I want to move a dryer in a mobile home. Can the wire from the existing outlet be pulled down and spliced in a j-box with wire running to new location under the home?

Yes you can. Make sure junction box is covered and accessible.

Thanks for your response.
Can I run romex or MC? The code seems to be saying I need to run EMT (pipe) but I'm not sure of my interpretation.

Thanks for your response.
Can I run romex or MC? The code seems to be saying I need to run EMT (pipe) but I'm not sure of my interpretation.

UNDER the home use NMT and pull wire or UF if you can get it in the gage needed. I'd probably use NMT.