Multiple power strips daisy-chained, code?

Let's face it, the majority of power strips will find a permanent home underneath computer tables, on lab benches and behind entertainment centers. I don't think folks at UL will be so naive as to believe that all Americans would install 10 or more wall-mounted outlets behind their monstrous TV/stereo cabinets.

It would be time that they agree on stuff. Mankind does not need this much redundant (and costly) bureaucracy ;-)

That is true with most any cert. But if you buy from reputable brands such as Leviton you should be ok.

--
Regards, Joerg

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So again: What is wrong with daisy-chaining 15A-rated power strips connected to an outlet that is on a 15A circuit with a 15A breaker in there?

--
Regards, Joerg

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What you are doing is probably quite safe. Unfortunately that may not count.

From the UL White Book: "Relocatable power taps are not intended to be series connected (daisy chained) to other relocatable power taps or to extension cords." No reason is given but some likely ones are in this thread. Chaining violates the UL listing and the fire marshal can legitimately complain. Your problem of many devices to plug-in is common. You could ask the fire marshal what his suggestion is. You could use one strip that is switched and one that is not switched with each plugged into half a duplex outlet. But then you need strips that have enough outlets.

Wiremold makes surface wiring channels and boxes that can be used to pretty easily add outlets. Or you could permanently add lengths of plug-mold - Wiremold with outlets every 6 inches. This is probably what a fire marshal would like. They probably would have to be installed by an electrician. Like letterman I have a cord connected length of plugmold on my work bench. The fire marshal probably wouldn't like it.

And from the White Book: "Relocatable power taps are not intended to be permanently secured to building structures, tables, work benches or similar structures ...." I remember when outlet strips had mounting holes.

======================================== Unfortunately Joerg said the magic work "surge" and attracted the troll-formerly-know-as w_tom.

For reliable information on surges and surge protection read a guide from the US NIST at:

Or a more technical guide from the IEEE:

Complete nonsense.

Service panel suppressors are a good idea. What does the NIST guide say? "Q - Will a surge protector installed at the service entrance be sufficient for the whole house? A - There are two answers to than question: Yes for one-link appliances [electronic equipment], No for two-link appliances [equipment connected to power AND phone or cable or....]. Since most homes today have some kind of two-link appliances, the prudent answer to the question would be NO - but that does not mean that a surge protector installed at the service entrance is useless."

Service panel suppressors do not prevent high voltage between power and phone/cable wires. The NIST guide suggests most equipment damage is caused by high voltage between power and signal wires.

Because of that all interconnected equipment needs to be connected to the same plug-in suppressor, or interconnecting wires need to go through the suppressor. External connections, like phone, also need to go through the suppressor.

w has a religious belief (immune from challenge) that surge protection must directly use earthing. Thus in his view plug-in suppressors (which are not well earthed) can not possibly work. The IEEE guide explains plug-in suppressors work by CLAMPING (limiting) the voltage on all wires (signal and power) to the common ground at the suppressor. Plug-in suppressors do not work primarily by earthing (or stopping or absorbing or magic). The guide explains earthing occurs elsewhere. (Read the guide starting pdf page 40).

The village idiot ignores what his own hanford link says. It is about "some older model" power strips and says overheating was fixed with a revision to UL 1449 that required thermal disconnects. That was 1998. There is no reason to believe, from any of these links, that there is a problem with suppressors produced under the UL standard that has been in effect since 1998. None of these links even say a damaged suppressor had a UL label.

And all make plug-in suppressors except SquareD.

For it's "best" service panel suppressor SquareD says "electronic equipment may need additional protection by installing plug-in [surge suppressor] devices at the point of use."

For real science read the IEEE and NIST guides. Both say plug-in suppressors are effective.

There are 98,615,938 other web sites, including 13,843,032 by lunatics, and w can't find another lunatic that agrees with him that plug-in suppressors are NOT effective.

And w can not answer simple questions:

- Why do the only 2 examples of protection in the IEEE guide use plug-in suppressors?

- Why does the NIST guide says plug-in suppressors are "the easiest solution"?

- Why does the NIST guide say "One effective solution is to have the consumer install" a multiport plug-in suppressor?

- Why do w's "responsible companies" make plug-in suppressors?

- Why does "responsible company" SquareD say "electronic equipment may need additional protection by installing plug-in [suppressors] at the point of use"?

--
bud--

What about systems where Neutral is not connected to ground? (europe) Shall the cable and phone line shields be connected to ground?

Why is it that power strips -- some of which only have four outlets -- require circuits breakers but extensions cords -- some of which have three outlets -- do not?

I agree that the quality/effectiveness of the surge protectors in many power strips is questionable. On the other hand, I also think that those selling surge protectors tend to overstate the potential hazard of not having one... although I suppose it depends on where you live and just how bad your power really is.

Thanks for the picture links; those are a bit off-putting!

---Joel

Only if the power strip you're using has the outlets "side by side" rather than in-line. This does seem to becoming the more popular style, though, for whatever reason.

There are some power strips with rotating sockets (e.g.,

-

- I have a couple, and they're great!). Also some "medussa" type power strips with just 6 individual outlets hanging, e.g., 6" from a big "tap."

And of course plenty of power strips that try to make some accomodation for wall warts.

---Joel

Only

So again: they're not rated for such use.

Only

So again: If it clearly says 15A on there, why not?

:-)

--
Regards, Joerg

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Joerg, I'm no electrician but I _think_ I've got it right when I state that U.L.'s mission is to certify the inherent safety of devices, as opposed to certifying said devices for any specific uses. My rifle doesn't explode when I fire it (properly constructed and therefore safe to use) but this does _not_ mean that it won't kill when improperly used.

Hmmm .... I wonder if U.L. has any regulations at all regarding screw mounting slots on strips. Probably, but I would guess that their extent would probably go no further than making sure a mounting fastener could not contact any "hot" part of the strip.

Your fire guy would suffer apoplexy were he to see how this electrical engineer uses power strips in his home. Not only do I have hook-ups similar to the one you describe but I use 12-14" "pigtails" to attach my wall-warts to strips and wall sockets alike. Said pigtails are commercial ones and have molded connectors. I prefer the pigtails that have a socket integrated in the plug so that plugging a pigtail into a wall socket doesn't result in the "loss" of that socket.

Does TUV have anything to say about the ways in which power strips are used in Germany?

--
Michael

Homeowners can get away with a lot of sins that commercial establishment's can't. Your church is a "commercial" establishment, for this purpose.

"UL approved" doesn't mean it isn't dangerous. UL is not the controlling authority *anywhere*. NFPA is, though your town/city/county may have some differences, mostly the controlling NEC publication date.

...unless they're counterfeits. ;-) Using a counterfeit of "most any cert" isn't as likely to get someone killed.

need

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Ever hear of a "fire marshal"? "Ambulance chaser"? Insurance company?

need

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Sure but this does not answer the technical question why it dangerous. The fact that some local authority says so does not mean it's true. Since they have the final say anyhow I am looking for some official document that says it's ok, in order to convince them. The only alternative is punching holes in the wall (again ...), running oodles of feet of wire, set a couple of new breakers, with some luck the panel ain't big enough, and so on.

--
Regards, Joerg

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However, agencies must work together. For example, if a code would say that power strips are not to be mounted anywhere but UL blesses lots of them with mounting hardware/moulding (which they do) then this would not be right.

All I remember is that the safety guys I experienced never complained about the connections of power strips. As long as they were rated

230V/16A. They did ask me to unplug them once though, so they could be tested for proper functionality of the PE. I still have one of them somewhere, with a very official looking yellow TUEV sticker.

--
Regards, Joerg 

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need

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there?

It likely isn't, if you know what you're doing. It isn't listed to be used that way since no one wants to stand behind every combination of uses. Again, these things are for temporary use only.

No, it means that they're the authority. Seriously.

If you can get a PE to say THAT APPLICATION is OK, and stand behind it with his license and LEO insurance, go for it. That's the only way to trump an inspector, even if the inspector is wrong about the code (or law). I ran into this when building a garage. The inspector was clearly wrong (and had failed his exam, three times) but was still the town inspector. His ignorance (and stubbornness) cost me over $1000. A PE would have cost even more (and likely died laughing).

U.L.'s mission is to

devices for any specific

therefore safe to use) but

mounting slots on strips.

than making sure a

Since when did the law have to be "right".

engineer uses power strips in

use 12-14" "pigtails"

commercial ones and

in the plug so that

socket.

in Germany?

We were only allowed to use specific power strips. Generally they were made with the "Wire Mold" channels and industrial/hospital grade outlets and SO cable. The box store variety were forbidden. They'd cut the plug off, then scream and yell at your manager if you were caught with one. Interestingly, the power distribution widgets that fit under the monitor with switched outlets in the back were allowed.

[...]

If that is so then UL should definitely stop certifying power strips that have clearly visible mounting hardware and clear instructions on the packaging on how to screw them down onto wood and drywall. Heck, one even came with two screws and wall anchors.

I know. They can sometimes stop you just because they can.

A friend of ours said he always leaves an obvious but not blatantly obvious bug in his electricity hook-ups. He said the local inspector hates do-it-yourselfers and then gets a high when he finds the error. "Aha, I knew it!" Then you have to pay for a 2nd inspection where, of course, the "error" is corrected. Cheaper than if he doesn't find an easy bug and starts chasing (expensive) hairs in the soup.

This inspector is said to be very friendly. So if I could show him an official document that either endorses multiple properly rated power strips or clearly does not prohibit them I might be able to convince him. However, it seems this whole area is as muddy and obscure as I had assumed :-(

--
Regards, Joerg

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I believe there is more than one earthing scheme used. My understanding is that neutrals are earthed somewhere, maybe only at the utility transformer end. And "ground" might refer to a power system grounding conductor or the earth.

In general, I assume that plug-in suppressors in Europe would have a power "ground" wire (connected to earth), and that at a plug-in suppressor the cable ground would connect to that wire (or could be clamped to it) and all other wires - power, telephone, cable center conductor - are clamped to the same ground/earth wire at the suppressor. That means the voltage between wires going to the protected equipment is safe for the protected equipment.

In the US, I believe connecting the neutral and "ground" wires together at the service and earthing both at the building is an advantage for surge protection. If a strong surge comes in on 'hot' power wire there is arc-over when the voltage from busses to enclosure(/"ground"/neutral/earth) reaches about 6kV (US). When established, the arc voltage is hundreds of volts. This both limits the voltage that the building 'sees' and dumps most of the surge energy to earth.

And the universal US practice of having a phone wire entrance protector that limits the voltage from phone wires to the power ground system is also a major advantage. I believe BT does not usually do that. Don't know about the mainland. US practice also has the cable shield, at building entry, connected to the power ground system. Short connections from phone and cable entry protectors to the system ground at the power system is one of the major protection schemes in the IEEE guide. Currents to earth from a strong surge can lift the building "ground" well above "absolute ground". A significant part of the protection is keeping the power and phone and cable wires near the same potential.

Don't know if that completely answers your question.

--
bud--

UL is about safety of the device. Other codes address other issues such as how electric is installed (ie NFPA) or how all devices (UL listed or others) are used (ie state fire codes).

Some states (ie NY) that any power adaptor (UL or other) can only connect to a wall receptacle - not to any other adaptor. Others (ie college campuses) ban all but one type of power strip - and demand it be UL listed and only connect directly to a wall receptacle, etc.

Each organization has specific domains to regulate or list. You are required to meet some codes (ie state fire coded) but are encouraged to use only better (ie UL listed) devices. Some locations permit using non-UL listed devices. Others do not.

Any power strip should only connect directly to a wall receptacle. Daisy chaining power adaptors is simply a bad idea in any jurisdiction. Especially in a building that will house a crowd or that remains unsupervised for long periods. No way around that safety no matter how others may rationalize it or use profanities.

Some power devices without UL listing are acceptable in some environments. But since it is being used in that environment, it should also be UL listed. Would you apply same commercial restrictions also on all homes? The code only appears complex because it is also flexible. Your church should meet stricter requirements. Even if not required by code, daisy chaining power adaptors in the building is a bad idea.

Adding additional wall receptacles is usually quite easy. And safer according to that fire marshal.

The only way to determine this is to ask the fire marshal if he's forbidding it, and if so, ask him to show you chapter and verse of the applicable reg.

If he's just "unhappy", but can't show you the reg, then apologize for his unhappiness and thank him for his time.

Cheers! Rich