# Forum Home Renovation Electrical  Maximum breaker size for 4.0mm2 2C+E cable?

## craigj-au

Hi. 
Just wondering what is the maximum breaker size for 4.0mm2 2C+E cable? Is it 32A or actually lower than that? 
Thanks! 
Craig

----------


## BRADFORD

The answer to that question is  
It depends.

----------


## craigj-au

Hi. 
Depends on what? What I mean is, what is the maximum breaker size so that it protects the cable? I guess the other way to ask the question is what is the maximum current rating for 4.0mm2 cable? According to ANZ regulations etc. 
Thanks, 
Craig

----------


## Bros

Depends on distance and size of earth.

----------


## Uncle Bob

> Depends on what?

  Basically the temperature the cable can handle. It can be de-rated by being in a bundle, if it has insulation covering it, how it's installed etc. 
Sparkies have tables to look this stuff up (or should have  :Wink:  ).

----------


## craigj-au

So if it is common 4.0mm 2c+E flat cable, all conditions ideal, what is maximum? Say 15m run in a house. I'm guessing depending on conditions, it can get lower (not higher), but what is maximum usually installed? 32A? 25A? 
Thanks.

----------


## Bros

35A max less the downgrading factors

----------


## Bruiser

+1 for 35A.  Multiply that by 0.75 if you're into a bit of insulation or sunlight and a 20A breaker is probably the go.  15m is often 25m by the time you're up and down and at 20A your voltage drop will be just under 2.5% over this distance.

----------


## Random Username



----------


## craigj-au

Thanks for the table!

----------


## oldtrack123

> Thanks for the table!

  
HI Craig
If you are an electrician you SHOULD know all that 
If you are not an electrician you should not be doing hard wiring!!
Now what ratng did you decide on from the tables?? 
Remember the old saying 
"A LITTLE KNOWLEDGE CAN BE DANGEROUS" 
PeterQ

----------


## craigj-au

> HI Craig
> If you are an electrician you SHOULD know all that 
> If you are not an electrician you should not be doing hard wiring!!
> Now what ratng did you decide on from the tables?? 
> Remember the old saying 
> "A LITTLE KNOWLEDGE CAN BE DANGEROUS" 
> PeterQ

  I'm not an electrician. I pay an electrician to get the work done. Often I buy the parts. I just like to try and understand how it all works. For particular upcoming situation probably we will use 25A, as it is for a 5.8kW cooktop, and max 15m actual cable inside run. But will leave it to sparky to make final decision. 
Thanks, 
Craig

----------


## Bros

You say you buy the parts but a word of warning there is to look at a previous post about the failure of a brand of TPS cable so if you do the buying he will not be responsible for any failures at a later date. 
If you think it is electrical and it is from an Australian supplier think again as there is some garbage on the market that is suitable for use on the Australian market but deficiencies don't come to light until a later date. At times you can pick rubbish when you are installing it but not always. As for the cable the manufacturer has gone out of business and the only recourse the end used (customer) has is the electrician who supplied and installed the gear. It is his problem as to how he gets recompensed but that's not your worry.

----------


## oldtrack123

> You say you buy the parts but a word of warning there is to look at a previous post about the failure of a brand of TPS cable so if you do the buying he will not be responsible for any failures at a later date. 
> If you think it is electrical and it is from an Australian supplier think again as there is some garbage on the market that is suitable for use on the Australian market but deficiencies don't come to light until a later date. At times you can pick rubbish when you are installing it but not always. As for the cable the manufacturer has gone out of business and the only recourse the end used (customer) has is the electrician who supplied and installed the gear. It is his problem as to how he gets recompensed but that's not your worry.

  
Hi All
 Bros's post is well worth reading 
Those cheap? components you buy at your local Hardware store may ended up costing you a lot! 
Just because they look OK or appear to be very similar to well known brands does not mean they have the quality. 
Recalls are issued regularly  for impoerted gear /components, due to premature & often potential FIRE hazards in service failures in service !!  
A major recent one was look alike Switchgear 
Appeared to be a Clipsal product in EVERY aspect, selling very cheap!! 
Buyer BEWARE  
PeterQ

----------


## craigj-au

> You say you buy the parts but a word of warning there is to look at a previous post about the failure of a brand of TPS cable so if you do the buying he will not be responsible for any failures at a later date. 
> If you think it is electrical and it is from an Australian supplier think again as there is some garbage on the market that is suitable for use on the Australian market but deficiencies don't come to light until a later date. At times you can pick rubbish when you are installing it but not always. As for the cable the manufacturer has gone out of business and the only recourse the end used (customer) has is the electrician who supplied and installed the gear. It is his problem as to how he gets recompensed but that's not your worry.

  Thanks, good point!

----------


## Brian7886

> Hi. 
> Depends on what? What I mean is, what is the maximum breaker size so that it protects the cable? I guess the other way to ask the question is what is the maximum current rating for 4.0mm2 cable? According to ANZ regulations etc. 
> Thanks, 
> Craig

  
4mm2 with a 32A would be pushing it. I dont usually put larger than a 25A on. Id upsize to 6mm for 32A.  
Off the top of my head, 4mm TPS flat would have a CCC of about 28 or 29A when run through a roof with insulation etc (heat being the de-rating factor here). It can carry well over 32A in a situation where its underground without other wires in the conduit etc.  
Like Bros said, it depends

----------


## tricky4000

Hey craigj-au, go with what Brian7886 said.  I'm not a sparkie myself but I remember my sparkie telling me he would use 6mm for our oven instead of 3mm or 4mm.  It was an 11m run from the switchboard and from memory it has a 32A breaker.  I can't remember how many watts the oven was but I do recall him saying to go a little bigger on the cable.  We have insulation in our walls, that's probably why.
Tricks

----------

