Current mismatch 5-15P / C13 power cords

[IceNorm]

Power cords with a NEMA 5-15P plug on one end and IEC C13 plug on the other a very common. In looking through specs I find that the 5-15P is rated at 15A while the C13 is rated at only 10A. I would think that the powers that be would not allow this as it could be potentially dangerous.

Is anyone aware of why this is allowed?

Thanks!

 

[jghrist]

There should never be a plug (male) on both ends; very dangerous. If you mean a plug on one end (male) and a receptacle on the other (female), then it depends on which is which. If the female end is rated 10A, then only 10A equipment can be connected and the 15A end is OK.

 

[IceNorm]

While the C13 looks like a plug, it is actually an "inline socket". Please see:

http://en.wikipedia.org/wiki/IEC_connector

I am sure that everyone has seen and used these power cords, there are millions of them around.

While it is easy to say, just don't plug such a cord into equipment that pulls more than 10A, this would be completely impractical as who would know from a glance what a given piece of equipment draws.

If might be that authorities do not control the cord because they reason that such a cord would plug into a C14 chassis plug and since this is restricted to not draw more than 10A, the C13 would not draw more than 10A.

 

[stevenal]

So a piece of equipment drawing 10 A or less (usually way less) is plugged into a 10 A socket on a cord of sufficient gage which is in turn plugged into a 15 A receptacle. No overload.

 

[IceNorm]

I think you are misunderstanding my question. Regulatory agencies (OSHA?, UL?) don't deal in practicalities, they deal in possibilities. Would they approve a cord with a 15A plug but where the wire was rated for say 10A? Maybe they do all the time, I don't know. Practically this may work just fine, but there is a weakest link problem.

Lets imagine I am a European who designs a server with a C14 plug that uses 120V/220V power supply. My server needs 1.5 KW to operate which on my 220V system translates to 7A. Now my customer moves the equipment to the US. They see the C14 plug and plug in a standard 5-15P/C13 power cord. Because we are now operating at 120V, the system draws 14A which exceeds the 10A rating of the C13 outlet. Note that the US plug, wire and circuit breaker are just fine as they are rated to carry 15A.

You could plug this same equipment into a 20A circuit and draw almost 20A through the C13 outlet.

I was just wondering if anyone had any knowledge of how the regulatory agencies handled this situation.

 

[waross]

I doubt that the piece of equipment you have just described would receive approval for North American use.
respectfully

 

[IceNorm]

I am guessing that what this means is that to insure that a piece of equipment with a C14 plug is certifiable for use worldwide you would need to insure that it drew no more than 10A @ 120V even though it could draw twice that in a 220V environment.

Similarly you would be restricted to 16A at 120V is using a C20 plug.

Interesting.

Thank you to all that responded.

 

[jghrist]

There should be no problem with the cord set. You can't plug any equipment into it that is rated more than 10A unless that equipment is misusing a C14 plug. Now that I know what a C13 connector is, it seems like every computer sold in North America comes with the cord set you describe - a standard NEMA plug and a standard computer socket. I suspect that if any regulatory agencies have a problem with this, they have had ample opportunity to address the issue.

 

[LionelHutz]

Look at the ratings of the other connector ratings further down that page you linked. Some are rated 1.5A but can plug into a 15A receptacle.

Here in North America you can buy light duty extension cords that will not handle 15A yet have the 15A plug and receptacle on the ends meaning they are easier to misapply and cause problems compared to the cord set you describe.

 

[IceNorm]

Again, in thinking about it, I assume the regulatory agencies point of control is the equipment or more specifically the chassis plug (ex: C14 in the C13/C14 pair). If the equipment cannot draw more than the rated current then the power cord that plugs into the equipment is automatically limited.

Your comment about light duty power cords not being rated to carry the 15A that the plugs allow raises other questions.

Why would regulatory agencies certify such cords? Are they not potential hazards?

Of course, light duty cords have the major advantage of being very flexible and easy to work with.

Perhaps UL approves such cords assuming that they are likely to be used in situations where drawing near the full 15A is very unlikely (operating power tools, lights and the like) and where overheating would be noticed. OSHA conversely bans power cords for other than temporary use in businesses because they might installed semi-permanently, carry higher currents and be installed in areas (under desks) where they might go unobserved. This is just a guess.