Why is underground wire cheaper than residential of same gauge?

I need to run power to my shed and side yard patio. On a 30A circuit and the run is about 150' total. The difference in cost for 10/2 orange and 10/2 grey (underground) is nearly $100. I would rather use the cheaper underground but I don't understand the reasoning for the underground being cheaper than the orange?

 

Search the web. That question gets asked a lot so your not the only one wondering. Quickly skimming I saw a few different reasons, none really relate to the cost to actually manufacture the cable.

 

What you rather use when it comes to the grey underground vs. the orange is that the orange type (nm-b) is not to be used underground. So there is no choice between the two.

 

What does code say about using underground cable above ground?

 

There are many uses not permitted for UF cable but none of them really pertains to general use. You can use UF cable anywhere you can use Romex. It is just quite a bit more difficult to work with.

 

Going to a detached shed you will need 4 wires. I would put a sub panel in the shed so you can run a few circuits from there in the shed.

As far as the patio - Is any of it covered. What will you be using there that requires power? You may want a sub panel there also. 4 wires to the patio also if you use a sub panel. I don't know how elabroate your patio is in the way of what you will be powering' fridge, oven etc.

Are you sure 30amps will be enough? Did you figure any type of load calculation of what you plan to power in both locations as to whether the 30amps will be enough?

Also, you may have to compensate for voltage drop with a 150 foot run. Have you considered that? If not do a few searches for "voltage drop". You may have to run a larger gauge wire/s to compensate for the voltage drop so be sure you have read up on it before you lay the lines.

 

You can use only 3 wires if you only want 120-volt loads. If it was me, I would run 4 wires.

 

Cost diff is kind of screwy at this point ever since the pandemic.
Your main concern though is that you can't use10/2orange (Romex) outdoors anyway even in conduit.
Only options are UF and THWN individual conductors in conduit.

Question: Why are you considering 2 wire plus ground instead of 3 wire plus ground?
What is it that you plan on powering.

150 foot run is long. voltage drop to consider so you may have to go higher than 10 gauge to 8 gauge depending on what you plan on powering.

You can run to the shed to a sub panel and then to the patio from the shed to another sub panel.
Don't know the layout of either so further suggestions are hard to give you.

Maybe if you can draw something out so we can see what you want to do and what you want to power.