[Master Brian]

I'm looking into installing a transfer switch so I can run a portable generator. FYI...I have two. One is gas, one is propane, both are Generac and I believe about 3200watts.

Most every light in my house is now led, so not much draw there, I could easily run a few lighting circuits. I'm trying to figure out which outlet, circuits is want to tie into to figure out what my demand would be so I can choose the correct switch.

Problem is, I know my generators aren't pure sinewave, but not sure what devices that would affect. That's really what I need to know. I've heard an easy fix is to use a battery backup/ surge protector device between the generator and sensitive devices.... even if battery is no good. Is this true? Wouldn't battery need to be good in order to clean up the power?

I'm thinking grabbing the furnace circuit, a basement circuit for power down there to possibly power deep freeze and an old 1950s fridge we keep drinks in and spillover food. Then the kitchen circuit the fridge is in and maybe another set of circuits.

Would the fridge, with its controls be compromised by the generator? It has an appliance surge protector on it. What about TVs? Furnace?

Any incite is appreciated.

 

[seharper]

Firstoff, avoid those janky 6, 8 or 10-switch "circuit by circuit transfer switches". They are cheaply made, built by second-tier builders like Reliance, cost a fortune, have very complex wiring, and does not work with GFCI/AFCI breakers because of the stupid way they handle neutral.

The single best transfer switch I've ever seen is a tricked out subpanel. You start with, say, a $70 Siemens/Murray 24-space main lug panel. Siemens is a first rate supplier. (I know some folks are up in arms about "too many spaces", but relax - we'll be losing 4 spaces to the interlock.) You'll also need one or two $6 accessory ground bar kits if they don't "come with".

You add a $25 Siemens interlock kit, which interlocks two supply breakers. One of them brings power over from the main service panel. The other one brings in power from the generator. They act like "dual main breakers" that can't both be on at once.

Once the panel is installed, whichever circuits you want to have on generator - refrigerator, fuel furnace, sump pump, etc. etc. -- you just move those circuits to that panel.

And it wires up just like a normal panel. You use normal Siemens/Murray breakers. If the circuit needs GFCI/AFCI breakers, you just use them. 2-pole breakers? Any number of them are fine. Forgot a circuit? Just move it over now. You have loads of spare space, so you didn't even really need to think about "which eight circuits" to bring over; you have loads of space and can just roll with it.

If your existing panel is cramped, this is a great time to deal with that, because you'll be pulling circuits out of it into this one.

At this point we're into it for $95 + breakers at $5 a pop. It's wired simply, it's obvious, it works, AFCI and GFCI work properly in all modes, and it's first rate.

So you change it over by spinning up the gen, shutting off any big loads, shut off "utility", turn on "Generator" and the whole panel is on gen. Switch any big loads back on one at a time.

 

[RAL238]

I'm looking into installing a transfer switch so I can run a portable generator. FYI...I have two. One is gas, one is propane, both are Generac and I believe about 3200watts.

Most every light in my house is now led, so not much draw there, I could easily run a few lighting circuits. I'm trying to figure out which outlet, circuits is want to tie into to figure out what my demand would be so I can choose the correct switch.

Problem is, I know my generators aren't pure sinewave, but not sure what devices that would affect. That's really what I need to know. I've heard an easy fix is to use a battery backup/ surge protector device between the generator and sensitive devices.... even if battery is no good. Is this true? Wouldn't battery need to be good in order to clean up the power?

I'm thinking grabbing the furnace circuit, a basement circuit for power down there to possibly power deep freeze and an old 1950s fridge we keep drinks in and spillover food. Then the kitchen circuit the fridge is in and maybe another set of circuits.

Would the fridge, with its controls be compromised by the generator? It has an appliance surge protector on it. What about TVs? Furnace?

Any incite is appreciated.

Those are good questions to be asking.

Most portable generators put out sine wave-like waveforms, but they vary greatly in quality. You can see some samples of how good/bad they look here. There's lots of information about generator quality on that web page, if you care to read through it all.

The measurement of waveform quality is Total Harmonic Distortion (THD). Many appliances in your house contain "sensitive electronics" which can be damaged by poor power quality. For them to operate properly, they should have relatively clean power, with THD of less than 5%. Dirty power won't necessarily kill them immediately, but over time, it will do damage, and eventually things fail.

If you have a specific generator model in mind, try a google search of the model plus "waveform" or "THD" and you might get a hit.



Things that contain sensitive electronics cover a wide range, including newer refrigerators, HVAC systems, dishwashers, TVs, computers, even washing machines and dryers. Anything with a microprocessor in it. And some compressors in refrigerators and HVAC systems aren't happy with poor quality power.

A lot of inexpensive generators are over 5% THD. As a result, they don't quote a spec for it, because they don't want you to know. Many are in the 10 to 20% range.

The best power quality comes from inverter generators that produce a pure sine wave, like the Honda EU3000i.

Most UPS power supplies won't help to clean up generator power. When they are running off of "wall power", they just pass it through to the load, without cleaning anything up, except to clamp surges.

An exception would be a Double Conversion UPS, which converts the AC input to DC, and then converts it back again to AC. One thing to watch out for with any UPS that you might try and run off a generator is that many won't operate if the AC frequency is not very close to 60 Hz. Some inexpensive generators don't do a good job of maintaining frequency and the UPS acts as if there is no power coming in and will run on the battery until it dies.

 

[Master Brian]

Firstoff, avoid those janky 6, 8 or 10-switch "circuit by circuit transfer switches". They are cheaply made, built by second-tier builders like Reliance, cost a fortune, have very complex wiring, and does not work with GFCI/AFCI breakers because of the stupid way they handle neutral.

The single best transfer switch I've ever seen is a tricked out subpanel. You start with, say, a $70 Siemens/Murray 24-space main lug panel. Siemens is a first rate supplier. (I know some folks are up in arms about "too many spaces", but relax - we'll be losing 4 spaces to the interlock.) You'll also need one or two $6 accessory ground bar kits if they don't "come with".

You add a $25 Siemens interlock kit, which interlocks two supply breakers. One of them brings power over from the main service panel. The other one brings in power from the generator. They act like "dual main breakers" that can't both be on at once.

Once the panel is installed, whichever circuits you want to have on generator - refrigerator, fuel furnace, sump pump, etc. etc. -- you just move those circuits to that panel.

And it wires up just like a normal panel. You use normal Siemens/Murray breakers. If the circuit needs GFCI/AFCI breakers, you just use them. 2-pole breakers? Any number of them are fine. Forgot a circuit? Just move it over now. You have loads of spare space, so you didn't even really need to think about "which eight circuits" to bring over; you have loads of space and can just roll with it.

If your existing panel is cramped, this is a great time to deal with that, because you'll be pulling circuits out of it into this one.

At this point we're into it for $95 + breakers at $5 a pop. It's wired simply, it's obvious, it works, AFCI and GFCI work properly in all modes, and it's first rate.

So you change it over by spinning up the gen, shutting off any big loads, shut off "utility", turn on "Generator" and the whole panel is on gen. Switch any big loads back on one at a time.

So I've been giving this a lot of thought, but do not have room next to my main panel. Since starting this, I've basically finished out my basement. My main panel is essentially full, which is fine because my entire house has been rewired within the last ten years or less. That said I have a cutler hammer sub panel in my basement. I'm actually needing to move a wire from main panel to this sub to get some space for future mini split install. Thinking of main floor lighting. Everything in basement is on this sub. Lights, deep freeze, furnace, sump pumps, etc.

I've not been able to figure out how/where to install this panel/ transfer switch but it dawned on me tonight, why not just swap out the cuttler hammer sub for this sub and turn the basement sub into my transfer panel. My living room is now in basement and I over wired the circuits so like 3 20amp outlet circuits in the 15x30 living room space, so running a few cords to another floor for power for main fridge, heater, etc wouldn't be issue.

Any reason that wouldn't suffice?

 

[Master Brian]

Followup

I'm guessing number of spaces don't really matter as long as fits my need. Subs like dumb question, but figure I'll ask.

Then, I also found this, which would effectively turn my main panel into the same thing. Is this style dangerous? Or would it suffice and I'd just have to pick and choose what breakers to leave on and not over load my generator.

Amazon.com: Diaotec Eaton Cutler Hammer Challenger BR-200 Generator Interlock Kit (Anodized Aluminum!) for BR Series 150 and 200 AMP Panel

Amazon.com: Diaotec Eaton Cutler Hammer Challenger BR-200 Generator Interlock Kit (Anodized Aluminum!) for BR Series 150 and 200 AMP Panel

www.amazon.com