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Old 09-14-2008, 07:09 PM   #1
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Ring Main Question


Hello All,
I am currently having a new boiler fitted after the old one expired. The old boiler was in a cupboard downstairs which I will be converting into a new space in the kitchen for a tumble drier and freezer. The new boiler will be fitted into the airing cupboard upstairs. I've done a lot of the work myself (wet stuff, tanks etc, but am getting a corgi guy/plumber in to fit boiler flue,gas etc,commissioning and certification)

The supply for the old boiler came from a fused switch in the cupboard. I have taken the switch off and found I have three "wires" in it on the input side and the output side to the old boiler (with a 13A fuse!!). I've traced the wires to the floor space upstairs but cannot see where they go.

The house has what seems to be a single ring for the sockets (don't know if it's radial, any quick way to tell?), only a single breaker for sockets (no separate upstairs or downstairs ring)

I'm assuming that the three wires in the switch are ring-in, ring-out and spur) I know that if I meter them and switch the socket breaker off on the consumer unit they go dead.

My plan is as follows.

1. Switch off socket breaker
2. Disconnect the three wires and then switch on socket breaker to identify which are ring-in and ring-out and spur.
3. Install 4 way junction box into roof/floor space (depending on whether you are upstairs or downstairs)
4. Pull the ring wires up and connect into junction box.
5. Pull spur wire up and connect into junction box.
6. Connect new wire down to old location (new spur) and install double socket (for planned tumble/freezer)
7. trace ring wire back to under airing cupboard (can actually see)
8. Install 3 way junction box
9. Put new spur on fused switch (3A) into airing cupboard for new boiler.

I have already put a y-plan wiring centre in airing cupboard for all the other bits of the central heating.

Hope this makes sense, the house is about 32 year old so all old red/black wiring. I had a new consumer unit put in when I moved in 2 years ago so there is space for additional MCB's etc if needed.

Thanks

Andy

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Old 09-14-2008, 07:38 PM   #2
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Sounds like a UK electrical question. This site is mostly dedicated to USA and Canada. If you wait someone from UK might come by help you out.

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Old 09-14-2008, 09:39 PM   #3
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Like Joe said, someone knowledgeable in UK systems may come along to help you, but you might find this site useful too. I believe they have a forum also.

http://www.diydoctor.org.uk/projects.htm
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Old 09-14-2008, 10:24 PM   #4
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Quote:
The supply for the old boiler came from a fused switch in the cupboard. I have taken the switch off and found I have three "wires" in it on the input side and the output side to the old boiler (with a 13A fuse!!). I've traced the wires to the floor space upstairs but cannot see where they go.
Many accessories require protection at a lower current than the MCB protection device. A 25 mm ceramic cartridge fuse, rated at 3 A, 5 A, or 13 A is commonly used depending on the protection rating of the equipment. It sounds like the old boiler spur may have been over-fused by your description.


Quote:
The house has what seems to be a single ring for the sockets (don't know if it's radial, any quick way to tell?), only a single breaker for sockets (no separate upstairs or downstairs ring)
A radial circuit is one where the power is transmitted from device box to device box by a single length of cable linking each point to the next. It starts at the MCB switch or fuse and simply terminates at the last connected device. It may branch or spur at a connection points. Almost all your lighting circuits are done with this method. However you may find low current sockets supplied in this manner also.

The ring circuit is rather unique to the UK. You have a cable that starts at the supply point and goes to each device pretty much like a radial. However the last device is connected back to the supply so that the whole circuit forms a loop or ring. The reasoning for this is to allow more wattage to be supplied than could otherwise be carried with a given size of cable.

Quote:
I'm assuming that the three wires in the switch are ring-in, ring-out and spur) I know that if I meter them and switch the socket breaker off on the consumer unit they go dead.
Hard to say have you determined which are live and neutral and earth?

Quote:
My plan is as follows

1. Switch off socket breaker
2. Disconnect the three wires and then switch on socket breaker to identify which are ring-in and ring-out and spur.
3. Install 4 way junction box into roof/floor space (depending on whether you are upstairs or downstairs)
4. Pull the ring wires up and connect into junction box.
5. Pull spur wire up and connect into junction box.
6. Connect new wire down to old location (new spur) and install double socket (for planned tumble/freezer)
7. trace ring wire back to under airing cupboard (can actually see)
8. Install 3 way junction box
9. Put new spur on fused switch (3A) into airing cupboard for new boiler.

I have already put a y-plan wiring centre in airing cupboard for all the other bits of the central heating.

Hope this makes sense, the house is about 32 year old so all old red/black wiring. I had a new consumer unit put in when I moved in 2 years ago so there is space for additional MCB's etc if needed.

Yes that sounds fine, main thing is to make sure fusing is correct so that amperage does not exceed the mcb or any switch to device fusing doesn't exceed the equipment ratings.

Remember your earth to live is 230 volts... so power off mate.... when your working on this......

Last edited by Stubbie; 09-14-2008 at 10:43 PM.
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Old 09-14-2008, 10:38 PM   #5
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I'm glad you responded to this thread Stubbie. I like learning about the UK/Euro systems. Where did you acquire this knowledge?
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Old 09-14-2008, 10:47 PM   #6
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Most of what I know is from reading and reading and reading using the internet.

And quite a bit comes from here.......


http://www.electriciansforums.co.uk/...s-regulations/

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