Cross sectional area current capacity

G

Gardner

How would you go about figuring the current carry capacity of 2.08mm2 copper conductor? In so far no reg tables have none standard size.
 
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You could always use the lower value as for a 1.5mm copper conductor or enquire of the manufacturer?

I reckon the main question would be why would you need value for a 2.08mm conductor? Quite a specific request, if it is new ask the supplier, if it is existing and installed how do you know it is 2.08mm?
 
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Easiest way is by enquiring of the manufacturer.
Otherwise use the nearest (smaller) standard size for that type of conductor and insulation.
 
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mattwoott said:
You could always use the lower value as for a 1.5mm copper conductor or enquire of the manufacturer?

I reckon the main question would be why would you need value for a 2.08mm conductor? Quite a specific request, if it is new ask the supplier, if it is existing and installed how do you know it is 2.08mm?
Click to expand...

2.08mm2 is written on the jacket. This adds an extra 0.58mm of conductor, but looking at the regs this is right in between 1.5 and 2.5mm2. Do I just take the current capacity in between the two?
 
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You are using a strange American type cable at the weird size of 14 AWG!!
:79::wink_smile:
It would probably not meet the UK specifications.

You would have to reference BS7769 (60287), BSEN60228 and IEC60502 to research the methods for current carrying capacity determination!
 
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davesparks said:
No because the relationship between ccc and csa is not linear
Click to expand...

Exactly my hesitation, my understanding is that smaller conductors can carry more current per weight than larger conductors due to smaller conductors have more surface area and in turn can conduct heat away better?
 
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Richard Burns said:
You are using a strange American type cable at the weird size of 14 AWG!!
:79::wink_smile:
It would probably not meet the UK specifications.

You would have to reference BS7769 (60287), BSEN60228 and IEC60502 to research the methods for current carrying capacity determination!
Click to expand...

You wouldn't happen to know what equation is used in other regs like the IEC? My understanding is, and I could be wrong, that table 4D5 and others were derived via thermodynamic equations made by the IEC.
 
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Too many variants to make a guess and best advice already given is seek the manufacturers guidelines on this one or rate it to the next similar lower sized cable and your pretty much covered.
 
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Gardner said:
You wouldn't happen to know what equation is used in other regs like the IEC? My understanding is, and I could be wrong, that table 4D5 and others were derived via thermodynamic equations made by the IEC.
Click to expand...
I would agree with the above posts about cable sizing too many variable in standards compliance and cable design.

However this webpage seems to discuss the methods used in IEC60287. I feel it is not worth working it out when the standard cables have been calculated (probably well on the side of caution!) for you.

Edit just found this
IEC METHOD
IEC 60287 provides method for calculation of current carrying capacity of cable for different design parameters of cable (cross section, thermal resistivity, thickness of layer … etc.) as well as for different environment (ambient temperature, soil condition, depth of cable, spacing of phases … etc.).The current rating (ampere) using in the IEC standard is:

CCC calculation IEC60287.jpg
where Δθ [[SUP]o[/SUP] C] is temperature rise between ambient temperature and cable conductor temperature, W[SUB]d[/SUB] [W/m] is dielectric loss of cable insulation, T1, T2, T3 [K.m/W] are equivalent thermal resistances calculated from the cable material’s thermal properties, T4 [K.m/W] is the cable external thermal resistance, R[SUB]ac[/SUB] [Ω/m] is the AC electrical resistance of the cable conductor at maximum temperature and λ1 and λ2 are the ratio of losses in the metal sheath to total losses in all conductors and the ratio of losses in the armouring to total losses in all conductors, respectively.
 
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Gardner said:
How would you go about figuring the current carry capacity of 2.08mm2 copper conductor? In so far no reg tables have none standard size.
Click to expand...

I would start by ripping this 2.08 mm or 14 AWG whatever it is straight out. Then replace with 1.5 mm or 2.5 mm depends what the load is.
 
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Richard Burns said:
.........The current rating (ampere) using in the IEC standard is:

View attachment 29359
where Δθ [[SUP]o[/SUP] C] is temperature rise between ambient temperature and cable conductor temperature, W[SUB]d[/SUB] [W/m] is dielectric loss of cable insulation, T1, T2, T3 [K.m/W] are equivalent thermal resistances calculated from the cable material’s thermal properties, T4 [K.m/W] is the cable external thermal resistance, R[SUB]ac[/SUB] [Ω/m] is the AC electrical resistance of the cable conductor at maximum temperature and λ1 and λ2 are the ratio of losses in the metal sheath to total losses in all conductors and the ratio of losses in the armouring to total losses in all conductors, respectively.
Click to expand...
Not sure I can see that formula catching on TBH :)
 
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Is this for the cabins you were making which were intended for UK use? If so, wouldn't it be better to use standard UK wiring types? Daz
 
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Richard Burns said:
I would agree with the above posts about cable sizing too many variable in standards compliance and cable design.

However this webpage seems to discuss the methods used in IEC60287. I feel it is not worth working it out when the standard cables have been calculated (probably well on the side of caution!) for you.

Edit just found this
IEC METHOD
IEC 60287 provides method for calculation of current carrying capacity of cable for different design parameters of cable (cross section, thermal resistivity, thickness of layer … etc.) as well as for different environment (ambient temperature, soil condition, depth of cable, spacing of phases … etc.).The current rating (ampere) using in the IEC standard is:

View attachment 29359
where Δθ [[SUP]o[/SUP] C] is temperature rise between ambient temperature and cable conductor temperature, W[SUB]d[/SUB] [W/m] is dielectric loss of cable insulation, T1, T2, T3 [K.m/W] are equivalent thermal resistances calculated from the cable material’s thermal properties, T4 [K.m/W] is the cable external thermal resistance, R[SUB]ac[/SUB] [Ω/m] is the AC electrical resistance of the cable conductor at maximum temperature and λ1 and λ2 are the ratio of losses in the metal sheath to total losses in all conductors and the ratio of losses in the armouring to total losses in all conductors, respectively.
Click to expand...

Or you could just just my super scientific graph :) (please dont!)

current.cableGraph.jpg
 
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darkwood said:
This is because its under different regulations and the cable standards are also manufactured to differing regulation too, we have our own BS standards we follow and the cable we buy is manufactured to either EU or BS requirements.
Click to expand...


I think the insulation might have something to do with it... My understanding is that typical PVC insulated wires used in the UK are made for 70*C operation, while the 2.08mm2 PVC seems to be made for 90*C operation hence the higher current allowance in other regs.
 
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Also to note here is that the cables may be required a derating factor if connected to equipment rated at 70c, through experience that is most switchgear etc out there.
 
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darkwood said:
Also to note here is that the cables may be required a derating factor if connected to equipment rated at 70c, through experience that is most switchgear etc out there.
Click to expand...


Would de-rating cable for equipment allow for higher current? Ie the cable temperature is lower at the equipment as apposed to in contact with thermal insulation?

It seems those CCC tables by the cable maker take into account all installation methods.
 
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Gardner said:
Would de-rating cable for equipment allow for higher current? Ie the cable temperature is lower at the equipment as apposed to in contact with thermal insulation?

It seems those CCC tables by the cable maker take into account all installation methods.
Click to expand...

When you have a 90c cable it has a higher current rating but if it connects to standard 70c rated equipment then you need to apply a derating factor to the cables CCC which will reduce the load it can handle. This is a point often overlooked.
 
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darkwood said:
When you have a 90c cable it has a higher current rating but if it connects to standard 70c rated equipment then you need to apply a derating factor to the cables CCC which will reduce the load it can handle. This is a point often overlooked.
Click to expand...


Good point. That is something overlooked.
 
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happyhippydad said:
Or you could just just my super scientific graph :) (please dont!)

View attachment 29361
Click to expand...

... hhd; is that really 'your' graph ... ? I seem to remember that it was posted in response to a thread that you started; possibly by a 'dearly beloved' and 'departed' friend! You may correct me if I am wrong. Funnily enough, if the conditions of installation and design of the cable were sufficiently 'similar' to a particular 'case' recorded in a table in BS 7671 then that is the approach that I would take ... so long as the organisation that you work for has plenty of professional indemnity insurance and you or your boss has a big pair of 'cahunas' then I imagine that there shouldn't be too much of a problem. Unless the proverbial hits the fan and someone from that infamously litigious society across 'the pond' takes you to court!
 
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GB.Kayak said:
... hhd; is that really 'your' graph ... ? I seem to remember that it was posted in response to a thread that you started; possibly by a 'dearly beloved' and 'departed' friend! You may correct me if I am wrong. Funnily enough, if the conditions of installation and design of the cable were sufficiently 'similar' to a particular 'case' recorded in a table in BS 7671 then that is the approach that I would take ... so long as the organisation that you work for has plenty of professional indemnity insurance and you or your boss has a big pair of 'cahunas' then I imagine that there shouldn't be too much of a problem. Unless the proverbial hits the fan and someone from that infamously litigious society across 'the pond' takes you to court!
Click to expand...

In that case GB consider yourself corrected :smile5:

http://www.electriciansforums.co.uk...lations/101420-lollipop-circuit-40a-rcbo.html see post 19.
 
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Cross sectional area current capacity
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