I have seen computer labs that use multiple outlet strips with overload protection. Due to multiple workstations, I have seen these strips daisy chained together to get to the wall outlet.

In theory, I guess any overload would open the breaker up stream. However, I am unable to find anything in the codes stating this is allowed or not. I'd appreciate anything you know about the issue.

thanks

Bob Morris

Bob,
this is a start.......

(2) Total Cord-and-Plug-Connected Load. Where connected to a branch circuit supplying two or more receptacles or outlets, a receptacle shall not supply a total cord-and-plug-connected load in excess of the maximum specified in Table 210.21(B)(2).

Table 210.21(B)(2) Maximum Cord-and-Plug-Connected Load to Receptacle

1)----Circuit Rating (Amperes)
2)----Receptacle Rating (Amperes
3)----Maximum Load (Amperes)

1)------------2)--------3)
15 or 20----- 15------ 12
20------------20------ 16
30------------30-------24


[This message has been edited by sparky (edited 01-31-2002).]

Bob,

According to the UL 'White Book' this would be a violation. I have Highlighted a section for emphasis:

A nice feature of this board is you get to have folks like Bill do a lot of leg work for you.

I've been enforcing this "no daisy-chains" at work for years but didn't know exactly what standard prohibited this practice.

I believe the outlet strips were classified as extension devices and only allowed as a "temporary" connections such as the extension cord. When people began to complain, U/L and other labs tested these devices in a different manner and now can be used as the listing has stated. A lot of requirements are not contained in the NEC, but have to be researched in other directories. The temperature limitations of terminals and conductors were in the U/L White Book long before the NEC saw a need to publish it in their code.

johngeorge,

As you described, I have one right in front of me that is called a "Temporary Power Tap"

Bill

Bill
How long has it been "Temporary"?

I recently visited a plant in the St. Louis area that the IT department had about three or four of these daisey-chained together. Only computers were plugged in, no printers, so they didn't trip the breaker. Our team leader pointed this out to the owners, but to no avail because the whole department is relocating soon. And this is one of the relocation reasons given, not enough receptacles and circuits in the present location.
Another thought. Although UL says it is a violation, most communities adopt ONLY the NEC which then has the force of law behind it.

Warren,

Temporary is such a relative term, isn't it? Mine does get unplugged several times per year when going away or during severe storms, but aside from that it stays where it is. So, .. one might say that it was 'Perpetually Temporary'


Bill

Sorry for bringing back such an old post.


I have two lying here in front of me, one in use, one whose plug was a dog-treat. One is the older metal style with the replacable receptacles (and a 10ft power cord), the other is a modern Leviton plastic model. None of them say "Temporary Power Tap." They both say "Relocatable Power Tap," and are UL Rated as such.

Ian A.

(Edited a 1001 times to make the QUOTE thingy work.)

[This message has been edited by Theelectrikid (edited 07-03-2006).]

I think we're -again- confusing two different UL classifications.

"Temporary power strips" are one thing, and intended for temporary use. NEC defines temporary as 90 days or less.

However, similar looking strips, with surge suppressors, are listed to a different UL standard, and are allowed for "permanent" use.
They are still not intended to be "daisy chained," though. From a practical standpoint, even though the little breaker might say "15 amps," they really aren't stout enough to carry that kind of load for any length of time. In practical terms, 5 amps would be a more realistic load; the breaker is only there should something bad happen.

John both products are under the same listing.


RELOCATABLE POWER TAPS
(XBYS)
USE AND INSTALLATION

This category covers relocatable power taps rated 250 V ac or less, 20 A
or less. They are intended for indoor use as relocatable multiple outlet
extensions of a single branch circuit to supply laboratory equipment,
home workshops, home movie lighting controls, musical instrumentation,
and to provide outlet receptacles for computers, audio and video equipment,
and other equipment. They consist of one attachment plug and a
single length of flexible cord terminated in a single enclosure in which one
or more receptacles are mounted. They may, in addition, be provided with
fuses or other supplementary overcurrent protection, switches, suppression
components and/or indicator lights in any combination, or connections
for cable, communications, telephone and/or antenna.
Relocatable power taps are intended to be directly connected to a permanently
installed branch circuit receptacle. Relocatable power taps are
not intended to be series connected (daisy chained) to other relocatable
power taps or to extension cords.
Relocatable power taps are not intended for use at construction sites and
similar locations.
Relocatable power taps are not intended to be permanently secured to
building structures, tables, work benches or similar structures, nor are
they intended to be used as a substitute for fixed wiring. The cords of
relocatable power taps are not intended to be routed through walls, windows,
ceilings, floors or similar openings.
Relocatable power taps have not been investigated and are not intended
for use with general patient care areas or critical patient care areas of
health care facilities as defined in Article 517 of ANSI/NFPA 70, ‘‘National
Electrical Code’’ (NEC).
Component power taps may be factory installed on relocatable equipment
intended for use in general patient care areas or critical patient care
areas as defined in the NEC. They are intended to comply with 60601-1,
‘‘Medical Electrical Equipment, Part 1: General Requirements,’’ and 60601-
1-1, ‘‘Safety Requirements for Medical Electrical Systems.’’ Refer to Medical
Equipment (PIDF).

[This message has been edited by iwire (edited 07-03-2006).]

"Relocatable power taps are not intended to be permanently secured to ... tables... nor are they intended to be used as a substitute for fixed wiring."

What about the power strips sold by the manufactures of office furniture and come with instructions stating they are to be fastened to it? I'm setting up a new lab at work, and was told to use the power strips sold by Anthro instead of being given the number of receptacles I requested. They appear to be regular strips that mount with the keyhole slots on the rear.

And so they are meant to be "hung" from those keyholes like a picture on a wall.

Technically, they aren't fastened in place.

The temporary power strips are tested under UL standard 1363, and are not for permanent use.

Add a surge suppressor, however, and the item is now a "Transient Voltage Surge Suppressor" and may be permanently uses. It is evaluated under UL 1449. The packaging will indicate this.

Many thanks to Safetygem, who dug this up the first time.

"not intended to be" does not mean it can not be used in that manner.

From the standpoint of each "temporary power strip" in a daisy chain, each sees a legal installation - a male plug placed in a female recept.

While one might not want this type of installation, I suspect that it is legal.

"Not intended to be" I think means that it hasn't been tested or listed for that useage.
Why should UL list something for its unintended use?

John the simple addition of surge suppression does not change the listing.

Did you bother to read what I posted?

Here is the short version.


Now there are other products that look somewhat like RELOCATABLE POWER TAPS that are listed differently.

They are made for permanent mounting to computer equipment racks and may or may not have surge suppression.

These might be what 'SafetyGem' found.

I have a 'plug strip' in my basement with surge suppression it is still UL tagged as a RELOCATABLE POWER TAP.

So just because a plug strip has surge suppression in it you will have to look at the UL tag to see how it is listed.


[This message has been edited by iwire (edited 07-04-2006).]

I was in the computer biz for 30 years and the last 4 I was also a certified IAEI electrical inspector. Suffice it to say they thought I was speaking a foreign language when I started pointing out NEC violations in the way they did things.
Plug strip abuse is the most common violation, followed by orange cords and "penetrations". There were even some glaring problems in listed IBM equipment nobody wanted to acknowlege ... like the 14ga power cord to 3420 tape drives, protected by a 60 or even a 100a breaker (with the mod 2 feature).

"Orange cords"?

www.electrical-contractor.net/ubb/Forum4/HTML/000183.html

[This message has been edited by renosteinke (edited 07-04-2006).]

Orange cords ... Carol (or similar) 25' and 50' extension cords.
The floors under computer rooms used to be full of them.

I had a belkin one that went up in smoke luckily I was there to unplug it at that moment or I don't know what would have happened. Upon closer inspection,I took it apart to see what failed and it looks like the little neon bulb in the power switch shorted out or something It was flickering for a while I just thought it would go out and not short out.

I dont know what the strips are like in the US but here in Australia they all have an overload protection button that pops as soon as you get near the rated 10amps(at 240v). If they are fitted with an overload i dont see what the issue is. Even daisy chained it doesnt pose a risk if they all have overload protection. I will admit its not good practice but almost impossible to police.

The ones in the US also have a circiut breaker rated for 15 Amps or 1875 Watts at 125 Volts and your not supposed to dasiy chain them but I guess if you do and you overload the chain the one first in line will probably trip first.

Trouble is, as has been pointed out in earlier threads on this topic, those cute little overloads in the power strips are not especially reliable.

As I recall, Trumpy had one (10A) which held on up to about 30A before going up in smoke.

Almost as bad as daisy-chaining these things is the power strip with coffee pot, microwave, etc all plugged in, the plastic around the socket turning a sick brown colour from the overload, and nobody even noticing the hazard steaming away under their noses.

Just a note on power strips, i hope everyon is aware , there are strips out there that have a UL sticker, and are knock offs, not ul approved, some of our commercial accounts, have had them go up in flames, and one account called us in a panic after the fire trucks left, please tell us what is wrong with our electric?, after sifting thru the ashes, i found a UL sticker, contacted ul, and gave them the information, they told us that there was no listing for that product, it was a knock off, so you may want to check the listing, also check with ul to be sure it is a listed product.

Yeah. There have been plenty of instances of recalled items because of bogus UL listing stickers.

You want silver sticker. We sell to you silver sticker. You send to me 10 cents per eaches to invoice.

A few weeks ago, a secretary at work called me and said that the powerstrip under her desk was making a crackling noise. I told her to yank the plug out immediately.

When I went up there with a replacement, I took a look at the old one. The switch had gone stiff and the plastic housing on the power-bar had started to distort. It also felt warm in that area.

What was plugged into this thing? A lone electronic typewriter!

[This message has been edited by SvenNYC (edited 08-07-2006).]