Service entrance cable size for 100 amp and 200 amp service.

Asked Nov 1, 2008, 11:10 AM — **16 Answers**

I would like to know what size aluminum sec I would need for 100 or 200 amp service

stanfortyman · Nov 1, 2008, 01:52 PM

#2 for 100A
4/0 for 200A

brianbadbrian · Nov 2, 2011, 09:45 PM

100 amp #4cu or #2al

200 amp #2/0cu or #4/0al.. .

Try looking at the NEC for service entrance conductor ampacity before you answer stan.. .

tkrussell · Nov 3, 2011, 02:41 AM

And what exactly is incorrect about Stan's answer?

stanfortyman · Nov 3, 2011, 03:55 AM

Originally Posted by brianbadbrian

try looking at the the NEC for service entrance conductor ampacity before you answer stan . ..

Hmmm... I actually find this pretty funny. :D

donf · Nov 3, 2011, 05:24 AM

Brian,

Try reading the question before running off with the mouth.

The OP only asked for the sizes for Aluminum conductors. Stan gave the correct answer.

cre8tive31 · Apr 4, 2012, 07:48 PM

What seize wires do I need from the meter can to a transfer switch for a standby generator. And also what seize do I need from the transfer switch to the service panel going into conduits. How many singles

stanfortyman · Apr 5, 2012, 04:28 AM

Originally Posted by cre8tive31

What seize wires do I need from the meter can to a transfer switch for a standby generator. And also what seize do I need from the transfer switch to the service panel going into conduits. How many singles

All we know is you want to install a transfer switch.

What size service?
What size transfer switch?
What size generator?
What size conduits?
What are "singles"?

What is your location?

cre8tive31 · Apr 6, 2012, 02:40 AM

200A service.
200A automatic transfer switch with service disconnect.
20,000KW GE whole house generator.
1 1/2" or 2" PVC conduit depending on wire seize.
Single wires from meter can to transfer switch and from transfer switch to 200A service panel using PVC conduit.

Location.
Bloomfield CT.

stanfortyman · Apr 6, 2012, 12:14 PM

Very good. Thank you.

You'll need typical 4/0AL or 2/0CU, three conductors, from the meter to the transfer switch. You can downsize the neutral if you like. 2" is typical.

From the transfer switch to the panel you'll need four wires, using a dedicated equipment ground, this can be #4cu. 2" will work as well.
Remember, the main panel will now become a sub-panel, so all the grounds will need to be separated from the neutral bar and a dedicated ground bar installed, and the neutral bond removed.

From the generator to the transfer switch you'll need #4cu minimum, also running four wires. I'd do a separate 1" for the power and a 3/4" for the controls.

cre8tive31 · Apr 6, 2012, 03:53 PM

From the transfer switch to the generator.
I was thinking of running as follows:
3 single THHN #3
1 #6
2 #12
2 #18 or 1 twisted pair #18 (in a separate conduit)

Could I use 3 single THHN 3/O for meter can
And ( 4 single THHN 3/O going back to the panel or 3 THHN 3/O and a #6)

In a 2" conduit PVC

cre8tive31 · Apr 6, 2012, 04:14 PM

From the transfer switch to the generator.
I was thinking of running as follows:
3 single THHN #3
1 #6
2 #12
2 #18 or 1 twisted pair #18 (in a separate conduit)

Could I use 3 single THHN 3/O for meter can
And ( 4 single THHN 3/O going back to the panel or 3 THHN 3/O and a #6)

In a 2" conduit PVC

stanfortyman · Apr 7, 2012, 04:45 PM

Originally Posted by cre8tive31

From the transfer switch to the generator.
I was thinking of running as follows:
3 single THHN #3
1 #6
2 #12
2 #18 or 1 twisted pair #18 (in a separate conduit)

Could I use 3 single THHN 3/O for meter can
and ( 4 single THHN 3/O going back to the panel or 3 THHN 3/O and a #6)

in a 2" conduit PVC

The #3 and 3/0cu are overkill for residential, but you can if you like.
The four 3/0cu is WAY overkill IMO.

cre8tive31 · Apr 7, 2012, 08:09 PM

Thank you so kindly for all of your useful info.
Once again I thank you,stanfortyman.

cre8tive31 · Apr 7, 2012, 08:13 PM

Oh by the way the generator is about 100ft. Away from the transfer switch and the service panel and that's the reason for that seize wire.

shottsk2002 · Dec 17, 2013, 08:04 PM

Wouldn't the transfer switch be the sub panel since first point of entrance is still main panel?

hfcarson · Dec 18, 2013, 05:05 AM

Shottsk - would you call a transfer switch a panel?
And if it was?
Please, elaborate...

Service entrance cable size for 100 amp and 200 amp service.

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