Discuss Hi new to the forum! Conduit! in the Electrical Wiring, Theories and Regulations area at ElectriciansForums.net

Status
Not open for further replies.
G

Guest22

I have a question in terms in conduit, In conduit you use all the same size conductors in a circuit for a ring for instance, 2.5mm2 Line, 2.5mm2 Neutral and 2.5mm2 CPC.
Question, in T&E 2.5mm2 you have both line and neutral but CPC 1.5mm2, correct but, would it not be under regs to wire a 32 Amp radial in PVC conduit 4mm neutral and line, and a smaller CSA CPC?
Just a question :)
Cheers
 
Last edited by a moderator:

Deleted member 9648

Mentor
Electrician's Arms
Trainee Access
Messages
5,575
Location
south uk
I have a question in terms in conduit, In conduit you use all the same size conductors in a circuit for a ring for instance, 2.5mm2 Line, 2.5mm2 Neutral and 2.5mm2 CPC.
Question, in T&E 2.5mm2 you have both line and neutral but CPC 1.5mm2, correct but, would it not be under regs to wire a 32 Amp radial in PVC conduit 4mm neutral and line, and a smaller CSA CPC?
Just a question :)
Cheers
Do you?......CPC's are sized by either selection or calculation regardless of whether part of a cable or in conduit.
 

kingeri

Electrician's Arms
Messages
2,604
Location
Yorkshire
If your using singles I would youse same size cables for all
But you don't have to.

To answer the OPs question, yes it would be OK to use a smaller CPC with 4mm singles. The only issue I see with the scenario you've illustrated is that 4mm in conduit is derated to 30amps, so strictly you should not use a 32a protective device.
 

malcolmsanford

Electrician's Arms
Messages
7,375
Location
Kent working back out there yet again
But you don't have to.

To answer the OPs question, yes it would be OK to use a smaller CPC with 4mm singles. The only issue I see with the scenario you've illustrated is that 4mm in conduit is derated to 30amps, so strictly you should not use a 32a protective device.
Are you using table 4D2A there mate erection method B ?

I would be inclined to use Table 4D1A for single core cable erection method B and that would be the 32 amps for a single phase circuit. But then you would have all sorts of CCC rating calcs also to contend with
 
OP
N

nick611

i use the same size cpc as is in a twin and earth, ie 1.5 for a ring, 2.5 for a 6mm. why should it be bigger cause its in conduit ? the other guy are right though check you cable ratings and grouping factors when using conduit
 
OP
K

Knobhead

I take it, it’s PVC conduit you’re talking about. With metal I wouldn’t run a CPC at all.
 

ackbarthestar

Mentor
Electrician's Arms
Trainee Access
Messages
2,083
Location
A Zoo near YOU
Now since , it appears, nobody teaches the rudiments of metal conduit and wiring within such a containment then the chances are that the job will not be done correctly which would leave one up a so called creek without the necessary implements to redirect oneself.

It is normal practice to apply table 54.7 to final circuits and 543.1.3 to those who get off on square roots and strange R2s
 
OP
E

Engineer54

it appears, nobody teaches the rudiments of metal conduit and wiring within such a containment
Isn't that the shameful truth!!!
 

somersetsparks

Regular EF Member
Messages
1,251
I use the conduit as cpc when left to my own devices, especially when working for myself, it saves time, money, you can usually use smaller tube for each run etc. However I always tighten bushes and couplers correctly and use knurled locked rings and silcone grease at every joint.

You get the best R2 reaqdings you could ever hope for!
 
OP
E

Engineer54

I always tighten bushes and couplers correctly and use knurled locked rings and silcone grease at every joint.
I was always led to believe that ''silicone grease'' was non-conductive??
 

somersetsparks

Regular EF Member
Messages
1,251
I was always led to believe that ''silicone grease'' was non-conductive??
The stuff i've got says its 'electrically conductive grease' comes in 1l tins and is light grey sort of colour, I suppose it could be a different formulation as it is slightly greyer then the small tubes of rs silicone grease I've got. I
 
Status
Not open for further replies.

Permanent unswitched live colour?

  • Brown

    Votes: 46 65.7%
  • Black

    Votes: 24 34.3%

Electrician Talk

Top