SER to MHF splice

[mikegt4]

I have been thinking of upgrading the electric in my detached garage. When I built it 20 years ago my electrical needs were satisfied with a 40A feed. I have been considering upgrading my air compressor to a 5 hp unit in the future and need to upgrade the electric feed size if I go that route. Needless to say the garage panel will have to be upgraded as well.

My main panel is 200A and I would go with the 2-2-2-4 MHF that seems to be the "go to" size on this forum. I need to go 50' through the basement and another 50' to the garage panel, underground in conduit. My basement "ceiling" is floor trusses (16" tall) but the HVAC ducts and plumbing pretty much block the path for any 2" conduit across the basement inside the trusses and I really don't want to run conduit under them. Therefore I am considering 2-2-2-4 SER from the main panel to where the feed exits the house, a SER to MHF splice in a junction box between the trusses just inside the foundation wall. The box would have the access panel facing down flush with the bottom of the trusses.

Since it's the weekend I can't check with the AHJ as to what code cycle they are on, usually it is one behind. What I am wondering is the size of the junction box that I would need and the best type of splice to use. Just doing research at this time but I would like to sleep at night again.

 

[PaulKTM350]

I did something close to this myself, I did mount a 12x12x6 plastic box on the outside of the house for the splice (Home Depot). The electrical experts said that MDF cable can NOT go inside the house, not 1" even! Use a cable splice to make up the junction. Such as:http://www.polarisconnectors.com/black.html
Paul

 

[acer66]

I am not 100% sure but I think MHF can be run inside a house if under ground or protected by running it inside a pipe etc..

 

[pattenp]

MHF can go inside the house but needs to be in conduit. URD is what can't go inside the house, has to be terminated outside.

 

[pattenp]

A 12 X 12 X 6 box should pass inspection if on 2" conduit. The box size is determined based on the conduit size and number of connections. Generally box is sized 6 times the conduit diameter. Split bolts or Splice/Reducers are the cheapest option for splicing.

 

[theoldwizard1]

Split bolts or Splice/Reducers are the cheapest option for splicing.

Because I am a paranoid kind of guy, I would use the special anti-corrosion "paste" for aluminum splices. Linerless splicing tape is great. Good old fashion HIGH QUALITY friction tape (3M 1755) is fine. 2 wraps in opposite directions for both.

 

[bjcouche]

Split bolts and splice reducers are the cheapest, but requires the installer to know how to properly tape up the connection with the proper rubber tape, etc. Without knowing an installers skills, I usually recommend power distribution blocks. That way there's no taping involved. Remember that if your box is metal you'll have to ground the box as well.
https://www.automationdirect.com/ad...,_UL_Recognized,_175A-760A_(PB_Series)/PB1012

Brian

 

[mikegt4]

Thanks everyone. It looks like the best way to go, hopefully this summer.