[miogpsrocks]

What do I need to connect a portable backup generator to my house?

I already have a 50KW backup generator with a manual transfer switch however its old and unreliable and was impossible to get propane refill during the last hurricane.

I would like to be able to connect a portable generator ( current like 8,000 Watts) to my house with the option of getting a larger generator in the future.

Even know the portable generator is not powerful enough to run everything. It should be able to handle some basic things.

Would energizing the same circuit that the older generator in somehow backfeed into the generator and cause a problem or do they have some device that allows power to flow out of the generator but not back the other way?

Thanks.

 

[u2slow]

Would energizing the same circuit that the older generator in somehow backfeed into the generator and cause a problem or do they have some device that allows power to flow out of the generator but not back the other way?

Short version... (not knowing your expertise)

Remove the old generator's feed to the transfer switch, and connect the new one in its place. The connecting cable need not be larger than what the generator can supply.

Its up to you to use good judgement in what circuits you energize.

 

[Bondo]

Would energizing the same circuit that the older generator in somehow backfeed into the generator and cause a problem or do they have some device that allows power to flow out of the generator but not back the other way?

Ayuh,..... If the generator is the only power supply, what's gonna back-feed it,..??

Just hook it up through the old manual transfer switch, 'n turn off some of the circuits on the main panel, so you don't overload the new smaller gen-set,....

 

[miogpsrocks]

Ayuh,..... If the generator is the only power supply, what's gonna back-feed it,..??

Just hook it up through the old manual transfer switch, 'n turn off some of the circuits on the main panel, so you don't overload the new smaller gen-set,....

The other generator? I am talking about having 2 backup generators.

My main generator is extremely powerful but old, unreliable and runs out of propane quickly. The portable generator is small, runs of gasoline and only able to run a few things at a time.

Assuming a situation that: Generator #2 powered

Generator #1 is off but still hardwired into the home.

If both Generator #1 and #2 are connected to the same circuit. Is that going to cause problems?

Currently the setup is the generator has a transfer switch which takes the entire house off the grid power and switches it to the generator power.

Up is Grid power, and down is generator side power.


If the switch is down for generator power, then I have an option of my main generator or my portable generator.

Assuming I connect a power inlet switch into the generator side of the circuit, that would mean I have 2 generators on the generator circuit.

If portable generator is on, will that screw up the main generator?

Do generators have some kind of 1-way check value for electric?

 

[u2slow]

If the big generator has its own main circuit breaker, it shouldn't be a problem.

 

[Kevin_Essiambre]

I'd probably install another transfer switch or something to switch between generators, but 50KW is big... 200-225 amps big, so you'd need something rated for that amperage.

Just my 2 cents.

 

[miogpsrocks]

I'd probably install another transfer switch or something to switch between generators, but 50KW is big... 200-225 amps big, so you'd need something rated for that amperage.

Just my 2 cents.

Why would you need a second transfer switch when I already have one that is able to separate the Grid power from the generator power?

When I flip that switch all the way down, the house is connected to the generator and there is no grid power.

In order to do that again, would require a something that cost thousands of dollars in order to be able to handle the large generator.

All I am looking to do is get another hook up for a smaller portable generator in the event the main generator breaks or runs out of fuel during the next Hurricane like it did last time.

During last hurricane, I was without power for like 15 days.

The water pump on the generator broke on day 2. Even if it did not break, I only had enough fuel for another day.

We had to run much of that time using a portable generator we got at the home depot however we had a million wires and plugs running all over the house to get power to the fish tank's air pump,etc...

All our food went bad because there is no way to get power to the fridge.

Why would I need a second transfer switch and spend thousands on it?

Thanks.

 

[chandler48]

What size propane tank do you have. I have a 22k generac with a 320 gallon tank and it barely scrapes the top off the propane when it has to run a day or so. Gasoline, on the other hand will be a PITA to fill up every two hours. PLUS, if there is no grid power, where will you get gasoline from, since gas stations will be without power to pump it, too.

I understand the generator may be unreliable, but why not spend a little and get it running right?

 

[Bondo]

Why would I need a second transfer switch and spend thousands on it?

Ayuh,..... It could be done with a breaker box, or dependin' on how it's wired, at the current breaker box,......

It would have to be wired so that only one gen-set at a time can be active,....

 

[Kevin_Essiambre]

Why would you need a second transfer switch when I already have one that is able to separate the Grid power from the generator power?



When I flip that switch all the way down, the house is connected to the generator and there is no grid power.



In order to do that again, would require a something that cost thousands of dollars in order to be able to handle the large generator.



All I am looking to do is get another hook up for a smaller portable generator in the event the main generator breaks or runs out of fuel during the next Hurricane like it did last time.



During last hurricane, I was without power for like 15 days.



The water pump on the generator broke on day 2. Even if it did not break, I only had enough fuel for another day.



We had to run much of that time using a portable generator we got at the home depot however we had a million wires and plugs running all over the house to get power to the fish tank's air pump,etc...



All our food went bad because there is no way to get power to the fridge.



Why would I need a second transfer switch and spend thousands on it?



Thanks.

All a manual transfer switch is, is a 2 or 3 pole, double throw 3 position switch.

Another transfer switch would be used to switch between the generators.

If you just wire a cord into the feeder from the big generator, you'd end up with a live male end. Leave that connected to your small generator and you could damage the small generator.

I suppose there would be a way to do it using some contactors and some basic relay logic, but you'd still need a contactor that would handle 50KW... at that point, you'd be better off with a transfer switch option.

You could use a small (like an 8 circuit) MLO panel that's rated for your large generator amperage, install a breaker that could handle the amperage (whatever the amperage of overcurrent is on the generator already, 200 or 225 amps?). Use a small breaker for the small generator, and install an interlock kit.

But if you're only worried about a couple of circuits to run off of the small generator, I'd just do a small subpanel with critical/essential circuits, with an interlock on it instead.

 

[dmxtothemax]

What do you currently have on your existing system ?
Do you have an interlock ?
Or a change over switch ?


The simplist method would be to instal
a change over switch to select which generator
feeds the existing facilities.


But you will have to be mindfull of load constraints.

 

[AllanJ]

... Why would I need a second transfer switch and spend thousands on it? ...

Wire up the second transfer switch between the two generator inlets and/or outputs with the common (output) going to the generator side of the first transfer switch.

Comparable to pairing up sports teams to make up a playoff schedule. For this example the utility power has a "bye", there being no fourth power source to pair up with in semifinals.

There is no such thing as a "check valve" for alternating current electricity. You must have switching to keep power from one generator from going up the output wiring of the other generator.

Your second transfer switch, never traversed by utility power, should not cost thousands. Low hundreds at worst, most likely much less.

 

[readydave8]

You need a way to only have one generator to be electrically connected at a time, for example(as others have said )turn off breaker built into large genny, plug smaller generator into power inlet