Why can't I have too many devices on 1 outlet?

[QueenZ]

Hello, I've heard that you can't put too many devices on 1 wall outlet like you can't run your computer, refrigerator, oven and a bunch of other devices that need a lot of power... why is that? Why do you have to slit them between different wall outlets? I'm confused....

 

[Knobhead]

Because these don't fit in a plug top.
View attachment 11976
End of subject!

 

[QueenZ]

well you can use an extension cable... like this..

 

[QueenZ]

and then another extension cable on top of that if you like ...

 

[RISElectrical]

This is basic electrical safety.... Come on!

 

[QueenZ]

come on... I'm a complete newbie....

 

[kingeri]

You're winding us up, surely??

 

[QueenZ]

Oh... can someone please help me understand this..... I'm not good with electricity... guys....

 

[snowhead]

Is this going to be a whole series;

Why does electricity have to have a closed cct?
What are Alternator brushes for?
Why is there no current in the neutral?

Now This question??

You can have as many appliances as you like connected to one outlet, if the total power they take is less than the (fused) protection for that outlet there won't be a problem.

 

[alli]

If you take a ring final circuit protected by a 32Amp MCB/fuse. If you plugged in 4 13Amp heaters you would draw 52 amps which would trip/blow the MCB/fuse. If the MCB/fuse was not there then you would be drawing more current than the cable can handle, which results in a lot of heat being created and the cables could melt and catch fire!

The same applies to a socket outlet. for arguments sake if the socket is only rated to have 13Amps drawn through it and you installed a plug multiadapter that didn't have a internal fuse and plugged in 2 13Amp heaters then you would be drawing 26Amps through a device that is only suitable for 13Amps, but this time the MCB/fuse protecting the circuit wouldn't trip/blow, then the chance of excess heat and fire is a real possibility.

The safest way to plug several items into one socket is to use a extension lead with 4/6 sockets built it. These have a 13Amp fuse in the plug, therefore it doesn't matter if you plugged in too high a load, it would just blow the fuse before any damage to the cabling or socket was done.

Its easy to work out how many appliances you can add to an extension cable, just look at the plates for there power consumption and keep adding it up until you reach 13Amps which is the rating of the fuse.

 

[QueenZ]

oh ok... that makes sense..... thanks

 

[QueenZ]

So basically I should be able to plug in as many appliances as the CB/fuse allows if I have good enough cables for the outlet that can handle the current... right?

 

[alli]

Your fuse should always be rated less than the current carring capacity of the cable. The fuse is the weak link and should blow before any damage to the cable occurs.

If the circuit has been designed properly with consideration to any necessary derating of the cable due to the installation methods (i.e. installed through insulation etc.), then yes, you can load the circuit up to the rating of the protective device.

With the increase of electrical appliances it is normally good practice to have the kitchen on its own circuit due to washing machine, dishwasher, tumble dryer etc. being high current using equipment. If these where on the same circuit as the rest of the ground floor then the protective device could keep operating which would be very inconvienient. This shows that at the design stage it is important to consider the possible loadings of a circuit, especially ring final circuits that can have anything plugged into them. It will always be a best guess.

 

[QueenZ]

I see, but theoretically we wouldn't need to have several circuits if we could have very good, thick wires for our one circuit that can handle the amount of current we need, right?

 

[trev]

Are you starting out in the trade Queenz or just inquisitive?

 

[QueenZ]

Are you starting out in the trade Queenz or just inquisitive?

Just curious.... Wanna know how stuff works... and how not to burn my house down...

 

[keniff]

Not talking about earth leakage here are you? From computers and such....

 

[QueenZ]

Nope... what is that?

 

[alli]

In theory, yes you can increase the CSA of the cable which will allow a higher design current to be drawn. You do need to give consideration to the pitfalls of doing this. If your supply from the DNO is 100Amps on 35mm CSA tails protected by a 100amp fuse, why isint the whole house wired in 35mm cable? .............Cost, Terminating cables in accessories etc, also if there is any problem with the cabling like a dead short then the main fuse will blow and the whole house will be without power.

Therfore if you devide the circuits up, you can use smaller CSA cables, which are protected by smaller rated protective devices which will hopefully confine any problems to that circuit.

 

[QueenZ]

In theory, yes you can increase the CSA of the cable which will allow a higher design current to be drawn. You do need to give consideration to the pitfalls of doing this. If your supply from the DNO is 100Amps on 35mm CSA tails protected by a 100amp fuse, why isint the whole house wired in 35mm cable? .............Cost, Terminating cables in accessories etc, also if there is any problem with the cabling like a dead short then the main fuse will blow and the whole house will be without power.

Therfore if you devide the circuits up, you can use smaller CSA cables, which are protected by smaller rated protective devices which will hopefully confine any problems to that circuit.

Perfect, that pretty much explains everything, thanks a million! :aureola: