4 core fp200 ring circuit

[tester11]

Came across a 2.5mm fp200 4 core cable used as part of a ring today, am I right in thinking this isn't an acceptable method as there will be only 1 earth wire in the cable ??

 

[davesparks]

How was it being used?


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[tester11]

It has been used to extend the ring in part of a shop area mainly supplying pc's. There is a joint box with the 2 ends of the ring which are 2H2.5 mi's and the 4 core fp.

 

[davesparks]

So it's being used to carry both halves of the ring in one cable?

Then as I can see it you have two problems, one being that the cpc is not in a ring and therefore not compliant and the other being that fp200 offers none of the protection characteristics of mi and so is almost never suitable as a suitable means of extending such a circuit for normal lighting/power installations.


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[tester11]

Thanks, When you say offers none of the protection characteristics what exactly do you mean by that ? Do you mean if it is designed for MI then FP doesn't meet the design criteria that MI would give ?

 

[Risteard]

You will have a 2.5mm^2 cpc then (not a ring cpc).

However if I am understanding the setup correctly then you don't have a ring on either of the live conductors emanating from the adaptable box either but rather parallel conductors.

 

[davesparks]

Thanks, When you say offers none of the protection characteristics what exactly do you mean by that ? Do you mean if it is designed for MI then FP doesn't meet the design criteria that MI would give ?

I mean it does not have the same mechanical, thermal or electrical protection. The mi will also have a higher current rating, different temperature rating, different volt drop and a much bigger cpc

 

[tester11]

Got you, nah they are a ring as the conductors are connected in two separate pairs in the joint and not all together.

 

[tester11]

Ok, everything is clipped direct onto a block wall and is only about 5 metres of the 4 core used so there is still probably adequate protection for what you mention but I definitely agree with the Earth wire issue.

 

[bigspark17]

Came across a 2.5mm fp200 4 core cable used as part of a ring today, am I right in thinking this isn't an acceptable method as there will be only 1 earth wire in the cable ??

What was the other cable used in the rest of the ring.. T&E.? How many sockets have been run in the 4c fp.?

 

[Darkwood]

Why is the original in MI cable?

Is it a spec'd requirement on the original design i.e. Council property where higher durability and lower maintenance, maybe the tenants etc got in their own Electrician who side stepped any requirements additional to the regulations.

Been a shop may have meant Building Control and fire safety have specified MI is used and this needs to be looked into as the previous 'electrician' may have undertaken work breaching BC requirements.

Agree with others regarding the earth, bad design at the very least even if Zs is still met.

 

[Risteard]

nah they are a ring as the conductors are connected in two separate pairs in the joint and not all together.

But how are they connected at the additional socket outlets?

 

[Deleted member 26818]

Is the go a part of the ring, or a spur from the ring?

 

[Megavolt]

Dont see a issue with it. When I did some training they was the ones who put me on to it.