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wiring inlet box to panel

hello, i want to install an inlet box for my generator on the outside of my house,i have everything i need except i dont know what kind of wire to get to go from the inlet box to the elecrical panel inside the basement. i will be using the interlock kit for the gen .it  has  a 30 amp plug. i need to know what size  wire i should use for this.i also need to get  a breaker for the panel ,it needs 2 spaces,if anyone has done this setup before please chime in for me

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Posted 2012-02-12T00:38:27+0000  by shuggy shuggy

Hello shuggy,


Welcome to the community, lets talk about your inlet box.


I agree with you, it sounds like you have everything except for your wire and breaker to hook it all up. The inlet box is great for generator installations and provides a good receptacle for your plug. Shown below, it  isn't the Interlock brand, but it works just the same.

Reliance 30 Amp Power Inlet Box

Since you are dealing with 30 amp wire, and depending if it is a short (no more than 100 ft. length) run, you can use a 10 gauge wire.


This gauge wire is rated for 30 amps, and if it requires an additional  load wire, I would recommend using 10-3 NM w/ground if it is being used in conduit or the wire can be installed entirely indoors. Most local codes (and common sense) dictate that if you run the wire to the inlet box and it is outside, you will need to have it in conduit so that it can be protected from the elements along with anyone that is near or at it.


I say use the NM (non-metallic) version instead of the outdoor UF (underground-feed) 10-3 w/ground, since it is going to be in conduit anyway, and the indoor NM version will be protected and easier to run this way. Plus, if you ever had to add or change out the wiring, it is easy to remove and replace. You only have to run conduit with the wires in where it is exposed to the outside of your house.

10-3 NM-B Wire 50 ft..png

It is your choice whether you want to use flexible or sturdier PVC conduit. Below are some fittings and the conduit that is more inexpensive to use, the standard PVC type, and it still works great for going into the inlet box.

0.5 Inch PVC conduit and fittings 

If your generator requires a double pole (in laymans terms known as a '220V') breaker, simply refer to the inside of your breaker panel in your basement and it will give you the exact brand of panel. Some circuit breakers can and will fit other brands of breakers, but to elminate guess work, look at the panel label first to get the right double-pole 30 amp breaker for your generator.


And last but most certainly not least, if you are ever unsure in these steps or need additional information like your local codes, consulting a certified and licensed local electrican is always the best choice to make.


I hope this has helped you out and please let us know if you have any further information.




Posted 2012-02-13T16:37:27+0000  by Joseph_HD_ATL

Hello, Don't forget the generator transfer switch that is required between your generator and the panel.   This is not only a code violation but could be dangerous for the linemen working on the lines.  There are cheaper ones to choose but this one is the easiest to in stall.  Most of them install just like a sub-panel. 


transfer switch.jpg  





Posted 2012-02-16T16:39:06+0000  by Stukas

A frequently overlooked and infrequently mentioned alternative to a transfer switch is installing an Interlock Kit in your load center.  The kit insures that the main breaker is in the off position before the breaker for the Generator inlet (back-fed breaker) can be put in to the on position.  Conversely it insures that the breaker for the Generator inlet is in the off position before the main breaker can be put in the on position.




I recommend only using a kit manufactured by the same company as your load center.  Some examples:


Properly installed this little kit allows you to back-fed your load center and still be safe.

Posted 2012-11-14T02:40:48+0000  by gtbarsi
I'm going to go with the interlock kit.

When wiring the 10-3 to the panel, the two hot leads wil go to the 2 pole 30 amp breaker.

How about the neutral and ground. Do they both need to be connected to the panel? Can they both go to to either the neutral or ground bus if the buses are connected/boned together.

If there are no more openings left on the bus, is it okay to double up where a single white or ground are connected to the buses?

Or do I need a a ground bar kit and ifso how is that connected if there is little or no room on the buses?
Posted 2012-11-21T02:52:57+0000  by Wayfarersun
NM cannot be placed inside conduit. It's a violation.
Posted 2012-11-21T04:38:55+0000  by jdsmith
No need to address this here. I created a separate post for these questions under "how is generator 10-3 wire and backfeed breaker connected to panel under an interlock kit setup"
Posted 2012-11-21T13:02:39+0000  by Wayfarersun

Hey Wayfarersun,


I already answered your question as you requested on the stand alone post you authored, if you can't find it, you can click on this link to review it. 


Best of luck to your project, and keep us updated on your progress.



Posted 2012-11-26T22:28:01+0000  by Joseph_HD_ATL

Hey jdsmith,


Thanks for joining us here on the community!


I have heard that putting Non-Metallic 'Romex' cable through conduit isn't code sometimes, but it does depend on things like if it will be inspected from what I heard.


But then again, I'm not an electrician.


You can use THHN grade cable in 10 gauge through conduit. The only type we carry is in stranded, not solid cable. 


Thanks for clarifying that for us, and please feel free to join us on more discussions here on the community.




Posted 2012-11-26T22:36:39+0000  by Joseph_HD_ATL

You can not run nm wire in a conduit unless you want to have a code violation.

Posted 2014-01-30T00:18:23+0000  by Kruzer
Did not see the other post about NM and conduit but how about giving advice that doesn't violate NEC.
Posted 2014-01-30T00:21:41+0000  by Kruzer
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