This is one of those “I’m sure this is safe, but I’m going to ask just in case questions”.
I have a 6 plug powerboard that has run out of plugs. (Plugged into it is a stereo, PC, monitor, speakers, printer, clock radio, lamp, modem - or at least I’d like to have all of these things plugged in at the same time.) While I don’t have an 8 plug powerboard, I do have a 4 plug powerboard. Is it safe to plug the 4 plug powerboard into the 6 plug powerboard so that I can plug in 9 different things?
(I’m reasonably sure that the number of things plugged in doesn’t matter - it’s the total current that does. Something like 15 amps IIRC. Just would like to be sure before I start a fire.)
These are all pretty low power devices, you should be fine. Put the PC and monitor on the first plugboard, and put the punyest doodads (clock, radio, modem) furthest downstream. Just (or Just even) don’t start plugging in 2KW heaters.
In any case if you would blow the fuse in the plug at the wall socket if you tried to draw too much juice.
Overloading the circuit is not the only concern. Overloading the wire is a concern. Even if the circuit can provide, say, 20 amps, the cable that you’re plugging into the wall might overheat at that load and cause a fire.
I’m not saying that the situation in the OP is dangerous, but it is dangerous to say that just because you don’t trip a breaker, your arrangement is therefore perfectly safe.
He’s talking about the breaker in the outlet strip, not the mains breaker for the wall outlet. These are (or at least should be) sized for the wire being employed in the strip’s cord. If there’s a UL sticker on it, he should be fine. If not, I’d be a little more cautious, particularly if the strip is foreign-made. I recall an extension cord that Colibri sent me for a failure analysis (it burned up and nearly started a fire) which was made overseas and did not bear the UL seal. It was a pretty scary piece of construction, I tell you.
One old-timer engineer of my aquaintance maintained that you should only use distribution blocks in an emergency, and never as a semi-permanent installation. His point was that they often don’t grip the plug and/or contacts as well as a wall socket, and only get worse with age and use.
That’s OK for him to say, but for the rest of us with 20 applicances scrabbling for 4 sockets, we have to use multi-way exension leads. It’s good to check them for quality though, because they do vary. I have one which only makes good contact when the plug is rammed home the last 2mm. That’s not good.
Most applicances (Hi-fi, all TVs except plasma screen, computers, printers, telephones etc.) only take a tiny share of the total current available. As a general rule of thumb, you only need to worry about domestic appliance current consumption if it’s an appliance that generates lots of heat, like a heater, iron, cooker, deep-fat-fryer, hairdryer, washine machine etc. If in doubt, every appliance should have a label that gives its maximum current or power consumption.
If you want to be really safe about it: Each of your appliances should have a maximum current draw listed somewhere on it (this is usually on the back, near where the cord enters the appliance). And both of your power strips should have a current rating listed somewhere on them, also. On the small strip (the one plugged into the big one), make sure that the sum of all of the currents on the appliances is less than the rating of the strip. And on the big strip, make sure that the sum of the currents of all of the appliances is less than the rating of the strip.
If your power strips are made in a first-world country, they should include protection to match their rating, so even if you do exceed the rating, there shouldn’t be any danger. But the protection might be a fuse which has to be replaced rather than reset, which can be rather an inconvenience (and could be dangerous, if you replace it with the wrong fuse). Given how easy it is to add up the currents from the appliances, I would recommend doing that before you just try plugging them all in and seeing what happens.
Hate to thump the tub, but folks aren’t getting the message. The cord which Colibri sent to Q.E.D. had no UL label, but that still doesn’t address those imported products bearing a UL label which was counterfeit. A recent search of the UL website brought up 22 hits for counterfeit labels. This is why we (in the electrical inspection community) continue to preach that flexible cords and outlet strips are not a replacement for fixed wiring in a dwelling. In addition to being a safety hazard, they’re a code violation.
You’re absolutely right, but you and I both know that you’re barking uphill at this point (I love mixed metaphors). About all we can do is educate folks, because they ARE going to use these things. Hell, I use them myself, and I know the risks better than most people here. Some things you can do to minimize the risks:
Never overload them. Always add up the amperage of the devices you’re plugging in, and be sure that the total is well below the max rating of the strip. Never plug high-wattage appliances into them–always plug those directly into the wall outlet. This would include things like hair dryers, coffee makers, microwave ovens, curling irons and anything else with a draw greater than a few hundred watts. Make sure every outlet strip you use has a pop-up circuit breaker.
Look for the UL label. As mentioned above, that’s not always enough, since there are counterfeits out there. To combat this, UL now employs a hologram on its labeling for some products produced in certain foreign countries. In addition, look for telltale signs of low-quality manufacturing: thin cords with no rating information imprinted on them, rough or uneven appearance on molded plastic surfaces, poor alignment of fasteners or poor fitting of parts, plugs not molded onto the cord end, signs of corrosion on metal parts and poor quality printing on labels and packaging.
Don’t abuse the cords. Don’t put heavy furniture on top of them and don’t run them where they can be repeatedly stepped on. Be careful not to run vacuum cleaners with carpet sweeper attachments over them. Unplug them by pulling on the plug, not by the cord.
Never cut off the ground prong in order to plug them into a two-prong outlet. Either hire an electrician to install proper outlets, or at the very least properly use a grounding adaptor. Unscrew the plated screw in the middle of the outlet plate, plug in the adaptor so that the green grounding tab lines up with the screw hole and replace the screw through the tab.
If you spill liquids onto it, remove the power from the outlet, either with a wall switch if applicable, or by throwing the appropriate circuit breaker. After verifying that power has been cut off, unplug and discard the strip. And never use an outlet strip if the cord is frayed or split, or if there are any signs of scorching near any of the outlets or the built-in circuit breaker.
Did I mention not to overload them? Well, I’ll mention it again. NEVER overload them.
Pardon my ignorance but if they are a safety problem and a code violation, what am I supposed to do?
Right now I rent, but when I own my own house, is it even possible to install that many outlets in the wall?
My working desk alone requires about 20 plugs, and it doesn’t get better around the house. To be properly wired I’d require at least 60-70 outlets (and that’s what I’m using now, in a tiny apartment, using surge protector power strips), which comes out to be about 30 outlets per room.
What if I want to move my desk, does that mean I need outlet clusters of 20 outlets on every wall in my house?
Truth is, there’s now way to wire for that many outlets, and it would be too expensive; I say as I look at everything plugged in by my computer. If you follow QED’s advice then you’ll be better off than almost everyone out there.
Truth is that 90% of devices I use in my home are 6->20 volts DC. It would surely make much more sense to have the house wired for 20V DC, unfortunately there’s no standardized plug, voltage or polarity for all these devices. sigh
Is it possible to install that many outlets in the wall? Certainly. A single gang box with duplex receptacle can expand to a four gang box with eight individual receptacles.
For customers with home businesses requiring a large number of receptacles, rather than tearing up the house I’ve installed Wiremold® baseboard wiring systems, such that the needed number of receptacles are provided, together with CAT5 wireway and RJ45 terminations.
Well, this turned out to be more work that I was expecting, but okay, why not. I vaguely remember using the formula P = VI in high school, so I’ll use that when necessary to convert amps to watts.
stereo - 52 W
PC - 300 W power supply
monitor - Label on the back says 1.0 A = 240 W
speakers = 5 W (Not sure if this is right - it just says 5 W on each speaker. Is this RMS (not that I really know how that affects things) or per speaker or what? I’ll call it 10 W to be on the safe(r) side.)
printer = 40 W
clock radio = 5 W
lamp = Let’s assume it may have a 100 W globe at some point
modem = The box says “Input: 9V AC, 1A”. So the power is 9 x 1 = 9 W, right?
Grand total power: 756 W, which is 3.15 A. The label on the 6-plug power board says you can go up to 2400 W, or 10 A. (I’d also check the 4-plug power board, but it seems to have gone missing; I’ll probably be needing to buy a new one.)
Okay, so I’m well within the max output of the power board, but how do I know what the maximum power is for the actual powerpoint? Say I had two 6-plug power boards, each good for 10 A - can I plug one into the other, plug in 20 A worth of appliances, and then plug them all into the same powerpoint?
I’m quite sure the answer is no - but how many amps/watts can I go up to? I said 15 amps in my OP because I vaguely remember my high school physics teacher saying so, but my memory is likely to be wrong.
Missed this at first - maybe that’s what I’m looking for. So 13 amps it is, per powerpoint? 13 is the universal limit? Okay.
By “further downstream”, do you mean the high power things on one board, and the low power things on the other board? Or that I should just plug them in in order from highest to lowest power? How does that help?
Jeepers Just, what time of day it it where you are?
stereo - 52 W – No way does it use this much power continuously, more like 5W
PC - 300 W power supply – I’ll look at this, I’d say 300W is a theoretical figure to cope with multiple drives/fans etc.
monitor - Label on the back says 1.0 A = 240 W – OK
speakers = 5 W – see remark about the stereo
printer = 40 W – again not continously, unless you’re running a newspaper.
clock radio = 5 W – that’s very thirsty for a clock!
lamp = 100 W – OK
modem = 9 W, right? – again this seems OTT, and most of the time it’s doing nothing. The modem supply under my desk says it draws 40 milli Amps from the mains.
The most you can draw from the wall socket is 13A. The fuse in the plug or the board will blow and failing that the breaker back at the junction box will throw.
By upstream I meant nearest to the wall outlet, put the heftier devices on the extender board that is plugged directly into the wall socket so they’re not drawing current though more plug/socket connections than necessary.
All this is a bit nit-picky really since none of the things you’ve mentioned actually uses enough power to cause a problem. Just don’t daisy-chain extender boards and then run your toaster of the last socket.
You are correct. The answer is no. Since all of the current that goes to the second strip must first pass through the first strip, the most you can use is 10A or whatever your powerpoint will supply, whichever is less.
As I type this, it’s about 10 pm, Wednesday night. Lousy Australian time zone, it really makes it difficult to watch Formula 1 live.
Aaah, now I see what you mean. Makes sense.
:smack: Of course, I’m plugging one into the other. Stupid me…
And yeah, all of this is probably useless anyway, 'cause not only will each appliance not be using their maximum output all the time, but I doubt I’ll ever use the lamp at the same time as the PC, for example. But it’s good know anyway.
