So how many appliances can I plug in there before starting an electrical fire?

February 22, 2012 7:32 PM

I have a two-plug outlet with a three-plug adapter, meaning that I have four things plugged into the outlet. Am I going to set my sublet apartment on fire? Or rather, how can I keep from doing so?

The items are:

1. A 60 watt lamp
2. A Seagate external hard drive
3. An Apple Airport Extreme wireless router
4. An AT&T U-Verse modem/wireless router

The apartment has likely seen no maintenance in fifteen years (rent control), so maybe the wiring is old too.

Is this setup cause for concern at all? I know nothing about electricity.

Thanks.

posted by kensington314 to Home & Garden (9 answers total)

I think you'll be fine. The lamp draws a moderate amount of power, the other stuff doesn't draw much.
posted by itheearl at 7:52 PM on February 22, 2012

Wall outlets are typically rates at 10 amps. I just looked at my stuff that's similar to yours.

1: 60W at 115V = 0.5A
2: says 0.5A on it
3: says 25W = .22A
4: says 0.3A on it

for a total of 1.52A which is obviously less then 10A so your fine on power.

You don't normally do maintenance on electrical wires so that's certainly not a problem.

Houses have circuit breakers to deal with over-current problems, they're designed to prevent your house from burning down.

You're 100% fine.
posted by Confess, Fletch at 7:55 PM on February 22, 2012

You're fine.

(at one point I had a server, a photoshop workstation, router, modem, four external hard drives, speakers, phone, and desk lamp all in one 80-year-old outlet. No problemo.)
posted by notsnot at 8:04 PM on February 22, 2012

Response by poster: Thanks to all three of you!
posted by kensington314 at 8:04 PM on February 22, 2012

The amount of current you're drawing is fine, so my main concern would be with how secure the connections all are. The 3 plug adapters I've seen look like a T sort of when plugged in. Plugging 3 things into one of these and plugging it into a wall socket tends to make the adaptor sag out of the socket. It's best for all your stuff to be fully plugged in. If you have one like this it would be better to be using a power strip or something like that.

What is said up above about circuit breakers is true - it's not important what the amperage of the breaker is, by code the wiring (should) be able to handle more current than it would take to break the circuit. Circuit breakers are made with safety in mind and when they fail it tends to be on the safe side - they usually break so that current won't flow at all, as opposed to breaking so that they let any amount of current through.

What you have is probably fine, I'm just saying you should make sure it's not at risk of having some of the plugs' prongs exposed.
posted by RustyBrooks at 9:09 PM on February 22, 2012

As a rule, anything that produces a lot of heat is consuming a lot of power. That would include small things getting very hot (like light bulbs) and big things getting slightly warm (like refrigerators -- the back coils get warm) and certainly includes toaster ovens and hot plates, which consume 1000 Watts easy.

Small electronics consume trivial amounts of power.

If you want a more analytical answer, use Confess-Fletch's answer above to guide you in adding up the currents. Anything that consumes AC power should have a power rating on it in Watts (W); take that number (e.g. 60W) and divide it by 120V to get the current in Amps (A). See Ohm's Law for more on that conversion. As long as the currents add up to less than 10A, you have nothing to worry about. Above 10A, it gets more complicated because you have to see what kind of circuit that wall outlet is one, what else is on the circuit, etc.

Anything that consumes DC power by using a power brick (like a laptop) or a wall wart (like a router) either will have the AC power rating on the brick or consumes a negligible amount of power. In case you happens to notice it, be careful not to use the DC current rating (something like "12 VDC 2 A"); that will seem artificially high and will mess up your numbers.
posted by intermod at 9:27 PM on February 22, 2012

As everyone has said, you're fine, since most of those things don't draw much power.

For an example of what could be a problem: two halogen torchieres (500W each!) and a big CRT TV can get you well above 10A. Add a microwave or an air conditioner or a vacuum cleaner and you can overload the circuit. The breakers will generally trip before anything dangerous happens, of course, but it's not a good idea to push that line regularly.

You don't normally do maintenance on electrical wires so that's certainly not a problem.

The physical outlets do eventually get worn and sprung and make bad contact and (potentially, worst case) get hot enough to start fires or whatever. I think that's more like a 50-year maintenance thing than a 15-year one, though.
posted by hattifattener at 1:01 AM on February 23, 2012

I agree you're fine and I second the power strip idea.
posted by maxwelton at 1:38 AM on February 23, 2012

Seconding with what intermod said about devices that generate a lot of heat, and everyone else who suggested a circuit breaker (which you should have anyhow).

My previous apartment had two power circuits, clearly split between the north and south sides of the apartment. On one particular circuit, I had a 42" plasma, DVD, x-box, about 6 ceiling lights, a clock radio, a ceiling fan, a few other bits and pieces... but crucially, a portable heater and an iron. I could have any or none of those devices all running and everything would be fine, other than the last two. But as soon as I turned on the heater and the iron at the same time, BOOM... circuit breaker tripped.
posted by Diag at 3:57 AM on February 23, 2012