Trailer in driveway question

[Nasicus]

If i wanted to hook up my trailer in my driveway to power temporarily,

The 30 amp 120 v receptacle and breaker with 10 awg wire should be sufficient for feeding this correct? (240.4)

This is still considered a branch circuit, because it is a cord plug in or will there be feeder calculations.

The trailer has its own panel inside having a main and individual breakers for each circuit, but i dont think thats relevant to my previous question, this would all be fed from a 30a receptacle


Thanks

 

[Buck Parrish]

As a general rule for overcurrent protection is to select an OCPD that protects based on ampacities 310.15. How ever we don't know what will be utilizing the power. Heat? AC? Power tools ?

 

[Nasicus]

It has a mini fridge, a heat/ac combo as far as the largest items for ampacity, besides a few receptacles and lights. There is a 30 to 50 amp adapter that comes with it.

but what i am concerned with is the conductor that feeds the receptacle it plugs into

So if i have this correct, i should be sizing my ocpd on 210.20,my non continuous load + 125% of my continuous,
the tipping point for for having to upsize the breaker and conductor is if we went beyond 26.25A continuous,
with a 35a wire in 310.15 in the 75 degree column 26.25 x 125% is 35

There should be no heat derating or bundling calculations because it would be 10/2, in a mild climate.

Also is there a code reference if a heat/ac combo is considered a continuous load, i would just assume it was for this calculation but im curious what the reference would be.

Thank you so much!

 

[Dennis Alwon]

You cannot use the 75C column for #10 as 240.4(D) won't allow it. 30 amp max

 

[Dennis Alwon]

10/2 nm must also be used at 60C.... see the asterisks at the end of the Table in 310

 

[Nasicus]

Thank you so my total would come to 22.5A correct? to use a 30a ocpd

 

[Dennis Alwon]

If your total non continuous load plus your continuous load was greater than 30 then you need more than 30 amps. IMO, 30 amps is probably fine.

 

[kwired]

It has a mini fridge, a heat/ac combo as far as the largest items for ampacity, besides a few receptacles and lights. There is a 30 to 50 amp adapter that comes with it.

but what i am concerned with is the conductor that feeds the receptacle it plugs into

So if i have this correct, i should be sizing my ocpd on 210.20,my non continuous load + 125% of my continuous,
the tipping point for for having to upsize the breaker and conductor is if we went beyond 26.25A continuous,
with a 35a wire in 310.15 in the 75 degree column 26.25 x 125% is 35

There should be no heat derating or bundling calculations because it would be 10/2, in a mild climate.

Also is there a code reference if a heat/ac combo is considered a continuous load, i would just assume it was for this calculation but im curious what the reference would be.

Thank you so much!

The receptacle you are plugging into is (presumably) protected by a 30 amp OCPD and is presumably supplied with at least 30 amp conductors. You will trip that device if you draw too much current for too long, nothing is in much danger of overheating. Inconvenience can happen if it trips.

 

[Nasicus]

Yes, it is protected from a 30A breaker with 10Awg conductors.

I was just curious about it, because the trailer has its own panel, i wanted to make sure there were no feeder calculations i was stepping on, only if it were hard wired i believe the conductors would be considered feeders, between the service panel and the sub panel (one inside the trailer).

But because it is a temporary plug in thing this would not require anything but for the receptacle its plugging into to be sized and protected properly

If i have all of my information correct, i will use Article 220 calulations to size my OCPD with 3va per sqft for lighting, 180va per receptacle outlet, + the fridge and ac/heater combo.

My Ocpd should be sized 125% continuous load + non continuous, to not overload breaker

The conductors were sized on the 60 degree column which is required for nm, and also the requirement for being on atleast 10awg on article 240

Basically if its pulling alot of amps i might want to upsize the breaker and conductor

Thank you, i appreciate your guys input i have been thinking about this for a while

 

[junkhound]

For practicality of yu trailer feed, you can ignore temperature rating concerns if your 10 AWG is laying out on the ground. The temperature rating are based on conductors being in an enclosed area.

 

[Little Bill]

If this is an RV, you don't need any load calculations. You just need to run at least #10 conductors from a 30A breaker and install an RV receptacle. You're way overthinking this. Worse case, you trip the 30A breaker.

 

[suemarkp]

Does this trailer have a 30A or a 50A plug (you said you have an adapter...). Most I've seen have a main breaker that will match its cord, 30 or 50 amps. After that, you don't need to do any load calcs for a trailer -- the manufacturer should have done that. RVs don't do load calculations like anything else. Article 551.42 describes what size power source you need based on number of circuits in the trailer.

 

[LarryFine]

Does this trailer have a 30A or a 50A plug (you said you have an adapter...).

To me, that doesn't matter, as the branch circuit's OCPD will protect all.

 

[kwired]

Does this trailer have a 30A or a 50A plug (you said you have an adapter...). Most I've seen have a main breaker that will match its cord, 30 or 50 amps. After that, you don't need to do any load calcs for a trailer -- the manufacturer should have done that. RVs don't do load calculations like anything else. Article 551.42 describes what size power source you need based on number of circuits in the trailer.

Hasn't made it clear if this is an RV or not either.

 

[kwired]

Yes, it is protected from a 30A breaker with 10Awg conductors.

I was just curious about it, because the trailer has its own panel, i wanted to make sure there were no feeder calculations i was stepping on, only if it were hard wired i believe the conductors would be considered feeders, between the service panel and the sub panel (one inside the trailer).

But because it is a temporary plug in thing this would not require anything but for the receptacle its plugging into to be sized and protected properly

If i have all of my information correct, i will use Article 220 calulations to size my OCPD with 3va per sqft for lighting, 180va per receptacle outlet, + the fridge and ac/heater combo.

My Ocpd should be sized 125% continuous load + non continuous, to not overload breaker

The conductors were sized on the 60 degree column which is required for nm, and also the requirement for being on atleast 10awg on article 240

Basically if its pulling alot of amps i might want to upsize the breaker and conductor

Thank you, i appreciate your guys input i have been thinking about this for a while

Branch circuit - "The circuit conductors between the final overcurrent device protecting the circuit and the outlet(s)."

In your application the 30 amp supply circuit is not a branch circuit IMO. Yes there is a receptacle in the middle somewhere, but there is no loads connected directly to this portion of the circuit and there is "final overcurrent devices" further downstream.

Now find a situation where you plug an individual load into that same receptacle and it becomes branch circuit for that application.

Same thing if you had a 50 amp (14-50 receptacle) plug and trailer with it's own panel inside it is a feeder, plug in a range or other individual appliance and it is a branch circuit.

It can be either depending on usage.

 

[ramsy]

You cannot use the 75C column for #10 as 240.4(D) won't allow it. 30 amp max

Excellent find, much simpler than trying to find all code sections that say the same thing.

Current carrying conductors?

Where in the code does it actually specify the number of current carrying conductors per raceway? The general rule of thumb I’ve always been taught is 9, but where can I find the literature?

forums.mikeholt.com

 

[ggunn]

Do you plan to power the trailer with a gender bender adapter that you will make for yourself? If so, pay close attention to the hot and neutral positions on the plugs. A friend of mine bought a trailer that was handyman wired with a homemade adapter that resulted in a hot/neutral swap when it was plugged into an outlet in his house. Neutral was tied to ground as well, and ground was connected to the trailer chassis.

Everything seemed to work fine; the first indication he got that there was a problem was when he ran cable TV to the trailer. He accidentally touched the cable shield to an aluminum windowframe in the trailer which arced and blew the breaker. I'm glad that's how he found out there was something wrong and not by someone getting hurt.