# 20 vs. 30 amp plug - transfer switch/generator

• posted on November 10, 2012, 2:47 pm
About to pickup a 5000ish watt generator, but I am very confused on what transfer switch to get. I know I have to get a switch rated for 5000 watts, but how do I match up the transfer switch with the generator.
Since most of the generators say "One 120 volt locking plug" I am not sure if the plugs are going to match up.
I am looking at http://www.reliancecontrols.com/ProductDetail.aspx?20216A Reliance 6 circuit to power just my oil furnace, oil hot water, refrigerator, and maybe one room of outlets. I assume 20 amp transfer switch will do the job with 5000 watts, but when I look at the transfer switch pictures I can't tell if the Plug is 20 or 30 amp.
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<%-name%>
• posted on November 10, 2012, 4:03 pm

You tell by looking at the specs of the transfer switch. It says power inlet NEMA L14-20. NEMA is a standard and the numbers after it tell the exect type of plug or receptical. They should look like thease:
http://www.bing.com/images/search?q=nema+l14-20&qpvt=nema+l14-20&FORM=IGRE #
You have a 20 amp plug. All you have to do is match the NEMA numbers and the last leter will tell if it is a Plug or Receptical.
I think you did make a typo and it should be 240 volt locking plug insteaad of 120 volts.
Many of the small gen sets have one locking 240 volt and pair of 120 volt recepticals.
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<%-name%>
• posted on November 10, 2012, 4:38 pm
wrote:

Yes, something isn't right. I've never seen a generator with a locking 120V receptacle, and they sure don't have plugs. More common and probably what he's looking at is one 240V receptacle and two or more 120V ones.
For transfer switch he needs one rated at 30A or above. 240V x 30A = 7200 watts.
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<%-name%>
• posted on November 10, 2012, 5:36 pm
Since I haven't bought either of these yet, it seems most 5000 watt generators come with a 30AMP locking plug. I assume if I get the Reliance unit that has a 30AMP plug (30216A) it will work with a generator like that.
I guess my question should have been do I have to match the generator to the transfer switch plug, which I assume you are saying is YES. It just means I can't select a generator with a 20AMP locking plug.
On Saturday, November 10, 2012 11:38:59 AM UTC-5, snipped-for-privacy@optonline.net wrote:

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<%-name%>
• posted on November 10, 2012, 6:04 pm

Generators don't have plugs. They have RECEPTACLES that you put a plug from an extension cord into. The Reliance transfer switch doesn't really have a plug either. It has an inlet, which is like a plug, but with protection around it so you can't get to the pins when it's being plugged in or disconnected.
You would use a 30 amp extension cord with ends that fit the generator and reliance switch.

From a practical perspective, that is what you want to do if you choose that particular transfer switch.
Are you sure you want or need that type of transfer switch for \$300? What kind of panel do you have? There are lockout slides from Interlockit available for many panels. Also, if it's a relatively new panel, the panel manufacturers have replacement cover panels that have a lockout built in. With either of those an additional double pole breaker, and an inlet you can power whatever you want in the house, not just the 6 circuits the Reliance panel gives you. And for less cost. And a lot less re-wiring.

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<%-name%>
• posted on November 10, 2012, 6:36 pm
I have a GE PowerMax Gold 200AMP Load Center. There is an interlock kit available for it that would probably cost \$200. I really don't need more than 6 circuits. And I think if I took away from the video it is only about an hours work. 2 wires to ground/neutral, pull off 6 circuit wires and wirelock them and connect 6 wires to the circuits. Am I missing something here, is this a bigger job than they are letting on?
On Saturday, November 10, 2012 1:04:46 PM UTC-5, snipped-for-privacy@optonline.net wrote:

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<%-name%>
• posted on November 10, 2012, 9:59 pm

It would seem to me it's a bigger job than freeing up a double pole breaker spot at the top of the panel, installing a breaker and an inlet. And doesn't that generator transfer switch with 6 circuits cost \$300?
Interlock kit \$200 Breaker \$15 Inlet \$40
For \$255 you have a solution that will then power not just 6 circuits, but selectively, anything you want in the whole house. Think about it. You manage any larger loads, turning them on selectively, disable any unneccesary ones, like washing machine, disposal, etc. Then you can leave on ALL the other breakers. Use what lights you need, selectively when you need them. If you need something from a closet, flip on the closet light switch. Need something from the garage, flip on the garge light. With the 6 circuit approach, all you have are those 6 circuits to work with. If that closet light or garage light are not on one of those, you're out of luck.
I'm not saying that the transfer subpanel is a big deal to install. Just that IMO the other approach is actually a bit easier and you get so much more, for less money.
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<%-name%>
• posted on November 11, 2012, 12:41 pm
noname wrote:

Yes, it's a significantly bigger job - compared to an interlock.
1. You've got to attach the transfer switch to the wall (somehow). 2. The transfer switch you're contemplating is for INDOOR use. You have two options: a. Buy a weather-proof box to house the sucker on the outside, or b. Punch holes in the wall for the wiring 3. It's possible your distribution panel is inside. Even so, you'll have to punch a hole in the wall and mount the receptacle for the generator's output, again on the outside. 4. No matter how or where you mount the transfer switch, dollars-to-donuts the wires will be too short, necessitating splices. 5. Count on a couple of trips to the hardware store for clamps, tie-downs, wire-nuts, wall anchors, odd screws, conduit, strangely shaped parts that have confusing names, and the like.
As to the advantages of an interlock: 1. No rewiring, of any kind, is required. 2. Mounting of anything is confined to the receptacle from the generator.
As a practical matter, with only six circuits monitored out of ten or more, you may have choose: TV and lights in the bedroom or TV in the den, light in the kitchen or washing machine. It will be moderately difficult, in times of emergency, to swap things around. This difficulty is NOT the case with an interlock.
Regarding the cost of an interlock, I agree the price is obscene. The interlock itself is (usually) a flat piece of metal of a particular shape and designed to engage both the main power switch and a double breaker serving as input from the generator. Now if you are immoral - some say a thief - you could buy the interlock from, say, Grainger, and, without even opening the package, trace the shape on a small sheet of 1/16" aluminum. Cut it out. Drill a couple of holes. Done.
Then, and here's where the dodgy part comes in, return the original, unopened interlock to your vendor for a full refund.
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<%-name%>
• posted on November 11, 2012, 1:08 pm

It would seem to me you have that same issues with the interlock on the existing panel approach as well. Any need to penetrate walls would be due to choice of where the INLET is located, which either approach uses. One reasonable alternative in either case is to have the inlet near the panel and just use an extension cord to go from there to the generator outdoors using a window, door, etc.

Again, no difference here that I see versus the panel interlock approach. And per above, no necessity to go through walls with either.

Agree. You'd have to splice those 6 circuits that are moved over. To be fair in the comparison, you'd probably also have to splice a couple of circuits if you go the panel interlock approach. You have to put a new double pole breaker at the top of the panel. Those spots are almost always full, requiring those circuits to be moved to a new breaker location, typically at the bottom. If the wires aren't long enough, you have to splice. I guess you could instead replace some breakers with half size ones, if available.

As far as I can tell, per above, that often isn't true.

+1
They could do that if inspection is not an issue, they don't care about having a panel that has been modified, not concerned about future home inspection at sale time, etc. That DIY interlock is not UL listed. But then apparently the ones from Interlockit are also not UL listed, though they are tested to UL. If it's going to need to pass inspection, then a panel cover from the manufacturer is the only way I know to be sure to be 100% compliant. If planning on using an Interlockit, I'd ask the inspector about the Interlockit before installing.
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<%-name%>
• posted on November 12, 2012, 12:01 pm
snipped-for-privacy@optonline.net wrote:

Could be true. In my case, the distribution panel is outside and the receptacle for the generator is attached to the distribution box. There are no additional holes in the wall required.

I see your point, although it wasn't true in my case. In any event, two splices, max, for an interlock beats the other option.

Well, it was in my case - except for attaching the receptacle.

First, if the inspector doesn't like your home-made interlock, it's trivial to remove it.
Second, do you have a lazer printer that can print on transparent labels?* Can you find a UL logo on the web? If your moral compass points to somewhere other than north, and you've created a home-brew interlock switch ...
---------- * When I traveled a great deal, I had a way of fighting back when the airlines jerked me around. I used the above set-up to print the following on clear address labels.
Warning! DISPOSE OF CONDOMS PROPERLY Do not flush. FAA 76-123a FAR 126.44
I kept a few in my wallet to add to the other wall stickers in the lavatory. Sort of my personal "Kilroy was here!" posting.
I reveled in wondering what some passengers would think, whether they would ask the flight attendant what the proper disposal method was, or, even, how one COULD use a condom on an airplane.
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<%-name%>
• posted on November 10, 2012, 7:52 pm
Ralph Mowery wrote:

5KW is 20.8A per leg. I'd recommend going one size larger on the transfer switch so you can accommodate the generators full rated capacity. It also will accommodate a larger generator should you upgrade in the future. The transfer switch needs to be rated for a minimum of your generator capacity, but it can readily be rated for higher without issues and it's code compliant.
Personally I recommend an approved generator interlock kit that fits your panel, they're cheaper, require no additional space, easy to install and more flexible than the small transfer sub panels. An interlock kit, a suitable breaker for the panel and wiring to a generator inlet box is all you need.
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<%-name%>
• posted on November 10, 2012, 9:48 pm

A 30 Amp switch will accomodate the full rated capacity. At 5KW, you never have more than 20.8A flowing in any conductor.
It also will accommodate a larger generator should you upgrade

Yes, I agree with that completely. I don't understand why anyone would prefer another subpanel for the generator with 6 circuits, when they can use the main panel and selectively power whatever they please. The only reasons I could see were if the original panel had no way to accomodate the additional breaker or if an interlock panel cover or kit was not available.
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<%-name%>
• posted on November 10, 2012, 10:05 pm
wrote:

After posting above, I read John's post. I was thinking the transfer switch was 30A, but as John pointed out. it's only 20. So, it;s just a wee bit under rated compared to the generator. I think we are all on the same page. He should have at least a 30 amp connection. And I'm with you guys in that if it were me, I'd do it with a panel interlock device, breaker and inlet.

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<%-name%>
• posted on November 10, 2012, 9:42 pm
About to pickup a 5000ish watt generator, but I am very confused on what transfer switch to get. I know I have to get a switch rated for 5000 watts, but how do I match up the transfer switch with the generator.
Since most of the generators say "One 120 volt locking plug" I am not sure if the plugs are going to match up.
I am looking at http://www.reliancecontrols.com/ProductDetail.aspx?20216A Reliance 6 circuit to power just my oil furnace, oil hot water, refrigerator, and maybe one room of outlets. I assume 20 amp transfer switch will do the job with 5000 watts, but when I look at the transfer switch pictures I can't tell if the Plug is 20 or 30 amp.
*That transfer switch has a 20 amp inlet (L14-20) which is a little small but may work for the few isolated circuits that you want. It does not include an inlet box for the flanged inlet so you would need to buy that separately. I think for long term you would be better off with an L14-30 inlet.
I am a big fan of the Interlock kit at http://www.interlockkit.com Using one of these you can safely power your entire circuit breaker panel. You would need the appropriate Interlock kit, a generator inlet box with the flanged inlet, a two pole circuit breaker with a holddown clip, and a cord. If your generator only has an L14-20 receptacle you can make your own cord with an L14-20 plug and an L14-30 female cord connector to connect to the inlet box.
Here's the link for GE: http://www.interlockkit.com/genelecmain01.htm
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<%-name%>
• posted on November 11, 2012, 4:45 pm

Nice - simple, relatively low cost and effective.
Thanks, John.
Tomsic