Cable leaving house to underground.

[EFLImpudence]

I'll try again:

1. Does any cable, as it leaves a house, need additional fuse protection at that point - is there a reg stating so?

No, but it might need fuse protection for other reasons.

2. Is the mcb/rcbo at the CU good enough?

Yes, if the cable is good enough.

 

[hard-work]

I'll try again:

No, but it might need fuse protection for other reasons.Yes, if the cable is good enough.

Thanks.
Easy wasn't it?

 

[EFLImpudence]

Thanks. Good we are getting somewhere

Or nowhere fast.

Of course it cannot have more than one socket off spur.

Why not?

If the cable runs say into a garage, the garage CU will take care of all inside. As there will be a main fuse/mcb in the garage, it can be split into sub circuits after - sockets, lights.

No point having a CU on a spur.

 

[Taylortwocities]

Ahh no. you connect a “garage cu” to a spur because the load on the spur can be more than the permitted current.
you might, incorrectly, add a ring final in the outbuilding Connected to a 32A MCB in the outbuilding.

As above. You can run a spur from a ring final. It can connect only to an FCU(Max 13A) or to a single or double socket outlet.
NOT directly to another DB.

 

[bernardgreen]

the garage CU will take care of all inside

Will it ?

 

[hard-work]

Ahh no. you connect a “garage cu” to a spur because the load on the spur can be more than the permitted current.

If say a garage CU has protection for the spurred cable (say 2.5mm) all is fine. The 2.5mm cable can take up to 27 amps. 20A protection in say a garage CU, covers protecting that spurred cable off the 32A ring.

As above. You can run a spur from a ring final. It can connect only to an FCU(Max 13A) or to a single or double socket outlet.
NOT directly to another DB.

Thx. Is there a reg stating that max is 13A?

To be sure a 13A mcb (they are available) in a garage CU with a 3A lights and 10A sockets MCBs off that?

 

[hard-work]

Or nowhere fast.

Only on your part. The Q was quite simple.

 

[DetlefSchmitz]

Jeez.

 

[hard-work]

Jeez.

More noise. Why do they bother?

 

[hard-work]

Will it ?

Done properly, of course it will.

 

[winston1]

If say a garage CU has protection for the spurred cable (say 2.5mm) all is fine. The 2.5mm cable can take up to 27 amps. 20A protection in say a garage CU, covers protecting that spurred cable off the 32A ring.
Thx. Is there a reg stating that?

To be sure a 13A mcb in a garage CU with a 6A lights and 10A sockets MCBs off that?

What? Why would you need a 10A sockets MCB? They can be run straight off the 13A one.

Lets start again. A spur can have one single or double socket or one FCU. After the FCU you can do what you like within reason.

So, an FCU in the garage feeding all the sockets and also feeding a switched FCU with a 5A fuse as your light switch.

 

[hard-work]

Thanks. OK it has been determined that when a cable leaves a house to go underground, no fusing is needed at the point of leaving the house. That is my Q answered.

OK, now, the spur off the ring can only be protected by a maximum of 13A fuse/msb protection? Is that clearly so?

 

[EFLImpudence]

More specific questions would get more specific answers rather than the yes/no you seem to want.

To be helpful:

Thanks. OK it has been determined that when a cable leaves a house to go underground, no fusing is needed at the point of leaving the house. That is my Q answered.

Not at the point nor because it is leaving the house but a fuse might be required; the same as for any other cable anywhere.

OK, now, the spur off the ring can only be protected by a maximum of 13A fuse/msb protection? Is that clearly so?

No, but if you use an FCU, 13A is the maximum rating made for them.
You will have to have an FCU somewhere, or MCB to the cable rating in a CU in the garage, if you don't install the circuit so that it is not necessary; the same as one is not necessary when the circuit enters the kitchen (or wherever the spur is connected).

Why not use a cable that doesn't need any protection?

 

[scousespark]

What appliances do you tend to use? That drives the design.
You need to calculate the load.

 

[hard-work]

Not at the point

sorted.

No, but if you use an FCU, 13A is the maximum rating made for them.
You will have to have an FCU somewhere, or MCB to the cable rating in a CU in the garage,

First part answered. Now interesting. As thread went on, the point of spurs on a ring being protected by only a maximum of 13A, even though the spur cable is rated 26A, came up.

Scenario.

• A 32A ring, 2.5mm cable.
• Junction box in ring then 2.5mm to a garage or out-building.
• In garage/out-building a small CU.
• CU has a 20A MCB/fuse protecting the garage/out-building and the 26A rated spur cable.
• Spur cable protected as it is rated at 26A - all safe.
• After the 20A mcb, which protects the whole garage/out-building, a couple of 16A radials for sockets, say one for inside and for the outside for garden socket use.
• Another mcb at 3A for LED lighting.
• Circuits off garage/out-building split, so divide & rule.

Looks very legal to me now. Clearly electrically sound and safe for sure.