Just a thought on RFCs

[Pete999]

After reading a post yesterday regarding a Timber House Install, got me wondering, someone mentioned, can't remember who it was, and asked has anyone ever wired a RFC in 4mm2 cable, now I have never gotten involved in all this fancy Timber all insulated structures, so I asked myself the question, "if after all calculations", you came to the conclusion that normal 2.5mm2 RFC was, or did not meet the requirements after applying all the derating factors, you needed to install 4mm2 instead of 2.5mm2, how would you note the distraction from the, norm, would you just add a note on the certificate? describing what and why you had installed the circuit in this way. Just asking out of interest.

 

[Ian1981]

Think I mentioned it pete.
I wouldn't personally mention it as the reference method on the test sheet notes this,whether it be ref 101 or perhaps 103 for in walls should give someone an idea(an electrician perhaps) why it's in 4mm

 

[LankyWill]

Can't see why you would need to note it, as long as it's written in the csa size box on the eic.

 

[Octopus]

If the RFC isn't supplying the kitchen or utility maybe a 20A breaker is the way to go on the 2.5mm

That said, whats then to stop some muppet in the future installing a 32A breaker?

A very interesting subject...

 

[telectrix]

If the RFC isn't supplying the kitchen or utility maybe a 20A breaker is the way to go on the 2.5mm

That said, whats then to stop some muppet in the future installing a 32A breaker?

A very interesting subject...

then again, what's to stop some muppet replacing a 32A on a standard 2.5mm RFC with a 50A?

 

[Pete999]

Think I mentioned it pete.
I wouldn't personally mention it as the reference method on the test sheet notes this,whether it be ref 101 or perhaps 103 for in walls should give someone an idea(an electrician perhaps) why it's in 4mm

Yes thought that would be the best option, just interested that's all.

 

[Pete999]

then again, what's to stop some muppet replacing a 32A on a standard 2.5mm RFC with a 50A?

You mean one of the latest crop?

 

[Octopus]

then again, what's to stop some muppet replacing a 32A on a standard 2.5mm RFC with a 50A?

Bob the builder uses a populated board and any combination of connections and cables - nothing stops them!

 

[Ian1981]

Put it this way when I say to my boss I need 4mm not 2.5mm because of thermal insulation his face drops quite a bit
Then he sends someone else to do it who doesn't realise the effects of thermal insulation to cables

 

[Pete999]

Put it this way when I say to my boss I need 4mm not 2.5mm because of thermal insulation his face drops quite a bit
Then he sends someone else to do it who doesn't realise the effects of thermal insulation to cables

If that's the case then your Boss want's re educating, or giving up the job.

 

[Flanders]

Used 4mm for ring circuits with long runs on commersial installs and 2.5 mm for lighting circuits , makes connecting up click roses difficult though when you use 2.5mm , we just fill out the certs with the relevant details

 

[westward10]

See plenty of 4.0/4.0 ring finals doing PIRS.

 

[davesparks]

It's common on commercial specs to standardise lighting as 2.5mm minimum size and small power as 4mm minimum size. This is done to negate grouping factors and make calculations quicker and easier.

 

[Pete999]

See plenty of 4.0/4.0 ring finals doing PIRS.

Not disputing that Westy just wondered how people document it that's all.

 

[D00DY_T00DY]

then again, what's to stop some muppet replacing a 32A on a standard 2.5mm RFC with a 50A?

I'm smart and only put a 45A on mine
Better safe than sorry