THNN vs SER for subpanel

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techmavin

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Hi

Connecting a Main panel to a 125 A subpanel 10 feet away in basement. Is it preferred to use 4 (2 live + neutral + Ground) AWG #1 THNN wire or SER wire (In NJ I could only get Aluminum SER wire)?
THNN would need to be in conduit. I am planning to use Greenfield (Flex metal Conduit) for THNN. Electrician friend of mine said he would use SER.
I don't like using Aluminum. Any thoughts on which one is better and pros and cons of both?
 
techmavin said:
Hi

Connecting a Main panel to a 125 A subpanel 10 feet away in basement. Is it preferred to use 4 (2 live + neutral + Ground) AWG #1 THNN wire or SER wire (In NJ I could only get Aluminum SER wire)?
THNN would need to be in conduit. I am planning to use Greenfield (Flex metal Conduit) for THNN. Electrician friend of mine said he would use SER.
I don't like using Aluminum. Any thoughts on which one is better and pros and cons of both?
Click to expand...
Aluminum is totally fine, that said SER has taken such a huge jump in price that copper and Greenfield will be about the same price..... Of course it only 10 ft long price difference isn't going to be much of a factor. I would say just whatever is quickest and easiest. Is this surface mount or through framing?
 
for me it would depend on the physical arrangement of the basement. Copper is nice because it's smaller and might, might go into the panel's terminals without a special lug.
 
There is absolutely nothing wrong with the use of aluminum conductors, improperly installed copper conductors can do just as much damage as improperly installed aluminum alloy conductors.
 
What size aluminum SER? And how does that compare in price to the #1 THHN copper with the FMC?
 
Price it both ways, but the SER cable should still be cheaper and less labor intensive.

Even if it needs physical protection, sleeving it has looser rules than conduit-ing.
 
#2 copper is good for 115 amps but can be protected at 125.

Running conductor in raceway does give you option of using metallic raceway as the EGC therefore one less conductor and along with that potentially can be smaller raceway to contain everything as well.
 
electrofelon said:
Aluminum is totally fine, that said SER has taken such a huge jump in price that copper and Greenfield will be about the same price..... Of course it only 10 ft long price difference isn't going to be much of a factor. I would say just whatever is quickest and easiest. Is this surface mount or through framing?
Click to expand...
Surface mount
 
techmavin said:
Hi

Connecting a Main panel to a 125 A subpanel 10 feet away in basement. Is it preferred to use 4 (2 live + neutral + Ground) AWG #1 THNN wire or SER wire (In NJ I could only get Aluminum SER wire)?
THNN would need to be in conduit. I am planning to use Greenfield (Flex metal Conduit) for THNN. Electrician friend of mine said he would use SER.
I don't like using Aluminum. Any thoughts on which one is better and pros and cons of both?
Click to expand...
I tell people that insist on Cu vs Al, look at what the POCO uses to your service!
 
Little Bill said:
I tell people that insist on Cu vs Al, look at what the POCO uses to your service!
Click to expand...
Around here is is a little mixture of both. Not much for longer runs of copper, but a majority of POCO provided risers up pole from a meter socket contain copper conductors. Most longer overhead or underground conductors however are aluminum.
 
kwired said:
Around here is is a little mixture of both. Not much for longer runs of copper, but a majority of POCO provided risers up pole from a meter socket contain copper conductors. Most longer overhead or underground conductors however are aluminum.
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I don't think our POCOs even know what copper looks like! Also, anything from the meter up a pole is electrician/customer supplied and installed.
 
Little Bill said:
I don't think our POCOs even know what copper looks like! Also, anything from the meter up a pole is electrician/customer supplied and installed.
Click to expand...
The rural POCO's here usually will put a meter and disconnect (or a meter/disconnect combo unit) depending on service voltage, capacity and some other factors on a pole. Usually customer is charged for it but POCO will generally maintain it if needed over time. Customer or their contractor is responsible for load side conductors beyond that point.

There are some circumstances where customer or contractor is to provide underground raceway and POCO will pull conductors through it. Most those cases they are pulling aluminum conductors. Occasionally contractor provides raceway and POCO pulls MV cable through it to a padmount transformer. Some this varies from one POCO to the next though.
 
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