Service and Sub panel feeders on a budget

[RD35]

Is there any reason, Code or otherwise, why I should not design a feeder system for a residence utilizing Aluminum Mobile Home Feeder cable in Sch 40 PVC that runs through the house from a 200A Service Breaker just inside the wall opposite the meter base to the MLO panel in the center of the home? The cable is compacted Aluminum with RHH, RHW-2, USE-2 rated insulation. Conduit will be suspended below the floor joists of the home and then run up into the bottom of the house panel. Terminations will utilize an anti-oxidation paste on the stripped ends of the compacted aluminum conductors and the lugs are CU/AL 75° rated. Size would be 4/0-4/0-2/0-4 for the 200A feeder.

Also, is there a code related reason, (or any other good reason) for why aluminum SER Cable is not available in 4/0-4/0-2/0-4 configuration?

Thanks

 

[electrofelon]

Is there any reason, Code or otherwise, why I should not design a feeder system for a residence utilizing Aluminum Mobile Home Feeder cable in Sch 40 PVC that runs through the house from a 200A Service Breaker just inside the wall opposite the meter base to the MLO panel in the center of the home? The cable is compacted Aluminum with RHH, RHW-2, USE-2 rated insulation. Conduit will be suspended below the floor joists of the home and then run up into the bottom of the house panel. Terminations will utilize an anti-oxidation paste on the stripped ends of the compacted aluminum conductors and the lugs are CU/AL 75° rated. Size would be 4/0-4/0-2/0-4 for the 200A feeder.

No there is no reason not to use that cable, however I would tend to use SER over pipe and wire in such a situation. Also, I typically would not strive to put the panel in the middle of a house if it could go on an exterior wall.

Also, is there a code related reason, (or any other good reason) for why aluminum SER Cable is not available in 4/0-4/0-2/0-4 configuration?

Thanks

perhaps it doesnt have a reduced neutral so it can be used for three phase? Or maybe for use in single phase 120/208 systems where the neutral is less likely to be reduced?

 

[RD35]

Yes I agree! Not having a reduced neutral in those cases is warranted. I just don't understand why the cable manufacturers make reduced neutral feeder cables without a sheath and do not offer reduced neutral feeder cables in an outer sheath covering. I suspect it's in the code somewhere, but I cannot locate it. Still looking!

 

[petersonra]

Is there any reason, Code or otherwise, why I should not design a feeder system for a residence utilizing Aluminum Mobile Home Feeder cable in Sch 40 PVC that runs through the house from a 200A Service Breaker just inside the wall opposite the meter base to the MLO panel in the center of the home? The cable is compacted Aluminum with RHH, RHW-2, USE-2 rated insulation. Conduit will be suspended below the floor joists of the home and then run up into the bottom of the house panel. Terminations will utilize an anti-oxidation paste on the stripped ends of the compacted aluminum conductors and the lugs are CU/AL 75° rated. Size would be 4/0-4/0-2/0-4 for the 200A feeder.

Also, is there a code related reason, (or any other good reason) for why aluminum SER Cable is not available in 4/0-4/0-2/0-4 configuration?

Thanks

Is Aluminum Mobile Home Feeder cable a chapter 3 wiring method?

 

[ActionDave]

Is Aluminum Mobile Home Feeder cable a chapter 3 wiring method?

Yes. I don't know if it officially called Mobile Home Feeder but has always been called that my whole life because it has an insulated EGC and is both direct bury rated and can be run indoors as well.

 

[electrofelon]

Is Aluminum Mobile Home Feeder cable a chapter 3 wiring method?

Yes. I don't know if it officially called Mobile Home Feeder but has always been called that my whole life because it has an insulated EGC and is both direct bury rated and can be run indoors as well.

Around here, the difference between MHF and 4 wire URD is the MHF has a reduced neutral. The MHF always seems to be USE-2/RHH-2. Sometimes 4 wire URD is just USE-2 without the RHH-2. I just googled it and its looks like southwire's MHF is available with both full neutral and reduced, so these are rather loose terms.

 

[RD35]

That's what I have found as well. The Mobile Home Feeder cable is almost identical to standard URD Aluminum except for a couple things. It has a neutral AND a ground wire where URD usually only has the neutral for use as a feed from the utility transformer to the service disconnect. The MHF is designed to be run from the Mobile home's outdoor pedestal mounted service disconnect into the home to feed the house panel. It's insulation is multi-rated as USE-2, RHH, and RHW-2 which makes it legal to run inside the building in conduit.
My main reason for starting this thread is to see if any of you folks with lots of experience would know of a reason why I should not design a sub-panel feeder inside a building (or residence) that consists of Aluminum MHF cable with the reduced neutral run in PVC 40 conduit. This seems to be the most inexpensive alternative available. Aluminum SER Cable costs more and does not have a reduced neutral option for some reason.

 

[electrofelon]

That's what I have found as well. The Mobile Home Feeder cable is almost identical to standard URD Aluminum except for a couple things. It has a neutral AND a ground wire where URD usually only has the neutral for use as a feed from the utility transformer to the service disconnect. The MHF is designed to be run from the Mobile home's outdoor pedestal mounted service disconnect into the home to feed the house panel. It's insulation is multi-rated as USE-2, RHH, and RHW-2 which makes it legal to run inside the building in conduit.
My main reason for starting this thread is to see if any of you folks with lots of experience would know of a reason why I should not design a sub-panel feeder inside a building (or residence) that consists of Aluminum MHF cable with the reduced neutral run in PVC 40 conduit. This seems to be the most inexpensive alternative available. Aluminum SER Cable costs more and does not have a reduced neutral option for some reason.

no nothing wrong with doing it that way, although I dont see how you will save money over SER after buying the pipe, not to mention the labor.

 

[kwired]

Yes I agree! Not having a reduced neutral in those cases is warranted. I just don't understand why the cable manufacturers make reduced neutral feeder cables without a sheath and do not offer reduced neutral feeder cables in an outer sheath covering. I suspect it's in the code somewhere, but I cannot locate it. Still looking!

Demand thing, it may or may not be something the manufacturer makes, but if people aren't buying it, or enough of it, supply house isn't going to stock it.

That's what I have found as well. The Mobile Home Feeder cable is almost identical to standard URD Aluminum except for a couple things. It has a neutral AND a ground wire where URD usually only has the neutral for use as a feed from the utility transformer to the service disconnect. The MHF is designed to be run from the Mobile home's outdoor pedestal mounted service disconnect into the home to feed the house panel. It's insulation is multi-rated as USE-2, RHH, and RHW-2 which makes it legal to run inside the building in conduit.
My main reason for starting this thread is to see if any of you folks with lots of experience would know of a reason why I should not design a sub-panel feeder inside a building (or residence) that consists of Aluminum MHF cable with the reduced neutral run in PVC 40 conduit. This seems to be the most inexpensive alternative available. Aluminum SER Cable costs more and does not have a reduced neutral option for some reason.

It is just a convenient pre- assembled set of conductors, each that already has an individual or even multiple ratings. Must be installed in same manner as any individual conductor with same ratings marked on it, in a raceway is acceptable, direct bury is acceptable if one of those ratings is USE.

 

[Jon456]

Since you're planning to run conduit, wouldn't it be cheaper to pull in individual compact aluminum wires instead of aluminum MHF cable? I haven't looked at pricing of MHF, so I have no idea. But it seems to me that cable would be more expensive due to the additional material and manufacturing steps.

Or is it that you happen to already have the MHF on hand?

 

[electrofelon]

Since you're planning to run conduit, wouldn't it be cheaper to pull in individual compact aluminum wires instead of aluminum MHF cable? I haven't looked at pricing of MHF, so I have no idea. But it seems to me that cable would be more expensive due to the additional material and manufacturing steps.

Or is it that you happen to already have the MHF on hand?

These aluminum assemblies are typically cheaper than individual conductors.

 

[kwired]

Since you're planning to run conduit, wouldn't it be cheaper to pull in individual compact aluminum wires instead of aluminum MHF cable? I haven't looked at pricing of MHF, so I have no idea. But it seems to me that cable would be more expensive due to the additional material and manufacturing steps.

Or is it that you happen to already have the MHF on hand?

Not necessarily. I don't run into MHF all that often, but have run plenty of dual rated URD in the past and is often less cost than using individual XHHW conductors. But you also want simple pulls with only a couple elbows in the run and no pull boxes or conduit bodies in the run or it will create some difficulty, exception is a pull box or conduit body say outside and short length to inside and that is the end of the run, there you can untwist and install like individual conductors through that last short section.

With individual conductors you also need to set up multiple reels or measure off individual conductors, with the MHF or URD you don't do this, you just pull them as is. For a short run, often it is simply convenience or maybe even just whatever you have available. For a long run it may be less cost to use the multiconductor assembly in some cases.

 

[Jon456]

Thanks Kwired for the detailed and informative reply! Thanks to electrofelon too.

 

[RD35]

Thanks to all for a great discussion. Better than half of the feeder run to the subpanel is required to be under a concrete garage floor (no other good way to get from here-to-there) ...hence the conduit is now a requirement for that portion anyway. And without a reduced neutral using XHHW (even if I strip off the outer sheath for pulling) would cause me to want to upsize the conduit to 2-1/2...which is way more expensive. I have an inside line on some new Southwire MHF aluminum cable that makes this even more economically feasible. So, since there seems to be no NEC code prohibition on it, I'll check with Mr. Inspector (AHJ) to be sure he is good with it! Thanks again...very helpful!