New Cable to Old

[trebor]

I have been asked by my brother to take a spur from the ring main to a summer house from the house (7m) T&E. BUT I have since found out that the house has not be rewired for about 40yrs. Is it safe to connect a 2019 T&E to an older Ring main. Consumer main fuse 45A

 

[telectrix]

I have been asked by my brother to take a spur from the ring main to a summer house from the house (7m) T&E. BUT I have since found out that the house has not be rewired for about 40yrs. Is it safe to connect a 2019 T&E to an older Ring main. Consumer main fuse 45A

perfectly safe as long as the existing cable is in sound condition. more importantly is what cable are you intending to use for the spur; what, if any containment do you propose; what load will it feed; are you fusing down with a FCU; and finally, have you the test gear to test the work, and are you competent to do it?

 

[Spoon]

Is it safe to connect a 2019 T&E to an older Ring main. Consumer main fuse 45A

Are you saying that the ring main breaker size is 45A?

 

[telectrix]

Are you saying that the ring main breaker size is 45A?

missed that.he could be confused with a cooker or shower circuit. another thing i missed was to ask if circuit was RCD protected. i blame lack of sleep/food/beer.

 

[Pete999]

perfectly safe as long as the existing cable is in sound condition. more importantly is what cable are you intending to use for the spur; what, if any containment do you propose; what load will it feed; are you fusing down with a FCU; and finally, have you the test gear to test the work, and are you competent to do it?

Providing the JB if used is Accessible, if not MF, if taken from an existing socket outlet, that is part of the RFC and not a spur, how many sockets are intended to be installed in the Summer house? more than 1 then a fused spur should be used at the take off from the RF, as per Appendix 15 BS7671.

 

[James]

T + E might not be the best cable for running to an outhouse.
Have you considered something a little more robust?

 

[trebor]

I have been asked by my brother to take a spur from the ring main to a summer house from the house (7m) T&E. BUT I have since found out that the house has not be rewired for about 40yrs. Is it safe to connect a 2019 T&E to an older Ring main. Consumer main fuse 45A

Thank you all... great help
45a is the main breaker.. ring main 16a down and 16a upstairs,
Summer House has Hot Tub 10a (6a Heat and 4a pumps etc) 2 lights, one radio, fridge 1.5kw oil heater with a 2kw fan heater for boost.(as when required)
Was thinking about putting 2.5mm T&E in a conduit. SWA I felt would be an issue connecting it to Ring Main in doors. Max distant is 7m.. Cable is at the side of house well shaded. Taking the cable 3 foot off the floor
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I have been asked by my brother to take a spur from the ring main to a summer house from the house (7m) T&E. BUT I have since found out that the house has not be rewired for about 40yrs. Is it safe to connect a 2019 T&E to an older Ring main. Consumer main fuse 45A

sorry I forgot to mention one Double socket

 

[James]

That sounds like too much current for 2.5mm and more than you can run off a spur.
Have you done any calculations?

I would have thought it would merit being on its own new circuit.

 

[James]

Ps are you sure about the main fuse being 45A?
I have seen old properties with 60A supplies but never less than that.

You are looking at adding
10A hot tub
8A fan heater
6A oil heater
2A fridge (estimate)
13A double socket (estimate) patio heater etc
Call that little lot 40A and it is almost the total of the incoming supply.

You say you are a trainee, why not use this as an exercise in how to plan and calculate a new installation and see what you come up with.
There are loads of us on here that will give you pointers and show where your calls might not be correct.

 

[telectrix]

as above this looks like should be on it's own circuit from DB/CU.

 

[trebor]

Ps are you sure about the main fuse being 45A?
I have seen old properties with 60A supplies but never less than that.

You are looking at adding
10A hot tub
8A fan heater
6A oil heater
2A fridge (estimate)
13A double socket (estimate) patio heater etc
Call that little lot 40A and it is almost the total of the incoming supply.

You say you are a trainee, why not use this as an exercise in how to plan and calculate a new installation and see what you come up with.
There are loads of us on here that will give you pointers and show where your calls might not be correct.

Thank you for your help.
What started out as great challenge is now becoming a full on challenge.
I had worked out 24a without the fan heater full on throwing everything over the top. I am not confident to plumb in a 16a breaker into the main consumer board. As you can see it would need to be replaced.
I thought if I spur off the ring main and put a 13a 2g RCD switched plug socket in and advise him to have the house rewire then it could have a direct cable from the consumer box. I am aware the switch will trip if he starts pulling to much heat. THIS has all started because of the cold winter nights. The overload are the heaters.
Again, really many thanks to you all

 

[James]

That 45A fuse holder is not the main fuse.
I think you are looking at a new board to support what you are intending.
I also can’t see any rcd there.

This really needs planning correctly to ensure everything is safe.

 

[freddo]

Where are you looking? The fusebox appears to have one, maybe 2, ring finals on 30a MCB(s) (not 16A, The 45a could be for a shower or cooker, it certainly isn't the main supply fuse... Needs RCD protection too.
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Edit, as a general rule, those fuseways are not designed for fuses over 30A. Some models had a separate high current way for such things, some of the ones that didn't had a high current way nearest the main switch. You can tell if the way is designed to take higher current fuses/mcbs as the contacts have separate silver colour contact springs, each held on with a pair of small screws.

 

[davesparks]

. I am not confident to plumb in a 16a breaker into the main consumer board. As you can see it would need to be replaced.
I thought if I spur off the ring main and put a 13a 2g RCD switched plug socket in and advise him to have the house rewire then it could have a direct cable from the consumer box.

You can't add another mcb to that board because there are no spare ways.
Also there is nothing you have said so far that suggests a rewire is necessary, a full inspection and test along with replacing the CU would be the most you could advise at this stage.

It is not necessary to rewire a house just because the cable is a different colour,

 

[MJPD29]

7mm cable? Are you sure that's right? Providing you have tested the circuit with your mft and everything is ok then yeah it's fine to connect to it. Presumably through a 13a spur?

 

[westward10]

7mm cable? Are you sure that's right? Providing you have tested the circuit with your mft and everything is ok then yeah it's fine to connect to it. Presumably through a 13a spur?

I believe 7m is the distance and not the cable csa.