Overloading an extension lead?

Question

My mum is being a little over paranoid.
She's worried about 'overloading' an extension lead we have, a surge protecting extension lead.

It's got 7 plug sockets, 2 of which are currently in use. I want to plug in a set top box and shes really worried (to the point of arguing with me) that I'll overload the socket

Surely a 7 plug surge protection extension lead is designed to have more than 3 things plugged in, and would be safe to do so.....

They're not even BIG appliances - one is an imac, the other is a radio. Is she being ridiculous or am I missing something?

Answer 1

Your mum is being... shall we say... overly cautious :-)



Check the maximum current rating of the extension lead (should be written on it). It will probably be 13 Amps or 10 Amps. Let's assume 10A. Power = current * voltage, so the total power consumption of all the appliances connected to it should not be more than 10 * 240 = 2,400 Watts (I'm assuming you're in the UK and have 240V mains).

Look on the back of your devices or on their power supplies for the power ratings. You will probably find that all added together they don't add up to anything like 2,400W.



Also there will be a fuse in the plug for the extension lead. That will blow if the total current gets too high.

Answer 2

She is being overly cautious, as people say. The things you name are very low power usage and you could fill the strip with things like them and not reach a tenth of its capacity. As stated, it should have a breaker that will trip before the cord gets overloaded. To trip one sold in the US, you would have to plug in two of those small heaters sold to go under desks (which are about 12-14 amps each while the power strips are rated at 15 amps total) or a hot plate for cooking plus a computer, printer, display, etc. all at the same time.

Answer 3

You need to supply data. The 3 items could be 10 watts apiece, with a total of 30 watts, which is nowhere near the max rating. 30 watts is about 1/4 amps. (assuming US 120 volts)



Or they could be 1000 watts each for a total of 3000 watts, or 25 amps, which would overload any outlet strip. The number of outlets has nothing to do with the ratings.



Most outlet strips have a circuit breaker in them, and the outlet the strip is plugged into also is protected by a breaker or fuse, located in your breaker box or fuse box.





So, bottom line, to convince your mother, get the power or current ratings of each appliance, add them up. Get the ratings of the outlet strip. It's printed on it somewhere, perhaps on the cable.



.

Answer 4

It will be OK. Divide the wattage of your connected appliances by the voltage you are using. EG a 1kw fire divided by 240 = about 4 and a bit. This last number is the ampage. Do not let your total ampage exceed 13. (Add together the wattage for all the connected appliances)

Answer 5

You are telling just the number of plug points but the current carrying capacity of the wire is important

If it can take the load current amperes, it is okey..