Posted: 11/28/2007 8:32:58 AM EDT
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I'm finally going to get off my ass and get a manual transfer switch installed. I have a troy bilt portable generator (link here ) that produces 5550 running watts and 8500 surge watts. It has a 220/240 outlet (NEMA# L14-30R 30 Amp) that I will run into a outdoor covered input outlet (need to find or make a cable for that). My primary goal is to have power to run my basement furnace, some lights, refrig and other critical appliances as needed. I can manage the load by switching in and out different circuits. I also have seen transfer switches or panels with analog or LED meters and that seems like a good idea. Current house wiring has 2 panels in my basement due to the number of total cir cuts I have. I'll take some pics and post if that will help. the smaller panel holds most of the circuits that I think we will need (planned it that way when we built house), but I need to do one final check to see what is running on what circuit and make sure I understand exactly which ones need to be linked to a switch or moved to a transfer panel. The smaller panel currently has 14 20 amp circuits, one 30 amp for bedroom level A/C unit (nice to have, but not critical) and 2 50 amp circuits for large first floor A/C and electric range (not going to use them). I've done some searching online and esp looked at the Reliance Controls Corp site (link) . One idea is to get a transfer panel since it could just replace the smaller panel and eliminate a 3rd box (transfer switch). and I get the impression I can have more than the 10-12 circuits that most transfer switches limit you to. I know that ultimately your limited by the load on the generator, but the option to leave non-essential circuits switched off would be nice and only use when needed. Thoughts, opinion, experiences, brand/model suggestions? The electrician is coming by tomorrow to discuss, but he told me on the phone to do my research and find what I think I want and we will work it out. Good guy. |
| Sounds like you should just go with a manual transfer switch between the main and the subpanel. One thing to consider is whether you plan on getting old in that house. As you get older the little things in life are nice.... like a generator and transfer switch that works automaically. |
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I'm an electrician, and around 2K installed a LOT of transfer switch/subpanels in houses. Typically we'd run an 8/3 w/ground outside to where the genny was, and hook up the subpanel right next to, or as close as we could get to the main panel. Most of what we dealt with was Square-D then, and they make a great little pivot switch, so when you turn on the backup, it disconnects the subpanel breaker at the same time. (They have to be next to each other in the subpanel.) You just take the circuits you want to stay on (minimum lighting, furnace, refrigerator, waterpump etc.) and run them into the subpanel, taking them out of the main panel. You do not have to take the neutrals and grounds with them, just the circuits, as the subpanel is fed like a normal subpanel would be until you flip the breakers. All you are doing is disconnecting the subpanel from the regular source of power. When power comes back on, you just turn off the genny, flip the subpanel breakers back to their normal position and you are set. With the physical disconnect there is no way you can backfeed the main panel as one turns off the other - one breaker goes to the Genny the other goes to a second 'main' breaker in the panel. With the switch, only one can be energized at once, so even if the main panel becomes energized, you are still cut-off from it. FWIW, they make prebuilt genny subpanels with fuses that are a really good idea, but We did a lot this way - GE makes the same sort of switch - it bolts in and hooks to both breakers. Think teeter-totter and you get the idea. One goes up, (on) the other goes down. (off) ETA: The key is knowing what your genny will handle and not overload it. You might not be able to run the subpanel because it may not (probably doesn't) have the circuits in it you need - ie: water pump, furnace, fridge. You (or your electrician) needs to identify which circuit the fridge is on for example, and make sure THAT gets into the genny panel. I HAVE backfed an entire panel with just two breakers acting as a transfer switch, but you have to watch your consumption or you will kick the breakers. |
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Northern tool has a good selection. This'll give you some ideas... www.northerntool.com/webapp/wcs/stores/servlet/category_6970_36+968+280092 |
well, i'm already 45 years old. lol Yes, that would be my ulitmate goal, but the $5k or so for that is out of reach for now. |
So am I. But the real question is that the house you will be in when you are retirement age or are you hoping to have a different house by then. You might see if you could go with a transfer switch that can upgraded once you get a gennie capable of remote start. Just trying to get you thinking.... give you more choices.... I have put in many systems and a few years later people want more and better systems. That is a waste of money doing some things twice. |
Automatic transfer systems can be expensive - I've put them in - last one for a new fire station we did a couple years ago. Very complex piece of electronics. Remember, it's more to go wrong. If you are so decrepit in your old age that you can't flip a breaker and go to the barn to push a button to start a generator, then you won't be able to gas up the genny either. I'm 46 myself, and I do think about this kind of stuff, but I plan on splitting wood until I'm ninety. At some point we will all need help - so you send the young'uns out in the snowstorm to start the generator!  However, thinking about upgrading later is a good point - I've had customers who wished they had listened to me about running a hot tub circuit or something similiar while the house was being built - but 6 months later they decide they want one, and it costs 3x as much and takes twice as much work, including cutting sheetrock. Thinking ahead really makes sense, and I have seen automatic transfer switches that were fairly inexpensive...OTOH I've also replaced a few of them, so you get what you pay for. I'd rather not be dependent on electronics and shunts trip circuits myself - K.I.S.S. applies here IMO. If you can find an automatic start unit, the start circuit will probably be LV so you can't run it in the same conduit, but you could zip tie it to the outside, or even run a separate conduit or liquidtite if you want. If you panel is outside the house, an auto-start circuit will be really nice in bad weather, and the genny panel can usually be backed up to the panel on the inside of the house/garage to make it easy in bad weather. Generally they aren't 3R packages, so you'd probably have to do that anyway. Good luck to you. ETA: I didn't notice what you said about most of the circuits you need being in the subpanel already - if that's the case, you could just move whatever other circuits you need (like pump if you have one, or furnace, freezer, etc.) into the subpanel, and use the entire subpanel as your genny panel. You just need to add a two-pole breaker and the lock-out switch I described right next to the main breaker in the subpanel. |
Yes, I think 80% of the circuits I want/need are already in the sub panel. Its connected to the main panel by a circuit breaking in the main panel (they are right next to each other). I'm no electrician, but I can tell the sub panel gets its power via that breaker, so if you isolate the breaker/subpanel..then no issue with backfeed, right? Why not do the switch your talking about or replace the subpanel chasies with one of the panel based transfer switches/tranfer panels? Like this one for example? link |
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Well, it's your choice. You can pay an electrician to add a breaker and a cut-out or buy an entire new panel as per the link with 'interlinked breakers' which is exactly what I was talking about, and pay him to put THAT in. You are now talking about a service change to change the subpanel, while just putting a second breaker in your subpanel will take much less work. MUCH less labor, much less money. The run to the generator will have to be done no matter what you do - but why replace something that doesn't need replacing on top of that? All that panel has that's special is the two main breakers linked together as I explained, one from one source (the main panel) and one from the auxiliary source (in this case the genny) It's the same thing, but more expensive than how I described it. When you flip one, the other disconnects. It's a physical connection, and very positive. The only question is, how much room do you have in your subpanel for additional circuits? (the 15% you may want to move onto the gen) You have a nice generator by the sounds of it, but altogether at 120v that's 45.8 amps running at 5500 watts. It can peak higher, but really, you have to look at it as a 50amp source...which is pretty damn good. I think you said the output recept was only a 30amp though - I'd ask your electrician what he thinks about what the generator can supply realistically. My boss in CO turned everything on in his house one time for giggles, including electric stove and amprobed his main - the house was drawing 33 or 34 amps, total. Water heaters pumps, electric heat and ovens are the biggest draws, which is why they are usually 240v. (less amperage). Remember, you can probably use thin breakers and quads, depending on the existing panel to add the circuits you need. $12-15 per twin breaker as opposed to whatever they want for that gear. Panels generally aren't expensive, but I bet that one you linked to is. Maybe not. It is a nice panel, and I'm sure your electrician would be happy to put it in for you. To change a panel is 4-6 hours depending on what's involved. An easy one is 3 hrs, adding a new riser etc. might take most of the day. I'm just trying to save you a few bucks. Ask your electrician about the switch I'm talking about - he'll have to order one for your brand panel, but they aren't expensive. What you're really saving is labor. You're going to spend some $ on the SO cord you need to hook up the generator and etc. also. Even without the panel change, depending how far away the generator is and how hard it is to get there, you're talking about spending a little money. Well worth it, but you could probably buy a new RRA for what this will run you in parts and labor. Why make it more expensive? ETA: Yes, to answer your question, the main breaker feeding the subpanel DOES isolate the subpanel, but you have to have it off when the power comes back on. This is why you want the aforementioned linked main breakers, whether they are built into your subpanel or just installed as I described. Otherwise, the one time you forget to turn it off and the power comes back on, if it goes phase to phase it could A) ruin the genny (likely) B.) Blow the transformer (Good possibility) or C.) start a fire. (possible) This is why you need the new disconnecting means in the subpanel, not the main panel. Hope this helps. |
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Also - as far as replacing the subpanel chassis - that only works with certain models of panels from the same manufacturer, so no. Also, if you try to run that 50amp AC unit you'll likely kick the breaker. Check out the Lowe's site - they have small, 8 space 60A GE generator panels that would be perfect-they come with the breakers linked, but are more the size you are looking for. They were on the 2nd page when I typed in generators in the search. I still favor just adding a panel - or getting a bigger generator. 30amps will run a lot of stuff, but I'd run #8 wire out to the generator instead of #10 because you're going to want to size it for max load. 6250 watts at 240 is 26 watts or so, but a pump or the 30A AC unit you mentioned can pull that by itself on startup. Check your AC units for FLA specs - that's Full Load Amps. There should also be one for running amps - like I said, they'll spike on start-up, then run at a lower amp draw. Most motor loads are this way. Pumps, AC, fridges, etc. |
Sorry for the long time to get back, but getting the transfer switch issue resolved is now a top priority after the holidays and work year end. The smaller panel is fed from the larger one via a 30 amp breaker in the larger/main panel There are no exterior disconnects that I am aware of. The meter is on the side of the house, line runs down from the meter and into the exterior wall right above the sill for the foundation then inside house where about 2 feet down in the base ment is a large framed wall with plywoodsheets that have the large and small panels mounted. The feed from the meter runs right into the main panel. |
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OK I’m not an electrician, but teach electronics. A cheap safe way to do this is simply.... Install a manual disconnect to all in coming power. Tie in a cable to run off the generator DOWN STREAM of the disconnect. Make a Pigtail, or a receptacle box, to hook the generator to. If power goes out, pull main disconnect, hook up generator to pigtail, or plug in. Turn off all unneeded circuits, start generator. That will give you power to your old distribution system and insulate you from the power grid. Yours will not back feed in to the grid, and when the power comes back on, it will not feed in to yours. When power comes on, turn off generator, disconnect generaror, turn your circuit breakers back on and reconnect main power. That's a lot of a lot cheaper and works. With nothing much to go wrong. This is how mine is done. 
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How about just buying a double throw disconnect that will pass inspection and won't blow up in your loved ones face when they forget to turn the genset off. It is not that much more expensive. |
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Here's that interlock setup. www.interlockkit.com/typicalinstall1.htm My panel is a direct feed from the backside, no sub panel and I've settled on this approach. Basically, it's a mechanical linkage that permits one set of breakers to be flipped, but forces you to flip the other breaker off . There's mechanically no way to accidently have them both on. Meets code and fairly cheap.  I have only a couple of kw in generator capacity in 120 volts, so I can't handle the central a.c. What I'm going to do is wire the one hot 120 volt phase to each of the hot sides of the 3 wire. Net difference between the hot legs is then obviously zero -- so 220 volt stuff won't be energized, but I'll have 120 volts available everywhere I do need it - fridge, lights, freezer, furnace and a window a.c. |
+1000000 That is the way to go, I have installed a few, and its what I have in my house. |
That is amazing that they get $150 for those when you really look at what they are. Clever setup, though, and they gotta pay for the UL goodness. Props to a guy with a good idea. I remember a thread about bonding, and how a portable generator likely has ground and common bonded. Being you don't want to have your electric bonded at more than one point, it would seem this setup does not reconcile that conflict, whereas a transfer switch with a separate grounding bar (ala sub panel) does. Can a portable generator be un-bonded for home use? Maybe dive into the internal wiring and install a switch? (assuming portable functionality was to be retained) Or correct me if I'm smoking the crack. Not an electrician, just a generally handy sort seeking knowledge. |
| I have a genny similar to yours. I bought a 6 circuit manual transfer switch from Lowes for $300. It came with everything you need including color detailed instructions. I know it should be professionally installed. However it was very easy to do. I'm just saying. It also has analog power meters for each side so you can balance the load. I run the furnace, well, 1 bedroom, 1 bathroom, parts of the kitchen and basement. |
I am hoping you are using a double throw switch and your drawing just didnt come out right.... otherwise, while you might be an electronics whiz.... you dont get electrical safety. |
+1 I used this one: 10 breaker switch Had an electrician install it so that he could do the work of running the outside inlet where I wanted to run the generator, works like a champ. Has meters to show me the load on the circuits I've switched over, very good way to manage the load. I'd love to have a big whole-house genny with an automatic switch, but the cost is so high and I need the backup power so rarely that I can't justify it. |