Plugs and Fuses - Help understanding symbols (PC/Monitor)

Barney1234 · Mar 4, 2024

I have a question which is confusing me and I cannot find a definitive answer and I hope someone can help.
So I have a PC and Monitor and I have misplaced the IEC cables in a house move.(Somewhere in a box labelled cables hopefully)
My question is I have found this spare on one a box. (see pics)
Looking at the symbols on the plug (as looking at the 3 pins in the photos) there is a 5/250 numbers next to the right pin.
What does this mean?
Does it mean the fuse that should (or must) be used is a 5amp fuse?
Can I place a 10amp, 13amp or 3amp fuse in this plug?
Looking at the other end on the photo there is then another 10A / 250 V
What does this mean? Why does it have 2 ratings and which do I go for??

This is to be used in a monitor Benq GW2255 which looking at the ratings and specification it is using power consumption 28W.... so

P (Watts) ÷ V (Voltage) = I (Amps)
28 / 240 = 0.1166666666666667 amps

0.11 amps

This would mean a 3amp fuse..... correct??

So looking at the photograph of the plug, can I use this in the monitor if I take out the existing fuse (which is 5amp currently and replace with a 3amp fuse?) or shall I used a plug that has the rating 3/240 on it?

I am confused as to why the cable as the 5/250 rating ( I presume 5 amps / 250 (240V))

Also I have found another IEC cable that is longer than 6ft but has the 13/240 symbol on. Due to the location of the plug and monitor I did want to use this longer cable for the monitor but saw that the cable has 13/240 so didn't want to assume I can take the 13amp fuse out and put in a 3amp fuse for the monitor.

The PC is using a 5amp fuse which I hope is correct?

Can anyone put my mind at rest and answer the questions above and why each end has difference ratings?

westward10 · Mar 4, 2024

The 250 is the voltage, 5 the current rating so fit no more than a 5A fuse. This 5A is not the rating of the plug but the cable moulded to it.
The other end is rated at 10A.

Barney1234 · Mar 5, 2024

westward10 said:
The 250 is the voltage, 5 the current rating so fit no more than a 5A fuse. This 5A is not the rating of the plug but the cable moulded to it.
The other end is rated at 10A.

Hi Westward10

Many thanks for the reply. Just a couple of questions for clarification (and piece of mind)

1) So in that image of the plug where it says 5A/240 you are saying a 5amp fuse (or less) can be fitted into that plug?
2) I have since found another cable but it has 13/240 on it. It has a 13amp fuse in.... Can I take this out and replace with a 5amp fuse and use that in the monitor instead (or PC)??
3) Can I use a longer IEC cable with a 13amp fuse in and plug that into the monitor?
4) What do you mean by the other end is rated at 10Amp? So does that mean I can't plug this into a monitor or PC?? I cant understand why one end is 5amp and the other 10amp.... does that mean all plugs are shown like this?
5) Is there a online calculation tool I can use to work out the fuse to use in a plug?

It's the confusing factor of the device (Monitor) is using 0.11 amps so would I use a 3amp fuse in the cable for the monitor.... but the plug I have is showing 13/240??

Just to confirm is this correct:

P (Watts) ÷ V (Voltage) = I (Amps)
28 / 240 = 0.1166666666666667 amps

0.11 amps

I am now reading that PC's / monitors are using 5amp fuses in IEC leads.... but that is more than a 3amp fuse if going on the calculation above. I just need piece of mind that what I am using is OK and safe and that different fuses can go into different plugs.

Thanks again.

westward10 · Mar 5, 2024

1. Yes 5A or less.
2. Yes assuming the socket fits the monitor.
3. Yes but the monitor will not require a 13A fuse.
4. The 10A end fits into the monitor. 10A is it's maximum rating but the monitor will never achieve a 10A draw so ignore that.
5. Your calculation is fundamentally correct.
You could fit 3A fuses but the start-up current may blow it hence 5A fuses are generally used, the fuse is there to protect the cable. You may be able to see the cable size on the cable sheath like 3×0.75 or 3×1.0.
0.75 is rated at 7A and 1.0 rated at 10A so a 5A fuse is fine in both cases.

littlespark · Mar 5, 2024

The same socket can be used for different appliances, such as kettles... which will draw more than 5A

The size of the cable determines how much current can go through it... 5A, smaller cabler... 10A, larger cable.... They just put the same socket on the end of different sizes of cable

The fuse should be sized to protect the cable, not the appliance on the end.... So, dont take a cable designed for 5A, with a 5A fuse... change to a 13A fuse and plug it into a kettle.

The same type of socket is used for monitors, desktop PC's and laptop adaptors....So they are pretty generic.
A high end gaming PC may need a higher rated cable than a small monitor.... but a 5A fuse in any EIC lead will be fine for IT devices