Running service wire in crawl space AND underground

[justinae]

Also is 2-2-2-4 Mobile Home Feeder not available in your area? It may be cheaper than buying single THHN/THWN wire. The MHF is already assembled with a white marked neutral and a green ground where as the THHN/THWN you need to mark at the terminations.

Can you run MHF in the conduit? My understanding is that I can run MHF all the way from panel to panel and direct bury in the ground but that there is a risk associated with unprotected cable. I'm not too worried about digging animals but am concerned about some trees that are rooting where my trench is.

 

[pattenp]

Just make sure the wire you get has the THHN plus THWN rating. The "W" means it's suited for wet locations. Most aluminum wire has what's called compacted conductors. The conduit fill rate it higher for conductors that are compacted. Example is 4 regular stranded #2's will fit in 1 1/4 PVC where as 5 compacted stranded #2's will fit in 1 1/4" PVC conduit.

 

[pattenp]

Can you run MHF in the conduit? My understanding is that I can run MHF all the way from panel to panel and direct bury in the ground but that there is a risk associated with unprotected cable. I'm not too worried about digging animals but am concerned about some trees that are rooting where my trench is.

Yes MHF can be run in conduit. MHF is rated for direct bury if you don't want to use conduit, but putting it in conduit is a smart thing. MHF has to be in conduit when run inside and it can be run inside because it is fire resistant rated.

 

[justinae]

OK, THHN with THWN rating and compacted for all stand alone wires.

Thanks, this is really helpful. Now to find the best place to get them. So far Home Despise seems to have the best price for 2-2-2-4 at $1.49/ft.

 

[justinae]

Yes MHF can be run in conduit. MHF is rated for direct bury if you don't want to use conduit, but putting it in conduit is a smart thing. MHF has to be in conduit when run inside and it can be run inside because it is fire resistant rated.

So what would be the advantage to MHF? If I could run it without conduit in the crawl space and walls then perhaps, but if I need conduit the whole way then SER w/ junction to individual seems easiest.

 

[pattenp]

There is no real advantage to MHF the whole way other than eliminating a splice, but then you have a lot more conduit to run in the house. MHF has to be in conduit when run inside of the house and garage. SER from the house panel to a junction box and then the MHF to the garage is your other option. Pick your poison.

 

[wyliesdiesels]

So what would be the advantage to MHF? If I could run it without conduit in the crawl space and walls then perhaps, but if I need conduit the whole way then SER w/ junction to individual seems easiest.

Except that MHF HAS to be run in conduit when inside a building! I'm not sure why this is cause its fire retardant! @pattenp ???

 

[pattenp]

Except that MHF HAS to be run in conduit when inside a building! I'm not sure why this is cause its fire retardant! @pattenp ???

MHF has to be in conduit because it is individual conductors and does not have an overall outer jacket. It falls under the same requirement as any single conductor run of needing to be in conduit. If MHF didn't have the fire resistant rating it couldn't be run inside the house even in conduit.

 

[wyliesdiesels]

There is no real advantage to MHF the whole way other than eliminating a splice, but then you have a lot more conduit to run in the house. MHF has to be in conduit when run inside of the house and garage. SER from the house panel to a junction box and then the MHF to the garage is your other option. Pick your poison.

What is the temp grade of MHF? I'm not fully versed on all the different cables out there and have never used this type. Also, the same with SER and SEU. I know they're service entrance cable but I have never run them. I realize this was gone into detail and debated on by you and someone else in another recent thread but I haven't had the time to catch up on all the comments in that thread!

Edit: I've ran SE cables before, just never looked to see if they were SER or SEU!

 

[justinae]

Very interesting. I think I'll go with individual wire instead of MHF for the short run as it might be easier to fish.

Again, very helpful.

 

[wyliesdiesels]

MHF has to be in conduit because it is individual conductors and does not have an overall outer jacket. It falls under the same requirement as any single conductor run of needing to be in conduit. If MHF didn't have the fire resistant rating it couldn't be run inside the house even in conduit.

Oh I c. That makes sense. So, this begs the question that if MHF is individual conductors, what's the difference between it and individual wire like THWN? Why is it specifically called MHF other than the obvious?

 

[wyliesdiesels]

Very interesting. I think I'll go with individual wire instead of MHF for the short run as it might be easier to fish.

Again, very helpful.

MHF IS individual wire so there wouldn't be a difference in pulling ease!

I tell ya! I learn something new almost every day!

 

[pattenp]

Oh I c. That makes sense. So, this begs the question that if MHF is individual conductors, what's the difference between it and individual wire like THWN? Why is it specifically called MHF other than the obvious?

To answer your other question about temp on the MHF. It is sized based on 75 degree.

Mobile Home Feeder is a Southwire product and it's their marketing name for the wire product. The main difference from it and individual THHN/THWN is it's an assembled cable and is rated for direct bury and the insulation is rated RHH/RHW-2/USE-2. Southwire's "SIMpull THHN" is a THHN/THWN-2 rated wire.

 

[pattenp]

OK, THHN with THWN rating and compacted for all stand alone wires.

Thanks, this is really helpful. Now to find the best place to get them. So far Home Despise seems to have the best price for 2-2-2-4 at $1.49/ft.

Beware some of the 2-2-2-4 Al wire HD sells is URD (Underground Residential Distribution) and is only rated as USE-2. Meaning it cannot be run inside, period. It's not fire resistant.

 

[Falcon67]

I ran the HD 2-2-2-4 inside and the inspector bought it off just fine. I'd have to look at the wire since I forget exactly what the specs were, but it carried all the proper ratings for that use. It runs 55' through an attic and 36' through 2" conduit. Fused at 70A. Inspected from one end to the other by the local.

 

[pattenp]

I ran the HD 2-2-2-4 inside and the inspector bought it off just fine. I'd have to look at the wire since I forget exactly what the specs were, but it carried all the proper ratings for that use. It runs 55' through an attic and 36' through 2" conduit. Fused at 70A. Inspected from one end to the other by the local.

The HD's in Texas probably carry Mobile Home Feeder since Texas is the Mobile Home capital of the US.

 

[justinae]

At the store now. The 2 2 2 4 wire says " Alcan s stabiloy aa-8030 Type se cable style r xhhw-2 600v 3 cdrs 2 awg (33.6mm2) 1 cdr 4 awg(21.2) sun-res (ul) 2012"

Is this the right one?

 

[pattenp]

At the store now. The 2 2 2 4 wire says " Alcan s stabiloy aa-8030 Type se cable style r xhhw-2 600v 3 cdrs 2 awg (33.6mm2) 1 cdr 4 awg(21.2) sun-res (ul) 2012"

Is this the right one?

It's the right cable for the inside. No conduit needed because it's SER.

This is it, right?

*

 

[justinae]

Yes. That is it. And I got triplex for the conduit run.

 

[pattenp]

Yes. That is it. And I got triplex for the conduit run.

Triplex??? That's a 3 conductor cable. You should have gotten a Quadruplex which is a 4 conductor cable.

Does this cable happen to have a bare conductor?

 

[justinae]

No. I bought a separate #4 for the ground.

 

[pattenp]

No. I bought a separate #4 for the ground.

Okay. I know what you got. It's Triplex UD. I was thinking Triplex Service Drop. You need to check the insulation markings. I believe it's only rated as USE-2 which means it can't be run inside at all because it's not fire resistant rated. It needs the XHHW or RHH or RHW-2 ratings. I hope I'm wrong.

What's the rating on the #4 ground you bought?

 

[Falcon67]

The HD's in Texas probably carry Mobile Home Feeder since Texas is the Mobile Home capital of the US.

Damn straight. Tornado Bait - Got to keep those tornadoes out of New Mexico. I must confess that at one time we owned a 28x40 on two acres - was a nice place. And damn cheap livin!

 

[wyliesdiesels]

To answer your other question about temp on the MHF. It is sized based on 75 degree.

Mobile Home Feeder is a Southwire product and it's their marketing name for the wire product. The main difference from it and individual THHN/THWN is it's an assembled cable and is rated for direct bury and the insulation is rated RHH/RHW-2/USE-2. Southwire's "SIMpull THHN" is a THHN/THWN-2 rated wire.

I thought u said earlier that MHF is individual conductors? I'm confused! Do u happen to have a pic?

 

[justinae]

http://www.homedepot.com/Electrical...Id=10053&langId=-1&storeId=10051#.UFFat6RSTUM

That's the triplex I got.

I've been thinking about how to transition from the LB into the garage and see I can get 1 1/4" flex. Then I started thinking that since my run from the junction box to the panel in the garage is only about 10' why not just do it all in flex. Any reason not to? I'll still need the LB but that's it I think. That also makes drilling through the stud easier.

Thanks.

 

[pattenp]

I thought u said earlier that MHF is individual conductors? I'm confused! Do u happen to have a pic?

It is considered individual conductors but is twisted into a cable. Because it doesn't have an outer sheath it is required to be in conduit when used inside.

 

[justinae]

This may seem like a dumb question, but couldn't I run the SER all the way to the junction and then simply strip off the outer sheathing in the part that runs in the conduit? Then no splicing and much smaller junction box.

I'm not planning to do that, but was just curious.

 

[pattenp]

http://www.homedepot.com/Electrical...Id=10053&langId=-1&storeId=10051#.UFFat6RSTUM

That's the triplex I got.

I've been thinking about how to transition from the LB into the garage and see I can get 1 1/4" flex. Then I started thinking that since my run from the junction box to the panel in the garage is only about 10' why not just do it all in flex. Any reason not to? I'll still need the LB but that's it I think. That also makes drilling through the stud easier.

Thanks.

I so hate to tell you this but the Triplex you bought is not allowed by code to be used inside of the garage. It is a URD and does not have a fire resistant rating and can only be used outdoors. If you look at the specs on the HD site you'll see that "Fire Retardant" is marked as "No" and "Indoors/outdoors" is marked "outdoors". You can use it but I just wanted you to know it would not pass code.

 

[justinae]

Even if it's running in conduit the whole way?

 

[Norcal]

This may seem like a dumb question, but couldn't I run the SER all the way to the junction and then simply strip off the outer sheathing in the part that runs in the conduit? Then no splicing and much smaller junction box.

I'm not planning to do that, but was just curious.

The wire in SER cable is not a recognized conductor outside of the sheathing which this also applies to NM cable, if you look there are no markings on the indv. conductors as to what they are.

 

[justinae]

The wire in SER cable is not a recognized conductor outside of the sheathing which this also applies to NM cable, if you look there are no markings on the indv. conductors as to what they are.

I figured it was something like that and that's why it isn't done but was curious anyway. It seems strange that there isn't a more straightforward way to wire a detached garage, but this way isn't too bad.

 

[wyliesdiesels]

Even if it's running in conduit the whole way?

Check out what pattenp said to me earlier on pg 3 about fire retardant and cable! Regardless of conduit use, cable run inside a building must be fire resistant!

 

[mrobins297aaa]

I so hate to tell you this but the Triplex you bought is not allowed by code to be used inside of the garage. It is a URD and does not have a fire resistant rating and can only be used outdoors. If you look at the specs on the HD site you'll see that "Fire Retardant" is marked as "No" and "Indoors/outdoors" is marked "outdoors". You can use it but I just wanted you to know it would not pass code.

other than its not to code whats the real risk here?

 

[pattenp]

This may seem like a dumb question, but couldn't I run the SER all the way to the junction and then simply strip off the outer sheathing in the part that runs in the conduit? Then no splicing and much smaller junction box.

I'm not planning to do that, but was just curious.

Just as Norcal said plus the fact the SER has an uninsulated ground and is not protected from moisture in the conduit so it will oxidize over time.

 

[wyliesdiesels]

It is considered individual conductors but is twisted into a cable. Because it doesn't have an outer sheath it is required to be in conduit when used inside.

Ok I see now. We don't have many MHs here so MHF is not something I've run across before!

 

[pattenp]

other than its not to code whats the real risk here?

Actually I'd say the risk is slim to none. Code is written to be on the absolute side of safety.

Read this for insulation types..... http://baen.tamu.edu/users/stark/AGSM325_files/Lecture/4a WiringVoltDrop Handout.325.pdf

 

[pattenp]

Ok I see now. We don't have many MHs here so MHF is not something I've run across before!

Oh.. come on now. I've seen lots of these in your area.

 

[justinae]

I have the wire in front of me. It says "Compact Stabiloy AL XLPE 600V USE-2 or RHH or RHW-2"

According to the chart you sent RHH and RHW are both fire retardant.

Am I missing something?

 

[justinae]

The rating on the number 4 ground is exactly the same.

 

[pattenp]

I have the wire in front of me. It says "Compact Stabiloy AL XLPE 600V USE-2 or RHH or RHW-2"

According to the chart you sent RHH and RHW are both fire retardant.

Am I missing something?

It's time to celebrate. You have the correct wire. The HD web link you posted was not the wire you purchased. It's 1:40AM, I'm going to bed. This has just tired me out.