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#7318 01/31/02 03:36 PM
Joined: Jan 2002
Posts: 1
R
Junior Member
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

#7319 01/31/02 04:27 PM
Joined: Oct 2000
Posts: 5,392
S
Member
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
[Linked Image]

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

#7320 01/31/02 06:05 PM
Joined: Oct 2000
Posts: 4,082
Likes: 3
Member
Bob,

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


Guide Information for Electrical Equipment for Use in Ordinary Locations

USE
This category covers relocatable power taps rated 250 V ac or less, 20 A or less, intended for indoor use as relocatable multiple outlet extensions of a 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 an attachment plug and a length of flexible cord terminated in an 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.

INSTALLATION
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.

ADDITIONAL INFORMATION
For additional information, see Electrical Equipment for Use in Ordinary Locations (AALZ).

REQUIREMENTS
The basic standard used to investigate products in this category is UL 1363, "Relocatable Power Taps."

UL MARK
The Listing Mark of Underwriters Laboratories Inc. on the product is the only method provided by UL to identify products manufactured under its Listing and Follow-Up Service. The Listing Mark for these products includes the UL symbol (as illustrated in the Introduction of this Directory) together with the word "LISTED," a control number, and one of the following product names, as appropriate: "Relocatable Power Tap," "Power Tap" or "Outlet Strip."


Bill
#7321 01/31/02 09:17 PM
Joined: Jan 2002
Posts: 163
D
Member
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.

#7322 01/31/02 09:36 PM
Joined: Sep 2001
Posts: 26
J
Member
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.

#7323 01/31/02 10:47 PM
Joined: Oct 2000
Posts: 4,082
Likes: 3
Member
johngeorge,

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

Bill


Bill
#7324 02/01/02 10:41 AM
Joined: May 2001
Posts: 176
W
Member
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.

#7325 02/01/02 12:47 PM
Joined: Oct 2000
Posts: 4,082
Likes: 3
Member
Warren,

[Linked Image] 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'

[Linked Image]
Bill


Bill
#7326 07/03/06 10:48 AM
Joined: Apr 2004
Posts: 812
Member
Sorry for bringing back such an old post.

Quote

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

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).]


Is there anyone on board who knows how to fly a plane?
#7327 07/03/06 03:11 PM
Joined: Jan 2005
Posts: 5,370
Likes: 1
Cat Servant
Member
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.

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