Ampacity of a computer/printer power supply cord

[Codified]

I'm trying to determine precisely what the "allowable" ampacity is for a computer/printer power supply cord. It's 6-feet long, 300V, Type SJT, 18 AWG, 60/75C rated (these typically have an IEC 60320, C13 connector at one end, for plugging into the back of a printer of desktop PC). Nowhere on the cord or connector is the rated ampacity stated (many similar cords say 10A). I have looked through the NEC (e.g., Articles 310 & 400), but am not sure how (or if) the NEC applies to it. It is in an ambient temperature greater than 30C, but less than 60C, so I'm thinking that temperature correction factors would apply.

So, how would one assess its ampacity?

 

[iwire]

The NEC has a absolutely nothing to do with it.

The cord will be rated for whatever the C13 receptacle on it is rated for.

 

[Codified]

Thanks for the quick answer at this late hour, iwire. Unfortunately, the info on the C13 connector is a bit scant - it does not state a current rating. I have no reason to doubt or disagree with your answer, but I need to document a basis for whatever determination I ultimately make.

Can you point to a source, such as a standard, or similar, that would back it up? UL 62?

 

[iwire]

10 amps.


https://www.google.com/#q=current+rating+c13&safe=off

 

[Dennis Alwon]

If the cord is computer equipment I don't see where the nec has anything to say about it.

 

[fmtjfw]

NEC is not silent

NEC is not silent

I'm trying to determine precisely what the "allowable" ampacity is for a computer/printer power supply cord. It's 6-feet long, 300V, Type SJT, 18 AWG, 60/75C rated (these typically have an IEC 60320, C13 connector at one end, for plugging into the back of a printer of desktop PC). Nowhere on the cord or connector is the rated ampacity stated (many similar cords say 10A). I have looked through the NEC (e.g., Articles 310 & 400), but am not sure how (or if) the NEC applies to it. It is in an ambient temperature greater than 30C, but less than 60C, so I'm thinking that temperature correction factors would apply.

So, how would one assess its ampacity?

One would look at the standards or extracts of same. Goggle "IEC C13"

IEC 60320-1

C13 = 10A

http://en.wikipedia.org/wiki/IEC_60320#Standards

And see NEC Table 400.5(A)(1) for #18 SJT under column B (for two CCC) and also find 10A

 

[iwire]

And see NEC Table 400.5(A)(1) for #18 SJT under column B (for two CCC) and also find 10A

And again the NEC ampacity tables have no more to do with this than Santa has to do with 4th of July.

 

[mgookin]

Thanks for the quick answer at this late hour, iwire. Unfortunately, the info on the C13 connector is a bit scant - it does not state a current rating. I have no reason to doubt or disagree with your answer, but I need to document a basis for whatever determination I ultimately make.

Can you point to a source, such as a standard, or similar, that would back it up? UL 62?

UL62 seems appropriate.

 

[fmtjfw]

It is Christmas in July

It is Christmas in July

And again the NEC ampacity tables have no more to do with this than Santa has to do with 4th of July.

First:
The OP asked for the ampacity of SJT #18 and C13. NEC has a table of ampacities for cords.

Second:
400.7 Uses Permitted.
(A) Uses. Flexible cords and cables shall be used only for
the following:
(1) Pendants.
(2) Wiring of luminaires.
(3) Connection of portable luminaires, portable and mobile
signs, or appliances.
(4) Elevator cables.
(5) Wiring of cranes and hoists.
(6) Connection of utilization equipment to facilitate frequent
interchange.
(7) Prevention of the transmission of noise or vibration.
(8) Appliances where the fastening means and mechanical
connections are specifically designed to permit
ready removal for maintenance and repair, and the
appliance is intended or identified for flexible cord
connection.
(9) Connection of moving parts.
(10) Where specifically permitted elsewhere in this Code.
(11) Between an existing receptacle outlet and an inlet,
where the inlet provides power to an additional single
receptacle outlet. The wiring interconnecting the inlet
to the single receptacle outlet shall be a Chapter 3
wiring method. The inlet, receptacle outlet, and Chapter
3 wiring method, including the flexible cord and
fittings, shall be a listed assembly specific for this
application.
(B) Attachment Plugs. Where used as permitted in
400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be
equipped with an attachment plug and shall be energized
from a receptacle outlet or cord connector body.

Appliance is undefined in NEC

Dictionary Definition --

appliance noun 1. a device or piece of equipment designed to perform a specific task, typically a domestic one.

Computer perform computation, a specific task.

 

[PetrosA]

Every IEC cord I've ever seen has markings on it like this.

 

[kwired]

First:
The OP asked for the ampacity of SJT #18 and C13. NEC has a table of ampacities for cords.

Second:
400.7 Uses Permitted.
(A) Uses. Flexible cords and cables shall be used only for
the following:
(1) Pendants.
(2) Wiring of luminaires.
(3) Connection of portable luminaires, portable and mobile
signs, or appliances.
(4) Elevator cables.
(5) Wiring of cranes and hoists.
(6) Connection of utilization equipment to facilitate frequent
interchange.
(7) Prevention of the transmission of noise or vibration.
(8) Appliances where the fastening means and mechanical
connections are specifically designed to permit
ready removal for maintenance and repair, and the
appliance is intended or identified for flexible cord
connection.
(9) Connection of moving parts.
(10) Where specifically permitted elsewhere in this Code.
(11) Between an existing receptacle outlet and an inlet,
where the inlet provides power to an additional single
receptacle outlet. The wiring interconnecting the inlet
to the single receptacle outlet shall be a Chapter 3
wiring method. The inlet, receptacle outlet, and Chapter
3 wiring method, including the flexible cord and
fittings, shall be a listed assembly specific for this
application.
(B) Attachment Plugs. Where used as permitted in
400.7(A)(3), (A)(6), and (A)(8), each flexible cord shall be
equipped with an attachment plug and shall be energized
from a receptacle outlet or cord connector body.

Appliance is undefined in NEC

Dictionary Definition --

appliance noun 1. a device or piece of equipment designed to perform a specific task, typically a domestic one.

Computer perform computation, a specific task.

In general though the NEC usually ends at the outlet not at the computer in such an instance. That cord may have an ampacity value but it is not necessarily determined by NEC. It is a listed component or accessory of a listed assembly.

 

[petersonra]

I'm trying to determine precisely what the "allowable" ampacity is for a computer/printer power supply cord. It's 6-feet long, 300V, Type SJT, 18 AWG, 60/75C rated (these typically have an IEC 60320, C13 connector at one end, for plugging into the back of a printer of desktop PC). Nowhere on the cord or connector is the rated ampacity stated (many similar cords say 10A). I have looked through the NEC (e.g., Articles 310 & 400), but am not sure how (or if) the NEC applies to it. It is in an ambient temperature greater than 30C, but less than 60C, so I'm thinking that temperature correction factors would apply.

So, how would one assess its ampacity?

you would not need to assess its ampacity, so why waste your time trying to do so? UL has already made the assessment. stuff like this cannot be "assessed" based on anything to be found in the NEC. It is utilization equipment and thus for the most part not covered by the NEC at all.

 

[fmtjfw]

WELCOME to the Board.

WELCOME to the Board.

I'm trying to determine precisely what the "allowable" ampacity is for a computer/printer power supply cord. It's 6-feet long, 300V, Type SJT, 18 AWG, 60/75C rated (these typically have an IEC 60320, C13 connector at one end, for plugging into the back of a printer of desktop PC). Nowhere on the cord or connector is the rated ampacity stated (many similar cords say 10A). I have looked through the NEC (e.g., Articles 310 & 400), but am not sure how (or if) the NEC applies to it. It is in an ambient temperature greater than 30C, but less than 60C, so I'm thinking that temperature correction factors would apply.

So, how would one assess its ampacity?

I hope your question has been answered.

Pay no attention to the tussle.

 

[fmtjfw]

Why such a big deal?

Why such a big deal?

I'm trying to determine precisely what the "allowable" ampacity is for a computer/printer power supply cord. It's 6-feet long, 300V, Type SJT, 18 AWG, 60/75C rated (these typically have an IEC 60320, C13 connector at one end, for plugging into the back of a printer of desktop PC). Nowhere on the cord or connector is the rated ampacity stated (many similar cords say 10A). I have looked through the NEC (e.g., Articles 310 & 400), but am not sure how (or if) the NEC applies to it. It is in an ambient temperature greater than 30C, but less than 60C, so I'm thinking that temperature correction factors would apply.

So, how would one assess its ampacity?

OK, so this new guy comes to the forum and asks:

What is the allowable ampacity for SJT AWG 18 with C13 connector.

He says the cord doesn't have it imprinted on on.

He says he's not sure NEC applies.

He also wants to know if a temperature of between 30?C and 60?C would reduce it.

These answers to these two questions about ampacity are found on the web and in NEC 400.

Some suggest that this is not covered by NEC, maybe, maybe not. But a really good answer to the ampacity of #18 SJT is available in the NEC.

Now someone suggests looking at UL62. -- cost $95 for the 1991 version on Amazon. I'd bet that the table in NEC 400 resembles the info in UL62, and can be viewed for free on the NFPA.org site.

Someone else thinks this is a question for UL. -- here he is talking about a plug and cord set, maybe he plans to cut off the C13 and wants to know how many 100W bulbs he can wire in parallel without overheating the cord?

Maybe he accidentally cut his current IEC cord and wants to know if another one on hand can substitute?

 

[Codified]

I hope your question has been answered.

All the input helps and is appreciated (even Bob's) - I want to consider all avenues to getting the "right determination" for the installations of the cords-in-question. The bigger question is whether these 18 AWG, SJT cords (with C-13 connectors) are appropriate for 10A in ambient temperatures of about 40C (104 F).

It does seem that C13 connectors are generally rated 10A, and that the NEC is not applicable for the particular 'cord-with-C13-connector' applications/installations. Nevertheless, it intrigues me that the NEC's 400.5 does not require temperature correction for the First table (only the 2nd table). Fyi, here is an excerpt from 400.5(A) of the 2011 NEC:
"Where cords are used in ambient temperatures other than 30?C (86?F), the temperature correction factors from Table 310.15(B)(2)(a) that correspond to the temperature rating of the cord shall be applied to the ampacity in Table 400.5(A)(2)."

UL 62, IEC 60320-1 & -2 may hold the specific answers/info, but that path can be a bit encumbering & expensive. If I must go that route, I will, but I'm hoping for a more direct path to the answer. Once again, the main issue is applicability of the cord & connector with consideration of high ambient.

 

[Smart $]

... Nevertheless, it intrigues me that the NEC's 400.5 does not require temperature correction for the First table (only the 2nd table). Fyi, here is an excerpt from 400.5(A) of the 2011 NEC:
"Where cords are used in ambient temperatures other than 30?C (86?F), the temperature correction factors from Table 310.15(B)(2)(a) that correspond to the temperature rating of the cord shall be applied to the ampacity in Table 400.5(A)(2)."

...

FWIW, not mentioning Table 400.5(A)(1) appears to be an oversight corrected in 2014. Same sentence in 2014:
"Where cords and cables are used in ambient temperatures other than 30?C (86?F), the temperature correction factors from Table 310.15(B)(2)(a) that correspond to the temperature rating of the cord or cable shall be applied to the ampacity in Table 400.5(A)(1) and Table 400.5(A)(2)."

 

[Codified]

FWIW, not mentioning Table 400.5(A)(1) appears to be an oversight corrected in 2014. Same sentence in 2014:
"Where cords and cables are used in ambient temperatures other than 30?C (86?F), the temperature correction factors from Table 310.15(B)(2)(a) that correspond to the temperature rating of the cord or cable shall be applied to the ampacity in Table 400.5(A)(1) and Table 400.5(A)(2)."

I don't yet have the 2014 edition, so thank you for the update. I checked the previous 7 cycles, going back to 1993, and none included temperature correction for the first table of 400.5. Temperature correction for the 2nd table started only with the 2005 NEC.

 

[fmtjfw]

UL 62

UL 62

It's about construction details. Does not appear to contain ampacities.

 

[jtinge]

NFPA 79-Industrial Machinery has the following on cords:

12.8 Cords.
12.8.1 Cords shall be suitable for the intended use and be of
the type listed in Table 12.8.2. Other cords of the types identified
in NFPA 70, Table 400.4 that are part of a listed assembly
and are suitable for the intended use shall be permitted.
Exception: Other cord types shall be permitted where part of a listed
assembly or otherwise identified as suitable for the intended application.
12.8.2* Ampacity of Cords. The continuous current by cords
shall not exceed the values given in Table 12.8.2.
12.8.3 Where ampacity derating is required for more than
three current-carrying conductors, the factor(s) shall be taken
from Table 12.5.5(b).

Table 12.8.2 Allowable Ampacity for Cords [Based on
Ambient Temperature of 30?C (86?F)] lists the ampacity of 18 AWG as 7 amps
for the * note below, and 10 amps for the ? note below.

*The allowable currents apply to 3-conductor cords and other multiconductor
cords connected to utilization equipment so that only 3
conductors are current carrying.

? The allowable currents apply to 2-conductor cords and other multiconductor
cords connected to utilization equipment so that only 2
conductors are current carrying.

An explanatory note indicates that the ampacity values in Table 12.8.2 are based on Table 400.5(5) of NFPA 70.

 

[SceneryDriver]

All the input helps and is appreciated (even Bob's) - I want to consider all avenues to getting the "right determination" for the installations of the cords-in-question. The bigger question is whether these 18 AWG, SJT cords (with C-13 connectors) are appropriate for 10A in ambient temperatures of about 40C (104 F).

It does seem that C13 connectors are generally rated 10A, and that the NEC is not applicable for the particular 'cord-with-C13-connector' applications/installations. Nevertheless, it intrigues me that the NEC's 400.5 does not require temperature correction for the First table (only the 2nd table). Fyi, here is an excerpt from 400.5(A) of the 2011 NEC:
"Where cords are used in ambient temperatures other than 30?C (86?F), the temperature correction factors from Table 310.15(B)(2)(a) that correspond to the temperature rating of the cord shall be applied to the ampacity in Table 400.5(A)(2)."

UL 62, IEC 60320-1 & -2 may hold the specific answers/info, but that path can be a bit encumbering & expensive. If I must go that route, I will, but I'm hoping for a more direct path to the answer. Once again, the main issue is applicability of the cord & connector with consideration of high ambient.

Not to be pedantic, as that's not my intention, but if there's a question as to the ampacity at a given temperature for 18ga cord, why can't you simply replace it with a heavier gauge? I have in my shop a goodly collection of C13 power cords with wire gauges ranging from 18ga to 14ga. It's amazing what I can get from out IT department just for the asking. They're a common, easy to replace item. If there's question regarding the 18ga cords, can you not simply replace them with something heavier? Amazon sells them by the truckload for cheap.

For instance:
http://www.amazon.com/SF-Cable-Univ...d_sim_e_3?ie=UTF8&refRID=0MBSM9ZETRR84DBD30BS


-SceneryDriver