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Old 12-01-2012, 12:18 PM   #1
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30 Amp Generator - 50 Amp Power Inlet


I apologize if this has been answered elsewhere, but I didn't find it in my search. If it's already been answered, a point in the correct location would really be appreciated. Here goes....

I have wired into my home a generator panel with a manual lockout. I have installed a 50-amp back feed breaker (may change to 30-amp) and the appropriate 50-amp wire (6/3). I have not yet purchased an inlet box, but a friend gave me an extra 30-amp one he had (new in the box).

My initial thought was to install a 50-amp inlet box on the house (in case we end up with a larger generator later). But I'm thinking that we may initially use a smaller generator (>=5000 watts) - which I believe would come with a 30-amp NEMA plug. I called an online distributor of generators and accessories to ask about a power cord with a 30-amp plug on generator side and with a 50-amp plug on the house side (inlet box).

I was told I could NOT purchase this because of the different NEMA plugs required for the different amp ratings. I'm not too clear regarding the different NEMA specifications, but I'd like put the higher rated inlet box on the house for potential future use (if needed). The house is 4200 square feet. And though I don't think we'd require 50-amp in a power outage, if we were to find the 30-amp generator was insufficient, I wanted to be able to simply purchase a larger generator and power cable without having to change out the inlet box.

I don't see why it would not work, but the local electrical distributors know nothing of this stuff (at least the ones I've reached out to) and I wasn't sure the online company was correct in their answer. I understand I would not want to overrate the wire from the inlet box to the panel which is why I went with the 6/3 (rated for 50-amp). If I can find it, I'd be looking for maybe a 25-foot cord so it's a little ways from the house while running.

Are there any issues with using a 30-amp generator and plugging into a 50-amp inlet box other than the (NEMA) connection plugs? If no issues, how or where can I find such a power cord?

Any comments or questions appreciated.


Last edited by 1BadBoy; 12-01-2012 at 12:22 PM.
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Old 12-01-2012, 02:19 PM   #2
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30 Amp Generator - 50 Amp Power Inlet


Just change the female plug on the end of the cord.
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Old 12-01-2012, 10:16 PM   #3
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30 Amp Generator - 50 Amp Power Inlet


Provided that the generator has its own built in breaker (here, 30 amps) it does not matter if you plug it into an electrical system via a larger (here, 50 amp) backfed breaker (and fat enough Romex cable for the larger future amperage).

As mentioned before, just make up a cable with the appropriate plug and (female) receptacle to fit the generator receptacle and house inlet respectively.

Caution: Be sure you wire up the plug and receptacle pins correctly (neutral to neutral, etc.). In another recent thread on this forum someone fried his generator probably due to incorrect connections.
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Last edited by AllanJ; 12-01-2012 at 10:23 PM.
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Old 12-02-2012, 10:28 AM   #4
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30 Amp Generator - 50 Amp Power Inlet


Thanks for the suggestions. I'm thinking of changing the inside breaker to 30-amp for now since my initial generator will most likely be a smaller size. I'll probably keep the 50-amp available to swap out just in case.

As for wiring my own cable, I could probably do that (and correctly), but was also hoping to find someplace where I could simply get the correct cable ordered/made.

Any companies out there that could/would do this?
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Old 12-02-2012, 10:33 AM   #5
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30 Amp Generator - 50 Amp Power Inlet


Quote:
Originally Posted by joecaption View Post
Just change the female plug on the end of the cord.
http://www.leadsdirect.co.uk/images/...igurations.gif
Thanks for the image link! I notice it says "Non-Locking" - is there a similar image for "Locking" or are they the same? Sorry, this is still a learning experience for me at this point.
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Old 12-02-2012, 11:08 AM   #6
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30 Amp Generator - 50 Amp Power Inlet


Quote:
Originally Posted by 1BadBoy View Post
Thanks for the suggestions. I'm thinking of changing the inside breaker to 30-amp for now since my initial generator will most likely be a smaller size. I'll probably keep the 50-amp available to swap out just in case.

As for wiring my own cable, I could probably do that (and correctly), but was also hoping to find someplace where I could simply get the correct cable ordered/made.

Any companies out there that could/would do this?
If your generator is putting out 240V, ignore the following.

It's fairly common for RVs to have a cord with a 50A 120V plug, and the campground to only have 30A 120V sockets. And the reverse is also true... an RV with a 30A 120V plug and a campsite with a 50A 120V socket.

So camping / RV stores likely will have adapter cords to go either direction. One such is Camping World.
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Old 12-09-2012, 11:23 AM   #7
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30 Amp Generator - 50 Amp Power Inlet


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Originally Posted by Dave632 View Post
If your generator is putting out 240V, ignore the following.

It's fairly common for RVs to have a cord with a 50A 120V plug, and the campground to only have 30A 120V sockets. And the reverse is also true... an RV with a 30A 120V plug and a campsite with a 50A 120V socket.

So camping / RV stores likely will have adapter cords to go either direction. One such is Camping World.
I'm looking to install a 240v generator so that I don't lose 1/2 of panel. I will shut down all breakers prior to switch over to back feed breaker, but I want to choose breakers from either side of panel. I spoke to an electrician recently who said that they make up cables like that from time to time while doing marine generator connections, so he said it's no problem to make a custom cable if one cannot be found.

I'd like to find one pre-made (or custom made) if I can, but I'll fall back to make my own if I don't find anything else suitable.

Last edited by 1BadBoy; 12-09-2012 at 11:54 AM.
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Old 12-09-2012, 03:50 PM   #8
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30 Amp Generator - 50 Amp Power Inlet


You can buy a 30amp cord (25ft) at HD for about $70. The 50 amp (25 ft) cord is about $190.
I would hook it up with the 30 amp inlet you have and get the 30 amp cord.
If and when you get a bigger generator with a 50 amp output, you change the inlet box and buy a 50 amp cord.

Or better yet, for that type of output, look at a pad mount, hard wired standby generator that runs on NG\LPG.

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