plug top fuses - what is the point?

[Steve]

I got to work this morning at 5am. Went upstairs and put kettle on. BANG. kettle, CCTV, everything on upstairs ring, went off. Turns out that somehow the kettle base was covered in water. So i went down the cellar and flipped the MCB back on. The plug fuse must have blown, since i realised it was still plugged in when i went back upstairs, and still sopping wet. At this point, i realise water is all o'er t'floor and worktop - the kettle must have been leaking.

The thing is, if a 32A type B MCB and a 13A plug top fuse cannot discriminate, what is the point in having them in series with each other?

 

[sparkybird]

What sort of job do you do to have to get to work at 5 am on a Saturday? Wasn't it still dark then?

 

[Steve]

It was dark when i got up at 4. I work in a small shop (in a big chain) and we had to get there at 5 because the top bosses from head office were coming to see the shop at 8, and we have just had a refit so had to get the shop looking good.

I dont get up at 4 every saturday, and i wouldn't if they paid me to either. Feel rather tired now.

The power loss meant the cctv monitor above the tills reset its image and was showing the wrong camera, which we hadn't noticed until one of the bosses told us when he came.

 

[plugwash]

the main point of the plug fuse is to protect the flex

sure there are some situations in which a B32 will trip before a 13A plug fuse but that doesn't mean that the plug fuse doesn't serve a purpose.

 

[pdcelec]

The fuse is for overcurrent protection
The mcb is for fault protection

 

[kai]

You can also sometimes find a B16 MCB feeding a 13amp Fuse-connection unit on a household immersion heater / room heater circuit, in a single 2.5.sq.mm. radial circuit.
The B16 MCB gives Short Circuit Protection, whilst the 13amp FCU gives overload protection.

 

[andy]

The power loss meant the cctv monitor above the tills reset its image and was showing the wrong camera, which we hadn't noticed until one of the bosses told us when he came.

i hope you didnt have Sky on instead....

 

[Big_Spark]

Crafty, this is also one reason why the Fuses inside plugs should be checked to ensure they are the correct rating.

Examples:

Average Voltage in the UK at Mains is 238V, so we will asume 240V. (230V ratings in italics)

Any appliance should have the correct fuse in it's plug.

3A Fuse, for items up to a rating of 720W (690W)
5A Fuse, for items up to a rating of 1200W (1.2kW) (1150W {1.15kW})
7A Fuse, for items up to a rating of 1680W (1.68kW) (1610W {1.61kW})
10A Fuse, for items up to a rating of 2400W (2.4kW) (2300W {2.3kW})
13A Fuse, for items up to a rating of 3120W (3.1kW) (2990W {2.99kW})

Now most kettles these days are around the 2 to 2.2kW (2000W to 2200W) rating, consequently a 10A fuse should be fitted in the plug. Whilst this may not stop the MCB operating, it will certainly reduce the chances.

 

[Steve]

you got me thinking there . . . . if i were to get a video recorder (or something with a TV tuner, freeview maybe), could i somehow connect this to the cctv monitor?

 

[Big_Spark]

you got me thinking there . . . . if i were to get a video recorder (or something with a TV tuner, freeview maybe), could i somehow connect this to the cctv monitor?

Start a different thread or the mods may move your post...The answer is yes and no anyway...

 

[Steve]

The power loss meant the cctv monitor above the tills reset its image and was showing the wrong camera, which we hadn't noticed until one of the bosses told us when he came.

i hope you didnt have Sky on instead....

you got me thinking there . . . could i connect a freeview box to the cctv system so it appeared as a camera? the multiplexer has numerous spare connectors, how would i go about this??? (im not really going to do it of course! . . )

(wanted to delete last my post by the way and replace it with this, sorry!)

 

[plugwash]

your freeview box probablly has audio and composite video outputs (and probablly rgb as well but we can just ignore those) the same as a security camera so you should just be able to connect it straight up

if you wan't more detail then you'll have to tell us what connectors you have on your vcr and cctv system.