs enjoy cooking.

Mind you, I also want to add dedicated supplies for my hifi and then another one for all my computing/networking kit, but that's another topic for another day.... though slightly related. What about using over-specced cable? I have a 16amp round pin socket + plug going to an 10 way extension cable, I have some 6mm T&E I was going to use, is that OK?

thanks.

jtonthebike · 10 Mar 2014

Yikes, don't think I can afford one of those Megger units, jeez that's a lot of cash. Though if it's your job, i'd have thought they're essential.

My Fluke meter was checked / calibrated about 18 months ago so is ready for doing again, in saying that, it was pretty much spot on when it went in so i'm not too worried about it.

I've had my head in a lot of other, but very different subjects as of late, would you have any sources for articles / web links to the subject of effective domestic circuit testing? While the mathematics of electrical theory was never my strong point, I can figure it out ... however i'd rather have just the info I need to ensure that what I am doing and testing gives expected results.

In terms of earth bonding, and I haven't looked at this for some time so please bear with me, where would i take that bond from? i can see bonding from pipe to pipe in the kitchen (water, no gas in kitchen) yet the boiler and pipework in the bathroom have no bonding. So i'm unsure as to whether I need to establish an earth connection to the copper where this washing machine will be, and if in doing so, can I simply tap into the new plug socket/rcd?

many thanks again.

Aragorn84 · 10 Mar 2014

MFT testers can be had for sensible money. I recently picked up a used Megger CM500 for £250 with a years calibration.

Guidance Note 3 details a lot of the testing, and would probably pair up quite nicely with the OSG you've already bought:

http://www.ebay.co.uk/sch/i.html?_f...nkw=guidance+note+3&_sacat=See-All-Categories

As for your bonding, you should have main bonds from the gas and water pipes as they enter the house back to the main earth terminal for the installation, which is typically either in or near the Consumer Unit.

jtonthebike · 10 Mar 2014

http://www.amazon.co.uk/gp/offer-listing/1849192758/ref=dp_olp_new?ie=UTF8&condition=new

seems I have some more bed time reading sorted

haha!

thanks v.much.

I very nearly bought a Fluke network systems tester, that was a really cool bit of kit, testing and certifying data cabling and it's performance. Sadly the £400 needed to be spent elsewhere.

Thanks for the heads up on the bonding. I did have a fuzzy memory that there didn't need to be earth bonding on *everything*.

right, time for theory and planning before I go spending on kit. Will try and remember to update this post and say how it went / report any issues.

thanks to all who have replied so far, I'm really pleased I asked rather than just bang a socket on the wall

diynot

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RCD spur from ring main to (ip?) sockets for washing machine

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