Generator plug types explained: 5-20, TT-30, L5-30, L14-30 and 14-50

A generator's control panel can look like a puzzle. Each outlet has a code like "L14-30R" printed next to it. Once you know how to read the code, you'll know exactly what it can power and which cord it takes.

How to read the code

These are NEMA codes, the US standard for plugs and outlets.

• The first number is the type. "5" is a normal 120 V outlet with a ground. "14" carries both 120 V and 240 V.
• The number after the dash is the amps. "30" means 30 amps.
• "L" at the start means it locks. You push the plug in, then twist it.
• "R" at the end means receptacle (the outlet). "P" means plug (the cord end). So a TT-30R outlet takes a TT-30P plug.

The six you'll see

Outlet	Volts	Amps	Max watts	Typical use	What it looks like
5-15R	120	15	1,800 W	Household wall outlet	Two flat parallel slots, one wider than the other, plus a round or U-shaped ground hole
5-20R	120	20	2,400 W	Standard outlets on most generators and power stations	Like a 5-15, but one slot is T-shaped, so it takes 15 A and 20 A plugs
TT-30R	120	30	3,600 W	30 amp RVs and travel trailers	Two slots angled in a V (each 45° from vertical) plus a round ground hole. Some have a center hole that isn't a contact
L5-30R	120	30	3,600 W	Some generators, boats, some RV cords	Three curved slots in a circle. Push in, then twist to lock
L14-30R	120/240	30	7,200 W	Home hookup through a transfer switch or interlock	Four curved slots in a circle. Push in, then twist to lock
14-50R	120/240	50	12,000 W	50 amp RVs, some big generators, EV charging	Four openings: three straight slots and a ground hole. Larger than a household outlet

Max watts are volts × amps. For loads that run for hours, plan on about 80% of that. A 30 A connector, for example, is rated for 24 A continuous.

Which generators have which?

From the makers' spec pages for models on our site:

• Small inverters (about 2,000 to 2,500 W): 5-20 outlets only, sometimes a TT-30. 120 V only.
• Mid-size inverters (about 4,000 to 5,000 W): 5-20 outlets plus a TT-30. Still 120 V only.
• Large open-frame generators (7,500 W and up): 5-20 outlets plus an L14-30. Some add a 14-50, and the DuroMax XP13000EH has an L5-30 as well.

An outlet's watts are a ceiling, not a promise. A 4,000 W generator with a TT-30 can't actually send 3,600 W through it if other outlets are busy. The generator's total running watts always win.

RV plugs: TT-30 vs 14-50

30 amp RVs use a TT-30. It's 120 V only. Don't confuse it with the old NEMA 10-30 dryer plug, which looks similar but is 240 V. The blade angles and size are different, so a plug that doesn't slide in easily is the wrong plug. Never force one.

50 amp RVs use a 14-50. It has two 120 V legs, for 240 V and up to 12,000 W. A generator with an L14-30 can feed a 50 amp RV through an adapter, but you're limited to 30 A. WEN's L14-30P to 14-50R adapter, for example, is rated 7,200 W. See generator cords: 30 amp vs 50 amp and how to connect a generator to an RV.

TT-30 vs L5-30

Both are 120 V and 30 A. The difference is shape. The TT-30 is a straight push-in plug. The L5-30 is a twist-lock. Adapters exist between them. WEN sells a TT-30P to L5-30R adapter rated 3,600 W.

For home backup: L14-30 or 14-50

To power house circuits, you need a 240 V outlet, so either the L14-30 or the 14-50. A licensed electrician installs a transfer switch or interlock and an inlet box on the outside wall. Then a cord runs from the generator's outlet to that inlet. See how to connect a generator to your house and 120 V vs 240 V.

Never make or use a cord with a plug on both ends to feed a wall or dryer outlet. That's called backfeeding. It can electrocute utility workers and start fires.

Cord tips

• Match the plug and the amps. A 30 A outlet needs a 30 A cord.
• Buy the cord for the outlet, not the other way around. Check the code on the panel before you order.
• Use outdoor-rated, heavy-duty cords. Check for cuts before every use.

Safety: Run it outdoors only, 20+ feet from the house, away from windows and doors. Read our carbon monoxide guide.