Voltage and Current rating of computer power cable

tpetar · Mar 17, 2012

I say what can be happen. Also if you read my previous posts, ...

FvM · Mar 17, 2012

I hear some misunderstandings.

- cable voltage rating hasn't to do with "wire melting".
- voltage rating printed on the cable is a special requirement of some UL and CSA standards, if I remember right. The respective cable "style" number should be printed along with the rating.
- the same cable can possibly comply with CE or other international standards for higher voltages (e.g. 300 V working voltage)
- voltage and current ratings of the connector are printed on the connector

kevindd992002 · Mar 17, 2012

FvM said:
I hear some misunderstandings.

- cable voltage rating hasn't to do with "wire melting".
- voltage rating printed on the cable is a special requirement of some UL and CSA standards, if I remember right. The respective cable "style" number should be printed along with the rating.
- the same cable can possibly comply with CE or other international standards for higher voltages (e.g. 300 V working voltage)
- voltage and current ratings of the connector are printed on the connector

@tpetar

This is exactly what I was trying to point out. Voltage rating is simply there as a way of indicating "form factor" of the connector and is not to be treated as electrical rating.

tpetar · Mar 17, 2012

I say connector melting is possible not wire or cable melting.

That voltage mark on connector is not just some mark on connector. You should use adequate power cable with adequate connector for your needs. If you read my previous posts I say that power cable can be used and nothing special will happen, but who knows...

I have somewhere some pdf of some manufacturer where they say what can be happen when use 110V 60Hz power cable on 220V 50Hz system. If I find that pdf I will post here.

About form factor of the AC current is the average value by rms value.

FvM · Mar 17, 2012

I say connector melting is possible not wire or cable melting.

With the term "wire melting", I was referring to a post from kevindd992002. "Connector melting" as a result of exceeded voltage ratings sounds equally unlikely, by the way. You'll rather relate both to overcurrent.

kevindd992002 · Mar 17, 2012

FvM said:
With the term "wire melting", I was referring to a post from kevindd992002. "Connector melting" as a result of exceeded voltage ratings sounds equally unlikely, by the way. You'll rather relate both to overcurrent.

Well, I got the term "wire melting" from a post from tpetar, in turn. Correct, metling, whether the wire or connector, can be caused by overcurrent and not overvoltage. Voltage is simply a "force" for the current flow. Wires (conductors) usually have current and temperature ratings which are causes of fire or melting.

You can even plug a 110V rated electric fan blower into a 220V outlet and what fires up? The fan head itself not the wire. I don't know if that makes sense or is connected with this topic though.

Syncopator · Mar 17, 2012

jeet_asic said:
The voltage rating will specify how much electrical current can safely be carried through the wiring, ...

Then, logically, the corollary must be that the current rating will specify how much electrical voltage the wiring can withstand.

kevindd992002 · Mar 17, 2012

Syncopator said:
Then, logically, the corollary must be that the current rating will specify how much electrical voltage the wiring can withstand.

In that case, we can use the formula for Power then, W=V x I. If the cable is rated at 115V 10A, that is a total of 1.15KW. So using that same cable with a 230V outlet, you should limit current draw to 5A in order not to exceed 1.15KW. But this is not the case for wires because these are simply conductors and do not have any power rating. This was my original question so I'm not sure if I missed some important points to be discussed with this one.

tpetar · Mar 17, 2012

Dear Kevin,

Well, I got the term "wire melting" from a post from tpetar, in turn. Correct, metling, whether the wire or connector, can be caused by overcurrent and not overvoltage. Voltage is simply a "force" for the current flow. Wires (conductors) usually have current and temperature ratings which are causes of fire or melting.

You can even plug a 110V rated electric fan blower into a 220V outlet and what fires up? The fan head itself not the wire. I don't know if that makes sense or is connected with this topic though.

I dont see your point what you whant to ask or to do ? Can You find my post where I say wire melting? (not metling like you say). Read carefully posts of other users.

What to say after this :shock: :

You can even plug a 110V rated electric fan blower into a 220V outlet and what fires up? The fan head itself not the wire.

8-O

Original Kevin question is:

The power cable that came with the Autovolt power supply of my computer is rated 125V 10A. My computer is directly connected to a 230V outlet. Now, why do these power cables have a Voltage rating? I know that the Current rating is important but why the voltage?

in Kevin post 28 he say :

In that case, we can use the formula for Power then, W=V x I. If the cable is rated at 115V 10A, that is a total of 1.15KW. So using that same cable with a 230V outlet, you should limit current draw to 5A in order not to exceed 1.15KW. But this is not the case for wires because these are simply conductors and do not have any power rating. This was my original question so I'm not sure if I missed some important points to be discussed with this one.

I dont understand what Kevin whant to aks?

In post 27 you get nice answer.

Syncopator · Mar 17, 2012

tpetar said:
In post 27 you get nice answer.

I was trying to point out that the correspondent seemed to be confused between voltage and current .....

kevindd992002 · Mar 17, 2012

tpetar said:
Dear Kevin,

I dont see your point what you whant to ask or to do ? Can You find my post where I say wire melting? (not metling like you say). Read carefully posts of other users.

What to say after this :shock: : 8-O

Original Kevin question is:

in Kevin post 28 he say :

I dont understand what Kevin whant to aks?

In post 27 you get nice answer.

Sorry about that. All I was trying to say is that voltage rating seems not to correspond to melting with power cables.

tpetar · Mar 17, 2012

All I was trying to say is that voltage rating seems not to correspond to melting with power cables.

Ok, but nobody said such thing in posts. But you should know that all power cables should have current capacity (related to square area of conductor), power ratings (related to current and defined voltage), working temp, voltage insulation breakdown test certificate,...

My opinion for your problem is (again), to get appropriate power cable for your electric mains system 110V/220V. Power cable should have voltage mark 220V for 220V, or 110V for 110V systems, or can be 110/220 mark, or some other marks like for three phase 400V 600V. Also use appropriate connector for your female wall electric connector.

If You interested for differences in 110V 60Hz and 220V 50Hz start new thread.

kevindd992002 · Mar 17, 2012

tpetar said:
Ok, but nobody said such thing in posts.

My opinion for your problem is (again), to get appropriate power cable for your electric mains system 110V/220V. Power cable should have voltage mark 220V for 220V, or 110V for 110V systems, or can be 110/220 mark. Also use appropriate connector for your female wall electric connector.

If You interested for differences in 110V 60Hz and 220V 50Hz start new thread.

Again, sorry, I must've misread "connector" for "wire" melting.

tpetar · Mar 17, 2012

No problem for that, I understand.

If I find pdf I will post it. PDF is about connectors for 110V and 220V and what happen with 110V 60Hz connector on 220V 50Hz and reverse with picture like examples.

kevindd992002 · Mar 17, 2012

tpetar said:
No problem for that, I understand.

If I find pdf I will post it. PDF is about connectors for 110V and 220V and what happen with 110V 60Hz connector on 220V 50Hz and reverse with picture like examples.

Ok thanks.

Now this is weird. I found another cable laying around in my house here. The FEMALE connector is 125V 10A rated (this rating is the one I was referring to the whole time) but the markings on the cable itself says "(UL) E157674-SZ SVT VW-1 75°c 300v 3X18AWG10.824mm^2) LL101980". What is that?

tpetar · Mar 17, 2012

SVT mark say that that cable is for is commonly used small tools and appliances such as vacuum cleaners, food processors, and office equipment. SJT mark is designed for use with heavy tools, equipment, portable lights, and power extensions.

Depending on the type of insulating material, common maximum allowable temperatures at the surface of the conductor are 60, 75, and 90 °C, often with an ambient air temperature of 30 °C.

Can be safely used for 300V configuration. Its monophase cable.

18 AWG (American Wire Gauge) is 1,02mm diameter of wire and 0,82mm2 cross sectional area, or standardized cable 0,75mm2. That cable is for up to 500W on 220V system.
18 AWG is for max 2,3A power transmission and max freq 17KHz 100% skin effect.

Additional material :
https://en.wikipedia.org/wiki/Ampacity
https://www.powerstream.com/Wire_Size.htm
https://diyaudioprojects.com/Technical/American-Wire-Gauge/
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

Additional brainstorming for Kevin :
Read about skin effects
Why used stranded wire and why full cross-section in AC and DC systems.
How current flows throught cable based on frequency.

;-)

kevindd992002 · Mar 17, 2012

tpetar said:
SVT mark say that that cable is for is commonly used small tools and appliances such as vacuum cleaners, food processors, and office equipment. SJT mark is designed for use with heavy tools, equipment, portable lights, and power extensions.

Depending on the type of insulating material, common maximum allowable temperatures at the surface of the conductor are 60, 75, and 90 °C, often with an ambient air temperature of 30 °C.

Can be safely used for 300V configuration. Its monophase cable.

18 AWG (American Wire Gauge) is 1,02mm diameter of wire and 0,82mm2 cross sectional area, or standardized cable 0,75mm2. That cable is for up to 500W on 220V system.
18 AWG is for max 2,3A power transmission and max freq 17KHz 100% skin effect.

Additional material :
https://en.wikipedia.org/wiki/Ampacity
https://www.powerstream.com/Wire_Size.htm
https://diyaudioprojects.com/Technical/American-Wire-Gauge/
https://en.wikipedia.org/wiki/AC_power_plugs_and_sockets

Additional brainstorming for Kevin :
Read about skin effects
Why used stranded wire and why full cross-section in AC and DC systems.
How current flows throught cable based on frequency.

;-)

So why is the connector rated 10A then?

I kinda know skin effect cause I'm a licensed Electronics Engineer here in the Philippines

Graduated as an Electronics Engineer.

tpetar · Mar 17, 2012

Connector is for 125V 10A !!!! Connector can handle up to 10A.

Cable is how you say : "(UL) E157674-SZ SVT VW-1 75°c 300v 3X18AWG10.824mm^2) LL101980" its for up to 2,3A current load.

Dont mix connector markings with cable markings.

Connector is often manufactured as 10A and 16A ratings.

If You are

I kinda know skin effect cause I'm a licensed Electronics Engineer here in the Philippines Graduated as an Electronics Engineer.

You have all of this in small finger and you already knows that, sorry.

kevindd992002 · Mar 17, 2012

tpetar said:
Connector is for 125V 10A !!!! Connector can handle up to 10A.

Cable is how you say : "(UL) E157674-SZ SVT VW-1 75°c 300v 3X18AWG10.824mm^2) LL101980" its for up to 2,3A current load.

Dont mix connector markings with cable markings.

Connector is often manufactured as 10A and 16A ratings.

If You are
You have all of this in small finger.

Yes, yes, I understand you completely!

What I don't understand is why will one put a 10A rated connector on a 2.3A rated cable. It just doesn't make any sense.

tpetar · Mar 17, 2012

Because, I try to say something in some previous post about melting of connector but story goes on other way, point of power contacts are often problematic and cause of fire and other problems if badly instaled or used. Manufacture of electrics material make standardized things, such is power plug connectors. They make 10A and 16A, also there is others power connectors for 25A.

Weakest link in power cable is power connector if there is no overload of complete cable and ambient temp is in allowed range!!!.

Power connector is in touch with hand while plugin in into wall mains connector, connector must be safe.
In my post #36 I give You link about power connectors.

I have one question for you. What is designed power of your PC power supply ?

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