Connection issue with swa

[Leejohnson222]

I need to run an out door supply.
However the dist board is boxed in.
There is access back entry but that doesn't help glanding a swa.
Could you gland outside to a through box them carry the same cable to the breaker?
Taking an earth leas from the conduit box also.

 

[Dave OCD]

Ok in that case a 16a MCB. But if it's going straight to an external rotary isolator you'd need the RCD protection at source for the tub.

 

[davesparks]

Depending on the fixed load a 2.5mm off a 32amp mcb is no different than spurring off the ring final directly from the Mcb at the consumer unit.
If overload protection isn't required then all the 2.5mm needs is fault protection which the mcb will give.
I personally would size the mcb so Ib<In<Iz but it wouldn't necessarily be a non compliance

It is different to a 2.5mm spur from a ring, this is a dedicated circuit to a single appliance and the spur from a ring is one point out of a number of points for general use. The ring circuit relies on loads being spread around the circuit to work correctly and it is advised that fixed loads greater than 2kW aren't fed via a ring circuit.

Yes you could prove by calculation that the mcb will provide fault protection for the cable, but this seems like an over the top and unnecessary thing to do for a domestic installation. Especially when you can guarantee that anyone who looks at this installation in the future will label you as a cowboy for having done it that way.

Far simpler to install an ocpd which is better matched to the load.

 

[davesparks]

Depending on the fixed load a 2.5mm off a 32amp mcb is no different than spurring off the ring final directly from the Mcb at the consumer unit.
If overload protection isn't required then all the 2.5mm needs is fault protection which the mcb will give.
I personally would size the mcb so Ib<In<Iz but it wouldn't necessarily be a non compliance

It is different to a 2.5mm spur from a ring, this is a dedicated circuit to a single appliance and the spur from a ring is one point out of a number of points for general use. The ring circuit relies on loads being spread around the circuit to work correctly and it is advised that fixed loads greater than 2kW aren't fed via a ring circuit.

Yes you could prove by calculation that the mcb will provide fault protection for the cable, but this seems like an over the top and unnecessary thing to do for a domestic installation. Especially when you can guarantee that anyone who looks at this installation in the future will label you as a cowboy for having done it that way.

Far simpler to install an ocpd which is better matched to the load.

 

[Ian1981]

It is different to a 2.5mm spur from a ring, this is a dedicated circuit to a single appliance and the spur from a ring is one point out of a number of points for general use. The ring circuit relies on loads being spread around the circuit to work correctly and it is advised that fixed loads greater than 2kW aren't fed via a ring circuit.

Yes you could prove by calculation that the mcb will provide fault protection for the cable, but this seems like an over the top and unnecessary thing to do for a domestic installation. Especially when you can guarantee that anyone who looks at this installation in the future will label you as a cowboy for having done it that way.

Far simpler to install an ocpd which is better matched to the load.

I hope you do realise that I'm not suggesting that it's spurred from the ring circuit, more suggested that if it was supplied from a 32 amp mcb on its own dedicated radial then as it's a fixed load it not necessarily no compliant as people are suggesting.
As stated I wouldn't use a 32 amp on a 2.5 , mearly suggesting it's no different being protected by a 32 amp as a spur is directly from the consumer unit when overload isn't a factor.
And yes the mcb will protect against fault protection you don't need a calculation to work that out.
Even a generic I2t let through value from a manufacturer will tell you that for a disconnection time under 0.1 of a second

 

[westward10]

Is a hot tub a fixed load.

 

[Ian1981]

It will I imagine have a maximum draw if you like
If it's rated 13 amp it's not going to pull 20 is it?

 

[davesparks]

It will I imagine have a maximum draw if you like
If it's rated 13 amp it's not going to pull 20 is it?

It will under an overload fault, it will not be a simple resistive load.

 

[Ian1981]

It wo

It will under an overload fault, it will not be a simple resistive load.

why will a 13amp supply overload a 2.5mm swa?

 

[davesparks]

It wo

why will a 13amp supply overload a 2.5mm swa?

That is not the question I was replying to, you asked if a load rated at 13A could draw 20A, which it could under an overload fault.

 

[Ian1981]

That is not the question I was replying to, you asked if a load rated at 13A could draw 20A, which it could under an overload fault.

Okay

 

[Leejohnson222]

The reason for 32 rcbo and swa 2.5
Is this is what the manufacturer required for installation. 32 does sound over boars but the is what they state in the paperwork before the delivery of the hot tub.

 

[telectrix]

does manufacturer say a 32A RCBO or a 32A circuit? what's the wattage rating of the tub?

 

[Wilko]

It will I imagine have a maximum draw if you like
If it's rated 13 amp it's not going to pull 20 is it?

My worry is that someone in the future will see the 32A mcb and attach more loads to the circuit.

 

[telectrix]

thing is... if the tub is rated @ 13A, why in hell is a 32A OCPD called for. only needs a 16A or 20A, then 2.5mm cable will comply in all ways.

 

[Ian1981]

My worry is that someone in the future will see the 32A mcb and attach more loads to the circuit.

Yeah but the circuit and installation in question should be assessed to see if it's adequate for alterations etc
Stick it on a 16amp and be done with it