# extension leads guide + help

#### EFLImpudence

On the note of the 230 or 240 disagreement lol!
Disagreement?

Would I be correct is just using a safe margin for example if its a 13amp extension lead it will be 13 x 230v = total load not to exceed 2990watts or 13 x 240v = total load not to exceed 3120watts.
You can use 240V as that is what all the manufacturers will quote on the equipment.

So to make it easy to understand I could assume a number to act as a safety zone that is less than both of the above numbers. Say 2800watts total load. So i could take any 13amp extension lead and use 2800 watts as its Max load figure. this way I'm lower than both 13 x 230 and 13 x 240 so therefore using 2800watts as my 'do not exceed' figure I in theory can overload the extension lead and all should be safe enough.
You will be perfectly safe with 3,000W.

The point really is that you are using Watts which if you multiply Amps by 230V will give a lower Wattage so be extra safe.

We, on the other hand tend to use Amps so if you have a 3,000W Immersion heater this will be stated by the manufacturer as 3,000W @ 240V = 12.5A.
If you divide 3,000 by 230 it will give 13.04A but this is not correct because at 230V the Wattage will be less -
Actually 2,755W @ 230V = 11.98A

B

#### busterboy

Sorry about the misunderstanding read the text wrong I thought maybe a disagreement on the voltage ratings. My fault for confusing matters lol!

So is it safe to say that I can count all extension leads that are 13amps at 3000 watts so when I'm adding up the wattage of my devices as to get the total load I can subtract the number I get from 3000 to see how much more the lead can take to stay in the safe zone.

Also I'm counting in watts yes. Is this wrong? Or is using amps easier? I just use watts as most of my electrical devices say its output in watts
(example ..tv output 130w
so I take 3000 - 130 =2870
so this extension lead still has 2870 watts left to keep it in safe zone )

I'm not sure any other way to calculate this. Its just a general guideline I'm trying to follow when using extension leads.

#### JohnW2

Sorry about the misunderstanding read the text wrong I thought maybe a disagreement on the voltage ratings. My fault for confusing matters lol!
You didn't misunderstand or read anything wrong. There's a lot of quibbling going on here and, for your purposes, I would suggest that you just try to ignore it ...
So is it safe to say that I can count all extension leads that are 13amps at 3000 watts so when I'm adding up the wattage of my devices as to get the total load I can subtract the number I get from 3000 to see how much more the lead can take to stay in the safe zone. ... I'm not sure any other way to calculate this. Its just a general guideline I'm trying to follow when using extension leads.
As you say, it's just a general guideline you want - and for that it really doesn't make the slightest difference whether you use 230V or 240V for your calculations. As you've been told, it's not really desirable that you load a '13A' extension lead to anything like the theoretical maximum of 13A - so if you were 'so close' that it mattered whether you used 230V or 240V for your calculations, you'd probably have far too high a load anyway.

Also remember that you hardly need to do the calculations. As several of us have told you, if you avoid loads which are designed to generate heat (other than electric blankets or short-term use of hair dryers etc.), you're not going to get anywhere near 13A - so I really think you are probably 'getting too deep' into all this and worrying unnecessarily.

Kind Regards, John

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#### busterboy

Thanks John
I'm now confident on using and knowing if I stick with devices designed not to generate heat then I'm way off from overloading 13amps.

Thanks for all replays everyone I'm now finished with topic as I have got the advice and answers I was looking for. I appreciate everything thank you.

#### winston1

Of cause not. The current carrying capacity is the same whatever the voltage.
You don't seem to have grasped the difference.

Calling a voltage lower than it actually is will not increase the current.
No, but if you use 230V to calculate the demand then you will be assuming the current is lower than it actually will be.

For example:
A shower quoted at 10kW @ 240V = 41.67A therefore you will require a 45A MCB.
If the manufacturer of your CU does not make 45A MCBs you will have to use a 50A MCB necessitating the installing of 10mm² cable.

However, if you use 230V for the calculations it will be 9.184kW @ 230V = 39.93A so you can use a 40A MCB and 6mm² cable.

My point is that, we hope, the regulation authors realised this and it is therefore acceptable even though nothing has actually changed.

The current will only be increased if equipment is redesigned to operate on 230v. It will be increased even more if this redesigned equipment is then used on 240v.
Equipment doesn't have to be redesigned to run on 230V.
It will just work less well.

And a 10kw 230v shower will take 43.5A, even more on 240V. Lets face it the whole thing is a mess brought on by Eurocrats.

#### EFLImpudence

And a 10kw 230v shower will take 43.5A, even more on 240V.
On the box that will be spelt - 10.9kW @ 240V

Lets face it the whole thing is a mess brought on by Eurocrats.
That may be true but the fact that you don't like it and seem unable to accept it does not alter anything.

#### JohnW2

And a 10kw 230v shower will take 43.5A, even more on 240V.
True, but I think you'd be very hard-pressed to find such an animal. Manufacturers of many things, particular showers etc., quote the power at 240V, not the least because it makes their products sound more powerful than if they quoted the power at 230V!
Lets face it the whole thing is a mess brought on by Eurocrats.
It is a bit of a mess, but it's not going to go away and we have to live with it, and it only adds to the confusion (particularly for people like the OP of this thread) if you keep on going on about it. In terms of this thread, given that (for better or for worse) we are stuck with the 230V 'nominal' voltage, things would be less messy (particularly for this OP) if manufacturers were forced to state power ratings at 230V. Maybe that will come.

Kind Regards, John

B

#### busterboy

Just wondering on extension leads talk here, I'm thinking about making a 10 to 13 Meter extension lead using 3 core flex from my local electric shop. Can any one guide me on what to get or look out for I will need and the proper way to do this:

13 amp plug
10-13 metres of 3 core flex
4 way socket end

Is this correct or do I need any special type of cable for this?

#### JohnW2

Just wondering on extension leads talk here, I'm thinking about making a 10 to 13 Meter extension lead using 3 core flex from my local electric shop. Can any one guide me on what to get or look out for I will need and the proper way to do this:
13 amp plug
10-13 metres of 3 core flex
4 way socket end
Is this correct or do I need any special type of cable for this?
You'd probably have great difficulty in finding the "4 way socket end" in a shop and, even if you could find one, you'd almost certainly end up paying a fair bit more than you would by buying a ready-made extension lead. Don't bother.

Kind Regards, John

B

#### busterboy

Could I take an existing extension lead and just extend the cable between plug and the 4 way socket end? This way I wud only need to buy the cable.

#### winston1

Just wondering on extension leads talk here, I'm thinking about making a 10 to 13 Meter extension lead using 3 core flex from my local electric shop. Can any one guide me on what to get or look out for I will need and the proper way to do this:
13 amp plug
10-13 metres of 3 core flex
4 way socket end
Is this correct or do I need any special type of cable for this?
You'd probably have great difficulty in finding the "4 way socket end" in a shop and, even if you could find one, you'd almost certainly end up paying a fair bit more than you would by buying a ready-made extension lead. Don't bother.

Kind Regards, John

They are available, or certainly were recently. I bought some in Wickes a while back. It is the only way to go if you want a 10 to 13 metre extension lead as ready made ones are shorter than that. If making one the cable needs to be 1.5 mm sq minimum.
Don't even think about extending an existing cable. You may be able to open one up and replace the existing cable with a longer one but many are sealed.

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#### busterboy

Yes I will be making sure to open it up and replace the short cable (2m) with one long 13 Meter piece then reuse the plug on the end. So when I but the cable I have to make sure its 13 amp comparable and 3 core flex at 1.5mm??

#### ban-all-sheds

Lets face it the whole thing is a mess brought on by Eurocrats.
Thanks for posting that - we now have it confirmed that you are an idiot, who bleats on about things from a position of ignorance and can just be ignored.

#### ban-all-sheds

So how do I work out the watts of other devices like my DVR.
Here is a Pic of the power label

View media item 66021
Thanks
That item clearly shows you how many amps it draws, and that's what you need to know, as it is current which matters to the cable, not wattage.

You only use wattage to calculate amps if you have to - no point in trying to calculate wattage when you already know the load in amps.

#### winston1

Lets face it the whole thing is a mess brought on by Eurocrats.
Thanks for posting that - we now have it confirmed that you are an idiot, who bleats on about things from a position of ignorance and can just be ignored.

You are welcome to disagree with me.

Being rude and insulting is another matter altogether.

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