ampacity of 2.5mm wire

[jbolen]

What is the largest breaker that can be installed on 2.5 mm wire.

Art 240.4 restricts the size on #14 to 15 amp breaker even if THHN @ 90 C says it is rated at 25 in art 310.15

ampacity of 2.5mm wire

 

[Dennis Alwon]

I think that 2.5mm is slightly less than 10 awg however we have no guidance on that so I would think 20 amp is your limitation except for certain situations such as motors or a/c units

http://www.powerwerx.com/wiregauge.asp

 

[kwired]

Funny thing is in countries that use SI units for everything, the conductor size is in SI units which is primarily a base 10 system but their standard overcurrent devices are not base 10 type settings. They have 16 and 32 amp overcurrent devices - not sure if there is a standard rating in between those two. I would not be surprised if the 2.5 mm is considered a 32 amp conductor outside the NEC.

 

[Dennis Alwon]

Funny thing is in countries that use SI units for everything, the conductor size is in SI units which is primarily a base 10 system but their standard overcurrent devices are not base 10 type settings. They have 16 and 32 amp overcurrent devices - not sure if there is a standard rating in between those two. I would not be surprised if the 2.5 mm is considered a 32 amp conductor outside the NEC.

That is very possible but since the op stated 310.15 I assumed NEC. Not sure why he has 2.5 mm wire.

 

[Smart $]

While the NEC "tries" to go metric, it does not recognize metric sized wire. Technically, using metric-sized wire on a project under NEC purview is a violation.

 

[kwired]

That is very possible but since the op stated 310.15 I assumed NEC. Not sure why he has 2.5 mm wire.

Not sure why he has 2.5 mm wire either. If not also marked in AWG there is a good chance it is not a conductor type mentioned in 310.104 and is not a NEC recognized conductor anyway.

 

[petersonra]

Not sure why he has 2.5 mm wire either. If not also marked in AWG there is a good chance it is not a conductor type mentioned in 310.104 and is not a NEC recognized conductor anyway.

that would appear to me to be the correct answer.

I don't see anything inherently unsafe with using metric sized wire that is not to US or NEC standards, and selecting an appropriate OCPD based on the cross sectional area of the wire. However, just because it is not inherently unsafe to do so, does not make it a good idea, as there is nothing you can point to in any recognized standards that supports doing so.

 

[mgookin]

http://www.engineeringtoolbox.com/awg-wire-gauge-d_731.html

That's a AWG to mm conversion chart.

Looks like you're close to a 14AWG with 2.5MM^2 wire.