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November 2007 

Power Strips and Dangerous Daisy Chains


The supply of readily available electrical 

outlets is inadequate in some buildings, 

especially older ones. To meet power supply 

needs, extension cords or surge protected 

power strips are often interconnected, or 

“daisy chained,” to readily provide more 

outlets and/or to reach greater distances. 

Another common solution is to create 

a “mixed daisy chain,” interconnecting

extension cords and power strips. However, 

interconnecting these devices is a violation 

of Occupational Safety and Health 

Administration (OSHA) regulations and 

the National Electrical Code because doing 

so can cause them to become overloaded, 

leading to their failure and a possible fire. 

(See the Office of Compliance “Extension

Cords” Fast Facts for more information) 

Figure 1: Daisy Chain—Interconnected 

extension cords 

Daisy Chaining Found Frequently 

Daisy chains and mixed daisy chains 

constitute some of the most common 

violations identified during recent Office of 

Compliance health and safety inspections. 

During the biennial inspection conducted 

during the 109th Congress, more than 

2,400 instances of daisy chains and mixed 

daisy chains were observed, accounting 

for approximately 20% of all recorded 

violations. 

Problems 

OSHA regulations require that conductors 

and electrical equipment be used in 

accordance with the conditions under which 

they are approved by a recognized testing 

organization (29 CFR 1910.303(a)). Most 

powerstripsareapprovedforprovidingpower 

toamaximumoffourorsixindividualitems; 

however, when multiple power strips are 

interconnected, the one directly connected 

to the building outlet is often supplying 

power to far more than the approved 

number. This electrical current overload can 

result in a fire or can cause a circuit breaker 

to trip, deenergizing computers and other 

equipment throughout the area. The risk is 

magnified when another outlet in the same 

wall or floor receptacle is also overloaded in 

a similar fashion. When other outlets on 

the same circuit are also overloaded, the risk 

increases. 

Extension cords are sometimes used to 

energize power strips in locations far 

from outlets. Because electrical resistance 

increases with increased power cord length,

interconnecting cords increases the total 

resistance and resultant heat generation. 

This creates an additional risk of equipment

failure and fire, particularly when paper and 

other combustible materials are in contact 

with the wires. Additionally, OSHA’s 

regulations allow extension cords to be used 

only as temporary wiring for up to 90 days.

Unfortunately,once inplace, extensioncords 

tend to become permanent wiring and a fire 

hazard. 

Figure 2: Mixed daisy chain—Power strip 

energized by an extension cord 

Solutions 

Several safe solutions exist. In many cases, a 

powerstripenergizedbyanextensioncordor 

anotherpowerstripcansimplybereplacedby 

a power strip with a power cord of adequate

length to reach an outlet. Alternatively, desks

and associated equipment may be moved so 

they are closer to existing outlets. Other 

times, use of a power strip that is better able 

to accommodate bulkier transformer plugs 

solves the problem. 

Several factors should be considered when 

selectinganappropriatesurgeprotector.Since 

models vary in the amount of current that 

they are rated to safely carry, it is important 

to consider the amperage requirements of 

the devices to be energized. Models vary in 

length of power cord, typically ranging from 

three to15feet. Chooseonewhose lengthis 

most appropriate for reaching the intended 

room outlet. Avoid having too much excess 

cord, andmake sure the surgeprotectorisset 

on its base. Some have swivel plugs which 

makes them easier to connect to the outlet,

and helps to protect the plug and cord from

damage. Check each surge protector to 

make sure it is in good condition for use. 

www.compliance.gov

Only power strips equipped with internal fuses are acceptable as permanent wiring. Those

lacking these fuses are equivalent to extension cords, and therefore may not be used as

permanent wiring. When a power strip is installed, care must be taken to ensure that it is 

not suspended in mid-air by its power cord or cords plugged into it, resulting in excessive 

stress on electrical connections. 

When there are not enough outlets to supply occupants’ needs, one solution is to request the 

installation of additional outlets. Their placement should avoid any need to run any wires 

across walkways, where they can create tripping hazards (See the Office of Compliance’s 

“Slips,Trips andFalls”FastFacts). Considerationcanalsobegiventothemeritsofinstalling 

modular furniture that provides multiple outlets at each workstation. Interconnected 

modular furniture units are energized by the building’s electrical supply through a single, 

large power cord, or “whip,” providing ample power to all served workstations. The OOC

noticed during recent biennial safety and health inspections that many offices of newly

elected House members have been outfitted with modular furniture. Many of the recipients

of the OOC’s Office Safety Awards during the 109th Congress were also equipped with

modular furniture. Figure 3: Daisy chain of power strips—One power 

strip is being used to energize two other power strips 

fast stats 

• All conductors and equipment must be approved by OSHA (29 CFR §1910.303(a)).

• OSHA’s electrical standards require that listed or labeled equipment be used or installed in accordance with any 

instructions included in the listing or labeling (29 CFR §1910.303(b)(2)).

• OSHA’s electrical standards require that outlet devices have an ampere current rating not less than the current 

load to be served (29 CFR §1910.304(b)(2)).

• The NFPA reports that wiring, switches, and outlets caused an annual average of 280 electrical fires, and $11 

million in direct office property damage between 1999-2002.

Peter Ames Eveleth 

General Counsel 

Rachel Berg Scherer 

Editor 

If you spot a safety hazard in your legislative branch 

workplace, contact the Office of Compliance to report it: 

Room LA 200, John Adams Building 

110 Second Street, SE 

Washington, DC 20540 

t/ 202-724-9250; tdd/ 202-426-1912; f/ 202-426-1913 

Recorded Information Line/ 202-724-9260 

www.compliance.gov 

The Office of Compliance advances safety, health,

and workplace rights in the U.S. Congress and the 

Legislative Branch. Established as an independent

agency by the Congressional Accountability Act of 

1995, the Office educates employees and employing 

offices about their rights and responsibilities under the 

Act, provides an impartial dispute resolution process,

and investigates and remedies violations of the Act. 

This information does not constitute advice or an official ruling of the Office of Compliance or the Board of Directors and is intended for educational 

purposes only. For further information, please refer to the Congressional Accountability Act (2 U.S.C 1301 et seq.) and the regulations issued by the 

Board, or you may contact the Office of Compliance.