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Stu27 09-05-2010 02:36 PM

Re-route dryer electric cable
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I'm looking for some advice on re-routing my dryer electrical cable (either lengthening the existing cable or abandoning the existing cable in place and running a new cable)

The house was built in 1984. The house has separate two attics (first floor and second floor). The 220V electric dryer is on the first floor. The dryer electrical cable was routed from the panel in the basement up a first floor wall, across the first floor attic, back into the living space by way of through the second floor master bathroom wall then immediately through the floor, proceeding below the second floor, and finally down the first floor laundry room wall to the dryer receptacle.
I am remodeling the master bathroom and the original dryer electrical cable that was routed into the corner had been hidden behind the cavity of the steel bathtub and the bathroom wall (see attached picture). It appears to have been routed in this manner for two reasons: (i) there was an builder option to have the laundry room on the second floor, thus the indirect routing to the dryer's current location would be a direct routing to an optional location on the second floor, and (ii) the cable was routed through the bathroom wall and back into the floor to avoid an engineered beam that prevented the cable from being routed from the first floor attic directly below the second floor subfloor.
I'm replacing the bathtub with a full shower and want to reclaim the full floor space for the shower pan.

The dryer is currently on a dedicated 30 amp circuit with the following cable:
"Alcan S Stabiloy Type SE Cable Style U Type XHHW CDRS 600 Volts 3 CDRS 8 AL (UL) 1984"
If I've deciphered the cable label correctly it's 3 conductor #8 aluminum wire (I did pull the panel cover and verify AL). The length of the run is about 70 feet from panel to receptacle. Was the #8 specified, instead of #10, due to the length of the run to reduce the voltage drop?

Anyway, after all that yappin'… I'm looking at two options:

Option 1.
Lengthening the cable by splicing it to add about 5-10 feet of new cable in the first floor attic. Splicing and lengthening the cable would allow me to re-route the existing cable from below the master bathroom subfloor, through the non-load bearing shower valve wall, and back into the first floor attic. My readings on this forum lead me to believe that splicing is an acceptable and safe method of extending the length of the dryer cable as long as the splices are contained in boxes and the boxes are accessible.

If I choose the splice option:
- What are the considerations for splicing #8 aluminum wire? (my experience is with #12 and #14 copper and wire nut connections)
- Are wire nuts acceptable for #8 connections on a dryer cable?
- Must the inserted wire be of the same material as the current wire (aluminum)? (HD didn't have #8 AL, but did have three and four conductor #8 CU. I assume I can get #8 AL at an electrical supply co).
- Is the attic splice option considered a remodel in that it would require an upgrade to four-wire cable?

Option 2.
Abandon the existing cable and run a new cable from the panel to the dryer receptacle. The basement is unfinished so I'd have full access, although I believe it would be easier / faster to splice the existing cable as describe in option 1.

I'd welcome any suggestions regarding alternatives to reclaim the bathroom floor space.

gregzoll 09-05-2010 02:38 PM

If the laundry is on the first floor, why not just pull new 10/3 for the dryer up through the wall from the basement to the first floor laundry? Would be a more logical reason.

Stu27 09-05-2010 05:20 PM

Yes, a new line is an option. I failed to note previously that I'd have to splice the two 14/2 lines in the photo also routed poorly. So at a min, I'm gonna be in the attic for those two, just trying to keep it simple by including the dryer line while I'm up there. However, if the dryer circuit is best served with a new line vs. splicing the old one I can that. Do y'all think a new dryer line is the best approach given there are three lines that need attention? If so, should I run the new line in Cu (the existing dryer and ac circuits are the only Al in the house)?

rjniles 09-05-2010 05:22 PM

That SE cable is Service Entrance cable and consists of 2 insulated aluminum conductors and a bare ground wire wrapped around the 2 insulated conductors and an outer sheath. While it can continue to be used for a dryer using a 3 conductor cord, it can not be changed, relocated or extended. It is 8 ga because aluminum has a lower amperacity than copper.

You need to run in a new 10-3 NM cable for this circuit and use a 4 wire cord on the dryer.

BTW, those cable coming thru the floor and going into the stud need to be protected if they are left open like that.

gregzoll 09-05-2010 05:24 PM

Pull new lines. As for Aluminum vs Copper, Copper should be ran. Only place that there should be Aluminum if a newer home, is the drop from the meter to the POCO.

brric 09-05-2010 05:48 PM


Originally Posted by gregzoll (Post 496387)
Pull new lines. As for Aluminum vs Copper, Copper should be ran. Only place that there should be Aluminum if a newer home, is the drop from the meter to the POCO.

That is an opinion and not a factual statement.

gregzoll 09-05-2010 07:56 PM

And please tell me why? You never see AL in newer homes for branch circuits, unless the contractor went on the cheap. AL devices rated for the use for AL needs to be used, but since majority of consumers out there do not know this, they would create a hazard. This has been discussed on this board over and over about the use in a home with AL.

brric 09-05-2010 08:02 PM

We use Al SE and SER all the time for ranges, electric furnaces and other large appliances as well as sub panels and it is perfectly safe when properly installed.

Stu27 09-05-2010 10:18 PM

1 Attachment(s)
Okay, the consensus is to pull a new dryer line rather than splice and extend the current line. Will do. And in the process I'll switch the line to copper. Thanks to rnjiles and gregzoll for focusing me back on doing it better instead of just okay.

I will properly protect the remaining 14-2 wires now that the tub will no longer provide that protection. I plan to re-route those wires under the subfloor and in the shower faucet wall to the right (see photo #2, blue line for 14-2 cable re-routing, red line indicates perimeter of new shower floor pan).

As for aluminum vs. copper, I don't see a reason not to switch to copper if I'm pulling a new line. Doesn't copper have a lower resistance than aluminum, so the same current should flow with less resistance in copper than in aluminum and therefore the copper wire should heat up less than an aluminum wire of the same size, correct? Given the more favorable material characteristics of copper for carrying current, wouldn't lower cost be the only reason to use aluminum over copper? I guess I can see the economies of scale for a builder to use aluminum. For me I'd think there would be a small material cost increase but significant performance benefits to using copper.

The new run will be about 60 feet and inside conditioned space. I recall reading that #10 is adequate for a 30 amp circuit (and rjniles confirmed that 10-3 NM cable is recommended with a dryer cord upgrade). Would the 60 foot cable run be a cause for going from 10 gauge wire to 8 gauge?

frenchelectrican 09-06-2010 12:39 AM

I just want to make it clear you can not extend the exsting SE cable at all the code do not allow to do that anymore it was change way back 1996 code cycle { I belive it was in effect way much before that with few area }

So you will have to run new 6.0mm˛ triplex NM cable { 10 -3 NM cable }

The 6.0mm˛ { #10 AWG } is perfect to use on dryer circuit and you will have to change from three wire cord to four wire cord and ditto with receptale as well.

The alum cable is little more bulkier due the restinace rating if you have to use the alum cable the size will be 10mm˛ { #8 AWG } but you will need SER cable due it is full 4 conductor cable and they are little bigger than 6.0mm˛ triplex.

It much eaiser to find the 6.0mm˛ triplex NM cable { 10-3 NM } than 10mm˛ triplex SER cable { 8-3 SER } but it is your call which way you want to do.


Stu27 09-06-2010 08:21 PM

I didn't realize the proposed mods to the SE cable were not permitted by code. Thanks for the clarification.

I re-routed the 14-2 and 12-2 cables today. I've forgotten how miserable an attic can be. I'm sure I'm 10 lbs lighter.

Picked up all of the materials to run a new dryer cable. 10-3 NM and new dryer cord and receptacle. All four wire. The basement will be a paradise compared to the attic work.

Thanks again to all for your time and positive feedback.

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