Fuse Size

[Piratepete]

Hi Guys.
What exactly is the 13Amp plug fuse protecting? Appliance or cable? I often come across 13 Amp fuses that are clearly original supply but should IMHO be 5 0r 3 Amp. Typically this occurs on Fridges and Vacuum Cleaners.So I change it acording to the running current (and considering starting current) but I wonder if the manufacturer knows something that I don't?
Cheers
Pete

 

[pete555]

Hi Guys.
What exactly is the 13Amp plug fuse protecting? Appliance or cable? I often come across 13 Amp fuses that are clearly original supply but should IMHO be 5 0r 3 Amp. Typically this occurs on Fridges and Vacuum Cleaners.So I change it acording to the running current (and considering starting current) but I wonder if the manufacturer knows something that I don't?
Cheers
Pete

the appliance the cable should already be rated to the appliance

 

[steviebeck]

The fuse in a plug is there to primarily protect the flex, but generally will protect the appliance also.

With fridges and and vacuum cleaners there will be higher than normal inrush currents and hence these items tend to have a higher rated fuse than normal.

 

[sparkless]

Vila Is Rubbish

 

[telectrix]

what's vila?

 

[wildgoose]

Generally fuses are fitted to protect the cable or cord from excessive current flow and subsequent thermal damage.

 

[Piratepete]

Generally fuses are fitted to protect the cable or cord from excessive current flow and subsequent thermal damage.

So if the manufacturer's fuse is 13 Amp and the cable is meaty enough do you leave it at that?

 

[Marvo]

Fuses, like MCB's protect the cable they supply from being damaged by over current. There are no fuses in plugtops where I am and I have mixed feelings about them because it's so easy to replace it with one that's incorrectly sized plus they're unlikely to blow unless the overload is severe such as a fault current (in which case the circuit is already protected in the DB or CU) but they're very sloppy when it comes to marginal overload such as too may items plugged into an extension lead.

If the manufacturer supplied the appliance with a 13A plug fuse then you should stick with that rating unless there's an obvious reason not to.

 

[oldtimer]

Yep I have lost count following a "professional" PAT testers who never bothered to check the fuses with me changing 13A to 3A fuses

 

[ohreally]

I regularly encounter manufacturer fitted supply cords .50/.75 fitted with 13A fuses. Piezzo igniter in hobs being an example.

3rd ed cop...

15.14 (page 82 2nd para) Quote:

The fuse in the plug is not fitted to protect the appliance...the fuse in the plug protects the flex against fault and can allow the use of a reduced csa flexible cable.

Quote:

if the appliance needs a fuse to comply with its manufacturing standard, it should be fitted in the appliance

 

[SirKit Breaker]

The plug fuse is there to protect the appliance flex, but the good book does say, appliances up to 700w 3a fuse, 700w and upwards 13a fuse, in any event, the fuse stated by the manufacturer should be fitted where that is known.

Cheers...........Howard

PS the good book is the COP for in service insp and test of electrical equipment.

 

[steviebeck]

I regularly encounter manufacturer fitted supply cords .50/.75 fitted with 13A fuses. Piezzo igniter in hobs being an example.

3rd ed cop...

15.14 (page 82 2nd para) Quote:

The fuse in the plug is not fitted to protect the appliance...the fuse in the plug protects the flex against fault and can allow the use of a reduced csa flexible cable.

Quote:

if the appliance needs a fuse to comply with its manufacturing standard, it should be fitted in the appliance

In the case above a manufacturer flex of 0.75 should have a moulded plug fitted and should have a length under 2M and this is allowed to be fused at 13A under BS1363