Picking Power Cables for Your Portable Generator Need

When using a portable generator one of issues is how to use the power output. As discussed in How Many Watts Do I Actually Get to Use with My Portable Generator you have restrictions on actually use of the output.

The key to using the power effectively is in matching the power cable (extension cord) to the output. Manufactures develop these cables to provide limited line losses by sizing the wire and lengths to meet a given output.

Do not assume you can put two rated cables together to extend your length. Length and wire size are tied together to give you minimal line loss. Two smaller wire sizes although rated at a specific amperage will not be big enough and you can see significant voltage loss.

You do have the option to build your own cables. The important aspect is to use rated connectors and then match a length of wire that has appropriate wire size to minimize voltage losses. When determining the wire sizes we recommend Paige Wire Calc or Wikipedia for  wire gauges  that go into this in detail needed to size your wire.

The following information provides you with general information and links to specific cables that will provide you with what you need to get your appliances and tools connected.

Power Cord and Receptacle Labeling

Cords are related to the plug and receptacle labels.

Ex: 5-20R, L14-30P

The most common types found on the USA market are 5, L5, L14, 14, TT, CS. We will address those here.

In general, labeling is with a receptacle/plug type. If the label has only a number it is a slotted and easily loosened plug/receptacle combination. If it has an L it is a twist lock and is inserted and turned to prevent accidental pulling out of the plug.

The second number is the amperage rating. 20 for 20 amps, 30 for 30 amps, etc. The last Letter is R for receptacle and P for plug.

Cords will typically just indicate the type and amperage as they have both a plug and receptacle end.For more on labeling see our post on Plugs and Receptacles.

5-15 and the 5-20 Cords – 120V

The 5-15R is the common household 3 prong receptacle in North America. It has the vertical slot and rounded pin at the bottom with one slot being longer than the other. It is rated for 15 amps of use.

The 5-20R (20 amp rating) is the most used outlet in most portable generators. It is the three prong outlet like the 5-15R but with a T slot on one side see the graphic below to see the differences. some 5-20R do not use the T-slot. Make sure you are reviewing your configuration for appropriate use.

The 5-20R is utilized and matched with circuit breakers from around 13 amps up to the full 20 amp rating.

NEMA 5 Receptacles and Plug

NEMA 5 Receptacles and Plug

Although you can plug 15 amp rated extension cords into the T-slot receptacle be aware that it is always better to match ratings to ensure minimal line losses. This is especially true with longer cords as you don’t want the voltage losses to affect your use at the other end.

The following power extension cords are recommended based on different lengths

15 Amp Ratings

StarTech.com PAC1016 6-Feet Power Cord Extension – NEMA 5-15R to NEMA 5-15P

StarTech.com PAC10120 – 20-Feet Power Cord Extension – NEMA 5-15R to NEMA 5-15P

20 Amp Rating

Yellow Jacket 2991 20-Amp Generator Cord with T-Blade 5-20 Lighted Ends, 50-Feet

Coleman Cable 026188802 20-Amp Generator Cord 5-20P to 5-20R, Lighted, 50-Feet

L5-20 and L5-30 Cords – 120V

Many of the higher end portable generators have a L5-30R outlet. This is handy as it allows you to connect a L5-30P to the generator and use a multiple type 5 outlet at the other end allowing you to use 2 or 3 tools or appliances that use less than the total rated amps or 3600 watts.

NEMA L5 125 V

NEMA L5 120 V

In the really powerhouse generator models at 14kW and above it is not unusual to find two outlets for the L5 type. The L5-30 is the most commonly supplied outlet for portable generators.

Here are a few good power cord options for L5 outlet.


Coleman Cable 01915 3-Feet Generator Power Cord Adapter, 10/3 Splitter Y Adapter, L5-30P to (2) Lighted 5-20R

Reliance Controls AP31RV 30 Amp L5-30 to RV Generator Power Adapter Plug

L5 – 20 amp

Coleman Cable 01911 25-Feet 10/3 Generator Power Cord with L5-20P Plug and 3-Outlets

Conntek RUL520PR-050 50-Feet 10/3 20-Amp 125-volt L5-20 Anti-Weather, Oils, Acids and Chemicals Rubber Locking Extension Cord

L5 – 30 Amp

10 Foot L5-30P to L5-30R Extension Power Cord – Rated 30A/125V

Coleman Cable 01912 25-Feet 10/3 Generator Power Cord with L5-30P Plug and 3-Outlets

Conntek 20571 Generator Extension Cord 25-Foot 10/3 30 Amp 3 Prong NEMA L5-30 Eextension Cord

L14-20 and L14-30 Cords – 120/240V

The L14 is a four prong system which allows two 120V circuits to be used to provide the 240V output. Therefore you have two hot leads, one neutral, and one ground.

NEMA L14 Receptacles

NEMA L14 Receptacles

The L14-20R is used on generators that are under 5000W, The L14-30R is found on more generators and may show up on wattage below 5000W, but more often on generators above 5kW.

The 20 and 30 amp receptacles are different based on the prong location and twist. This is to help insure proper rating matching.

The L14 is most often used to connect your portable generator to your transfer switch to supply power to your dwelling. It can be used to extend to a distribution outlet to power a number of appliances and tools from a central location.

Here are some of the top sellers and quality cords:

L14-20 Power Cords

Reliance Controls PC2010 10-Foot 20 Amp L14-20 Generator Power Cord For Up To 5,000 Watt Generators

Conntek 20591 Generator Extension Cord 25-Foot 10/4 20 Amp 125/250 Volt 4 Prong Extension Cord

Conntek 1.5-Feet, 20-Amp L14-20P 125/250-Volt to (4) 15/20-Amp Female Connector, 4 Prong Generator Locking Extension Cord

L14-20P to L14-20R Extension Power Cord, 50 Foot – 20A, 125/250V, 12/4 AWG

L14-30 Power Cords

L14-30 Generator Power Cord – 50 Foot, 10/4 Wire, 30 Amps, 125/250V

Conntek 20601-020 20-Feet, 30-Amp 125/250-Volt L14-30P/R , 4 Prong Transfer Switch Cord/Generator Extension Cord

Reliance Controls PC3010 10-Feet 30-Amp L14-30 Generator Power Cord for up to 7500-Watt Generators

Coleman Cable 01934 3-Feet Generator Power Cord Adapter, 10/4 Splitter Y Adapter, L14-30P to (2) 10/3 Lighted 5-20R

14-50 Cords – 120/240V



The 14-50R appears with the larger units, it is not a locking outlet primarily due to the expense at this rating in making the receptacle.

If you have a unit equipped with this size outlet you will need to ensure you clip it and protect it against pull out.

 There are a couple of cables to fit this outlet.

Camco 55195 50 AMP 30′ Extension Cord with PowerGrip Handle

Generac 6389 25-Foot 50-Amp Generator Cord with NEMA 1450 Male End and CS6364 Female Locking End

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10-30R & TT Receptacles

Both the L6 and L10 is for 240V in a three prong configuration. These are not found that often in the US market. The one thing that does occur is the TT and NEMA 10 are sometimes confused. They are not interchangeable. The NEMA 10-30 is typically used for electric dryers.

TT20 and 10-30R

TT20 and 10-30R

TT stands for travel trailer and is a special designation used for many RV hook ups. You’ll find some generators with this configuration especially designed to be used with your recreational vehicle.

Here are a few connectors and cords available for this hook up.

NEMA 10-30

Forney 57601 Male Electrical Plug, Crowfoot Type, Nema 10-30 10-50

HUBBELL HBL9337C AC Plug NEMA 10-30 Male

Conntek RL-40105 6-Feet 3-Wire 30-Amp 250-volt Dryer Cord

Leviton 5207 125/250V Flush Mount Receptacle

TT Cord Connectors for Travel Trailer Options

Camco 55197 30 AMP 50′ RV PowerGrip Extension Cord

Camco 55185 RV PowerGrip 30M/50F AMP 18″ Dogbone Electrical Adapter with Handles 3750W/125V

Conntek RV 30 Amp Extension Cable Cord with Glowing Strip (White, 25-Feet)

DuroMax L14 – 10/3 30 to 30 Amp RV Adapter for all standard 30A RV’s

Conntek RV 30 Amp Male Plug To 30 Amp Locking Connector Cable with Glowing Strip (White, 25-Feet)

Leviton 7313 30 Amp, 125 Volt, NEMA Tt-30R, 2P, 3W, Flush Mounting Receptacle, Straight Blade, Industrial Grade, Grounding, For Recreational Vehicles, Side Wired, Steel Strap, Black

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cs6364The CS6364 is a locking receptacle in the 50 amp range. It is supplied on certain generators and is not considered a standard NEMA plug. Most power cords available are from the 14-50 male to the female CS6364. You can build your own cord with the individual plug and receptacle ends. Be sure to get a wire size and length for the 50 amp rating.

Here are some CS cord choices.

Generac 6330 10-Foot 50-Amp Generator Cord with NEMA 1450 Male and CS6364 Female Locking End

Conntek 1450SS2-25 25-Foot Temporary Power Cord, 50-Amp 125/250-Volt, NEMA 14-50P Generator Plug to CS6364 Locking Connector


Reliance Controls LL550C 50 Amp Generator Power Cord Connector For Up To 12,500 Watt Generators

Reliance Controls LL550P 50 Amp Generator Power Cord Plug For Up To 12,500 Watt Generators

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There are any number of choices to power cord selection. You need to match to your specific generator output.

Our recommendation is to determine the longest potential need and use a rated cord for that length. Hooking to cords together for a rated load can contribute to voltage loss over the long length. A larger wire size is required to minimize these losses.

Getting short lengths can be more economical and should be considered in specific situations where you are hooking up to your house or other service.

To understand the restrictions on circuit breakers and plugs check out tips and buyer guide section for knowledge to help you get a generator for your needs.

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