Portable generator / transfer switch questions -

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Old 08-06-20, 08:15 AM
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Portable generator / transfer switch questions -

1) For a big portable generator (5000 w), it can put out 240v / has 2 120V circuits.

https://az417944.vo.msecnd.net/diagr...am/diagram.gif

If you just use just 1 of the 2 seperate 120v outlets for hours / days at a time, is that a problem? (no load on 1 120V circuit, a big fridge on the other). Should you change the outlet you are drawing from? hourly? daily? to help balance the load?

2) Looking to install a transfer switch for this. But they don't have many circuits. Realisitcally, we'd like to power most all the lights in the house (LED these days, so not much draw). but they are on different circuits in the electrical panel. and too many for the transfer switch.

Is there a work around? We'd envision wanting to have the ability to power most all recepticals, lights, etc. in the house. (just not A/C. Stove is gas so not an issue with that) And just realize you can't run the clothes washer, dishwasher, fridge, toaster, hair dryer all at the same time / not have all the lights / TVs on at the same time. Just to have the ability to turn them on 1 at a time.

Can't do that? Kinda want a transfer switch for the main line? Does that exist? Just like you mmight have 200 amp service coming in, add up everything in the house and it can't all run at the same time without popping breakers. / it would add up to more than 200 amps?

THANKS!
 
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Old 08-06-20, 10:10 AM
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If you have one big '120 volt fridge or other appliance then you have no other choice, you plug it into one 120 volt receptacle or you plug it into the other receptacle on your generator.<br /><br />Yes it would help of you alternate which receptacle you plug it into, or if you do have other small items you plug those into a ppower strip that plugs into the other 120 volt receptacle.<br /><br />Yes you can get and install a whole house transfer switch (one big toggle as opposed to 10 or so little toggles)., then feed it with a small generator. Use manual discipline to avoid overloading the generator.
 
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Old 08-06-20, 10:32 AM
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You might also reconsider your approach for using your portable back up generator. Instead of trying to accommodate all of the normal and convenient household electrical needs why not recognize that you are on emergency power and limit your loading only to those items of critical need until normal electricity is restored. A heavily loaded generator is also going to be burning more fuel - which means more filling and more trips to the gas station. If you really need to power your house at a "normal" level you might consider a stationary generator.

I have a portable 6500 W generator. I easily power the fridge, my well pump, a 20 Amp kitchen circuit (microwave, toaster oven, toaster etc) and two lighting/entertainment circuits. No water heater (ours is electric), no dishwasher, oven or cooktop - all of which we can live without during a typical power outage of just a few days.
 
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Old 08-07-20, 06:57 AM
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There are many manufacturers of automatic transfer switches that can be used with standby generators. These units automatically start the generator on loss of utility power, isolate the home electrical from the utility, and connect the home electrical to the generator. When utility power becomes available, the transfer switch reverses the sequence. While a transfer switch is available for a portable generator, nothing is automatic and must be done by a person when a loss/return of power is determined. The most important operation is to isolate the home electrical from the utility before the portable generator is connected. Failure to do so can result in injury to a utility linesman, damage to your generator , etc., so be diligent.
 
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Old 08-07-20, 07:44 AM
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Frequently loose power here for days on end. Have 7.5 kw alternator with natural gas adapter on wheeled cart (is not covered by building codes). Has range type 50 amp male power cord that plugs into garage arc welder outlet during power outages.

When power goes off turn off main power panel breaker. Plug in alternator and start it.

In old days, when on alternator, looked for neighbors lights as sign that utility power had been restored. When neighbor's also got alternators had to find new way to learn when power was back.

Made module with battery powered piezo electric sounder and cell phone 100-250 volt power adapter. Has wires with 1 amp uses on each leg.. During outages connected to electrical panel utility side of 240 volt breaker.

Turn off alternator at night. Last few days have been without power. Woke up this morning to buzzer sounding. Unplugged alternator and turned on main breaker till next time.

https://www.amazon.com/s?k=piezo+sou...b_sb_ss_i_10_7
 
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Old 08-08-20, 06:44 AM
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doughess > I ain't no expert and I surely ain't very smart but ummmmm, that doesn't sound very legal or safe.

Is it?

 
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Old 08-08-20, 07:48 AM
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I have long experience in electrical and electronic systems. I am hyper about safety.

Upon a electric power failure, first step is always to turn OFF main breaker. Second go to garage and plug in generator. There are 3 breakers that must be closed for generator to connect to panel bus.

While running on generator return of utility power activates buzzer. Go to panel, turn OFF breaker from generator. Turn ON main breaker and disconnect buzzer.

That is safety first.

Mod Note- This is not code compliant and is not safety first.
 

Last edited by pcboss; 08-09-20 at 05:55 AM.
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Old 08-08-20, 07:57 AM
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""... Has range type 50 amp male power cord that plugs into garage arc welder outlet during power outages. ... ""

Very unsafe and not permitted.

"" ... I am hyper about safety. ... ""

Sentence inconsistent with previous quoted sentence above.

You must never construct, possess, or use a cord or adapter with its two ends both male.

"" ... As extra caution removed their seal on electric meter so can remove it when running generator. ... ""

Removing the meter seal is not permitted. Then the power company may estimate you electric bill and you may not protest or dispute their numbers even if both your past history and future usage do not match or correlate with their numbers..
 

Last edited by AllanJ; 08-08-20 at 08:17 AM.
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Old 08-09-20, 05:30 AM
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Safety first is a motto every one needs to follow.
But, it is possible and even highly likely that a person can make a mistake.
To risk the health and safety of a power line worker, by a family member who may once seen a bogus cord being hooked up and trying it or the "safe expert" making a mistake is irresponsible.......considering that a safe hook-up should be affordable or a worthwhile expenditure.
The odds are better for an expert to make a mistake than wining a lottery,
Just as bad as doing this is the idea that someone would brag about or promote a bad idea.
 
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Old 08-10-20, 06:36 PM
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On cold winter nights when power fails, my family safety is #1 and run generator.

Local utility guys have seen the setup.

For those concerned about safety here are additional safety items:

https://www.google.com/search?client...UTF-8&oe=UTF-8
 
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Old 08-10-20, 07:54 PM
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You might also reconsider your approach for using your portable back up generator. Instead of trying to accommodate all of the normal and convenient household electrical needs why not recognize that you are on emergency power and limit your loading only to those items of critical need until normal electricity is restored. A heavily loaded generator is also going to be burning more fuel - which means more filling and more trips to the gas station. If you really need to power your house at a "normal" level you might consider a stationary generator.
Sounds to me like OP is well aware that his 5kw generator can't power everything, and that he must alternate his heavier draw appliances. He just doesn't want to be forced to give up access to certain circuits while on generator power, which is what the typical transfer switch does.

I'm in the same boat, which is why I'm looking at a generator interlock instead of a transfer switch. OP, with an interlock, your generator backfeeds your main panel. That power is available for use by any circuit in the main panel. As you already know, you have to be judicious about it and realize your power source is a portable generator and use devices accordingly.

And you need an interlock, which is just a piece of sheet metal that prevents you from having both main breaker and generator breaker on at the same time (otherwise you would backfeed the grid from the running generator and potentially electrocute a poco employee working on the line).
 
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Old 08-11-20, 04:34 AM
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"You must never construct, possess, or use a cord or adapter with its two ends both male."

In the military we had a name for a double ended male cord. We called them "suicide cords"
 
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Old 08-11-20, 09:46 AM
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Sizing generator is like buying life insurance. Minimum size will power heating, refrigerator
and a few lights. Full capacity would will run central AC, electric stove, oven, Jacuzzi, etc. Take your choice.

How to connect generator to panel is another story. My 200 amp panel equals 48,000 watts. A transfer switch to connect 7.5 kw 26 amp generator was a sanity check.

The 7.5 kw runs everything but central AC. When microwave 1200 watts kick on is barely noticeable. While modern homes have more electric powered items they use less power than old ones. Typical winter evening generator output is around 10 amps, less than 50% of generator capacity.

Years ago when community lost power for many days I ran out of gas for generator. Could not buy any at local stations which also had no power.

Bought gas conversion kit for generator. Basically a gas valve activated by intake manifold vacuum that feed gas to air horn adapter on carburetor. Most propane dealers sell them, easy install.

Another military way. Sixty years years ago was at remote Air Force site on Taiwan. During typhoons Commander would set up Command post in Officers Bar. During one typhoon watched him throw a fit when no one would go 30 feet up on pole to flip transfer switch.

As my first post college job, considered military a lesson in "how not to do things". There was right way, wrong way and military way. Maybe was one of factors in becoming a DIYer.
 

Last edited by doughess; 08-11-20 at 12:40 PM.
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Old 08-11-20, 11:43 AM
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Thank you all for all this info! Yes, interlock is what i need vs. transfer switch.

I realize I can't turn everything on at once. If I do, best case the generator stalls / circuit breaker pops. Worst case - things fail because of the low voltage (I shouldn't jinx it but surprized my 20 year old fridge still keeps running after all the times I connected it to generator).

Now the question:

Right now, I have a husky HU5000 - L14-20R receptacle and a pair of 'regular' 3 prong receptacles. and it has 2 - 20 amp breakers

I ran 65' of 4 conductor 8AWG from from garage thru basement to panel.

At some point I might get a new / bigger generator? Home Depot / costco has generators with L14-30R receptacles

Can / should I use an L14-30R in the garage on the wall? Then a jumper cable 30 to 30 and adaptor 30 to 20 for this generator? Or stay with 20 on everything in the garage and have to change cable and wall connnector when I get something new?

Same for in the panel, would you use 20 amp or 30 amp breakers?

Finally, that male to male cable you guys mentioned... <sheepish grin / shame?> I do have 2 of those with the 'normal' 3 prong connectors. I realize it's not ideal.

@allanj

Is that line: "You must never construct, possess, or use a cord or adapter with its two ends both male."
a cut / paste from NEC code or just common sense : ) ??
 
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Old 08-11-20, 12:46 PM
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"surprized my 20 year old fridge still keeps running after all the times I connected it to generator)."

My guess is that your 20 year old fridge is better able to handle a generator's often dirty power than one of the newer models. I semi cringe every time I connect my fridge to a generator.
 
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Old 08-11-20, 01:06 PM
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Here in suburban NY building codes require permanently installed generators to have permits and meet codes.

A generator on wheels with plug is not covered by code.

Building electric wire size/amp rating determines max panel breaker size.

For outlets and generator cable to it I go to next higher amp rating.
 
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Old 08-11-20, 01:22 PM
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I'm late to this party. Just read the OP's 1st post.
If you want all outlets and all appliances to work during a power outage then you don't want a transfer switch or an interlock. You want a whole house natural gas or propane generator.

I don't mean to sound sarcastic, but during a power outage (temporary or prolonged) you don't need all the conveniences of everyday life. You need power enough to sustain a reasonable ability to live. If you want more then pay the price of a whole house generator.
 
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Old 08-11-20, 01:23 PM
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Home is high on hill with frequent electrical issues. Permanently wire into panel a 3 wire (Not 2 wire) transient protector, through 20 amp 240 volt breaker. Every home should have one regardless of electric power source.

Even though it is on side circuit it holds down transients on panel buss. If it goes bad, breaker pops.

In a modern home it protects all tech semiconductor based items that are susceptible to transients.
Most use same MOV technology, so quality is little issue. There are many models with crazy pricing.

https://www.supplyhouse.com/e modern home Square-D-SDSA1175-Type-1-3-Wire-Surge-Protector-120-240V-36-kA
 

Last edited by doughess; 08-11-20 at 01:41 PM.
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Old 08-11-20, 07:39 PM
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@norm201 - someone else was saying the same thing. Not sure if I'm asking too much or my house is wired bad? With a bout 3 dozen 'circuits' / breakers, even just all the lights in the house are spread out across 10? circuits / breakers (I'd have to count). It's a 2,500sq ft,. 4 br, 2 1/2 bath house - 200 amp service, not a huge house?. then a fridge in the garage (andother breaker), fridge in the kitchen (another breaker) , heat (gas fired hot water so you need electric for circ. pump) another breaker, and can I have 1 or 2 outlets to charge a cell phone? all those and you are over the capacity of a transfer switch. And that's not having the ac, dishwasher, clothes washer,etc.

Am I asking too much to be able to do that with a portable generator? I don't think so. And if I want to make a game of not having all the lights on at the same time, maybe I can do some wash? I don't want all the lights and outlets / devices to work at the same time. Just have the capability to fire them up. We were out of power for 2 weeks a few years ago. Buit we pulled it off with a jury rigged arrangement - backfeeding and main line turned off. Want to do it right way with portable generator\.
 
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Old 08-11-20, 07:42 PM
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@babaganoosh, you'll be fine. I think some people are reading your posts as wanting to power a lot of loads simultaneously, even though you made it pretty clear you don't want or need to do that. You just need the ability to power lots of different circuits at different times.

Part of the confusion may be that you have ~3 dozen circuits because so many are dedicated to one appliance. In older homes, there are often far fewer circuits, with many loads on each circuit. For someone in that situation, a transfer switch with 8 circuits may cover everything they need or want for the duration of a power outage.

In your situation, an interlock will meet your needs much better. And since you likely have others in the house, it may make sense to flip off less necessary circuits so they don't inadvertently get used while the genny is running a bunch of other loads.
 
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Old 08-11-20, 08:08 PM
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Thanks! So back to the question at hand - am I allowed / should I use L14-30 connectors / jumper cord out in the garage even though the current generator has L14-20R receptacle (and yeah, I'll need adapter to go from the L14-30 cord to the L14-20 on the generator.
 
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Old 08-12-20, 08:43 PM
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At 5 kw 240 volts, amps would be 20.83333

Is always better to go to next size larger current rating on wire and connectors. Dirty contacts and corrosion can created issues, so a little insurance is nice.

Another interesting point is each side of generator 120 vac is usually limited to 20 amps or 2.5 KW. Stated another way, you usually cannot pull 5 kw off just one side.

You might want to thinks about balance load on each side of electric panel for more even load when on generator.
 
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Old 08-15-20, 07:37 AM
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For my interlock setup, I'll have to run wire from main panel through concrete wall of basement to the inlet on exterior of house. Can I use NM-b wire for this or does it have to be UF-b? The hole will be above ground, but I'm wondering if the porous nature of concrete changes the wire allowed by code.
 
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Old 08-15-20, 08:06 AM
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@cartman I thought I'd try to help with this (and am in the same situation going through a concrete block above ground) and hadn't thought about it.

my head spins:
First I saw this:
https://www.garagejournal.com/forum/...d.php?t=430515

Then all the parts of the code:

https://diy.stackexchange.com/questi...hrough-conduit

Post here what you come up with : )
 
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Old 08-16-20, 07:44 AM
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"Here in suburban NY building codes require permanently installed generators to have permits and meet codes.

A generator on wheels with plug is not covered by code.

Building electric wire size/amp rating determines max panel breaker size.

For outlets and generator cable to it I go to next higher amp rating."

Doughess, I'm sure that inlets, transfer switches, or interlocks are covered by code. You're right only with use of extension cords,
 
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Old 08-17-20, 11:17 AM
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patmurphey post # 25 has made a comment about dougherss post writing than “only” the ones about extension cords are “right”. Are doughess other points wrong?

doughess never suggested that codes do not cover “inlets, transfer switches, or interlocks “

DIY posts are a reflection of the writer's credibility and stand by his.
 

Last edited by doughess; 08-17-20 at 12:51 PM.
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