wiring in dado trunking

[nicsin02]

hi guys quick question, got sent out to a job today to connect in sockets that are lying on the floor in dado trunking for office computers etc, the whole room is wire in a ring protected by a 32a mcb to 5 seperate 20amp double pole switches, these switches feed about 5 or 6 sockets each on a radial, the electrician in before me wired an extra 16 sockets on to one of these radials meaning the douple pole switch is feeding 22 sockets, is this ok/ they are wired in 2.5mm single cables in trunking which can take 24a according to regs, so would the 20amp double pole switch blow if the radial load exceded more than 20 amps meaning the 24a cable will be protected, just making sure thanks

 

[ab1978]

hi
the double pole switch is rated at 20amp not fused, so would overheat not blow i'm afraid. i would consider changing the radial with 22 sockets on it. don't understand why some would wire it that way to be honest

 

[Guest123]

I'd be a lot more worried about overloading the RFC at that point as technically there are now 22 spurs!!!!!

 

[Swicade]

Surely each 20a double pole switch should be seperately fused when spurred off the ring the way it is now.......

Seems to me a totaly bad install without the extra 16 sockets....the way i read it there's a total of 42+ spurs off a ringmain? (4x 5-6 sockets + 1x22 sockets)

 

[Strima]

Sounds like a right bag of spanners and a fire waiting to happen.

 

[Guitarist]

Firstly, you are only allowed as many spurs off an RFC as you have sockets on it. Secondly, if I'm reading it correctly, you have several spurs off spurs, which is totally unacceptable unless they are fed from a 13 SFCU from the RFC. This sounds like it needs redesigning asap.
Your question "

so would the 20amp double pole switch blow if the radial load exceeded more than 20 amps meaning the 24a cable will be protected, just making sure thanks" has made me very worried....​

 

[Adam W]

If you're after a quick fix you could replace the DP switches with FCUs, but ideally it wants redoing properly.
By 'properly' I mean conventionally, not trying to be 'clever'.

 

[trev]

In your position I'd be thinking about the load and how it could be spread around the RFC and splitting the suite up so it could be better served by more than one circuit.
Either that or, as some of my learned friends have implied, get some fire extinguishers in there

 

[Farmelectrics]

Have you give any thought for high integrity earthing that all pcs require

 

[needasparks]

Would it not be easier to introduce another leg to the 22 points and make it a ring on its own if the board is not too far away.

 

[nicsin02]

sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch i would have fought it would stop the cable exceeding 20 amps of current, the sockets only have single earthing aswell!!:banghead:

 

[Guest123]

sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch

Thats just the maximum rating of the contacts of the switching mechanism. Anymore and they will start to overheat.

 

[nicsin02]

Thats just the maximum rating of the contacts of the switching mechanism. Anymore and they will start to overheat.

so what would u reckon would be the easiest way to fix this i have only an hour in this office 2morrow morning only thing i can think of is replacing swiches with fused spurs any ideas

 

[Guitarist]

sounds like a pretty ****ty install, so what does the "20 amps" actually mean on a douple pole switch i would have fought it would stop the cable exceeding 20 amps of current, the sockets only have single earthing aswell!!:banghead:

Are you really working on electrical systems without knowing the difference between a switch and circuit protection? Please tell me you are just teasing.

 

[nicsin02]

Are you really working on electrical systems without knowing the difference between a switch and circuit protection? Please tell me you are just teasing.

simple mistake:sick: just have to replace with a fused spur and hope they dont exceed their 13 amp allowance