which amp fuses please?

  Effie 23:48 30 Jan 05

Hi, does anyone know what amp fuse you should be using with computers and monitors?

Currently I have a monitor whose power lead has a 13 amp fuse on it but which uses only 120 watts of electricity. The computer on the other hand consumes 350 watts and has a 5 amp fuse on its power lead.

Both of them are currently running through an extension block which has a 13 amp fuse on it.

ideas anyone??

  thms 12:01 31 Jan 05

If I remember correctly Power=AmpsxVoltage.
Therefore Power/Volatge=Amps

  Newuser4165 12:27 31 Jan 05

The fuse is designed to protect the wiring of an appliance - not the appliance itself.
In modern wiring you should be able to read the max current for the power lead either on the lead itself or on the plug eg 5A in the case of the pc power lead.
Similarly the power lead for the monitor may be rated at 13A as it can handle a total load of 13A but it may be worthwhile checking that this is the case.
In the case of the extension lead then you need to be more careful and ensure that the total load on the extension cable does not exceed 13A which is very easy to do if you connected for example an electric kettle,dishwasher,washing machine and ran them all at the same time.In your case there isn't a problem.

The current carrying capacity of a cable is related to the cross-sectional area of the copper core .Typically 1sq.mm can carry 5amps , 2.5sq.mm can carry 13 amps although there can be some latitude in this but I won't go into it here.

  Squib 15:51 31 Jan 05

Fuses are said to be selected to protect the lead from plug to appliance, as set out before, but it might save the appliance if you rate the fuse to demand.
Roughly 1000watts is 4amps [called a kw or kilowatt]. The 13A fuse caters for 3kw, which is a large electric fire full on.The fuse must be big enough not to overheat when appiance is full on. The rating plate, as you have seen, gives demand in amps or kw.
Working on 4A per kw plus a little bit, it should be fairly easy to work out a fuse size, as they come in these sizes for household general use = 1A, 3A, 5A, 7A, 10A and 13A.You will only find two or three sizes in general shops..try Maplins,R.Dyas. O.K.?

  Stuartli 16:16 31 Jan 05

..this link will amaze and shock (no pun intended) you:

click here

Apparently, for the convenience of users, portable appliance manufacturers have standardised on two plug fuse ratings- 3A & 13A and adopted appropriate flex sizes.

For appliances up to 700W a 3A fuse is used, for those over 700W a 13A fuse is used (click here).

RoSPA's website (click here) states:

Appliances up to 720 watts: 3 Amp fuse

From 720 to 1200 watts: 5 Amp fuse

From 1200 to 3000 watts: 13 Amp fuse

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