My parents are elderly and live in an older house, late 50's. Their house is a ranch style about 1,250 square feet with a full basement.

They have a sump pump in their house and when it storms and power is lost they get water in their basement. When we were all younger we use to haul buckets of water up their basement stairs and dump outside. Carrying water up the stairs is no longer an option.

I know there is a sump pump that can be installed with a battery backup but my dad is wanting to power beyond the sump pump as last time when power was lost it was out for a few days. Therefore, he is wanting to generate power to run freezer, refrigerator, sump pump and a few lights. He is considering buying a gas generator and plugging it into an electric outlet in his house. I know nothing about electricity and concerned about their safety.

Can this be done? Is this safe? What must we know/do to help ensure this is safely handled.

How do we calculate how big of generator is necessary to operate these items AND we need to consider start up draw for these items because I understand that is higher than just normal running. Any suggestions on size of generator?

If this is possible, in the winter if power is lost due to an ice storm, could the furnace be connected to the generator for heat?

Thanks in advance for your time and information.

  • OK -- what do your parents have for an electrical panel or panels? (Clear photos of the panel and label are helpful here). Also, what fuel does their furnace run on, how big is their sump pump, and do they have any other loads that might need generator power (like a well pump)? Jul 11, 2018 at 23:49
  • Where is this? US state, city or county. Jul 11, 2018 at 23:55
  • 2
    Generators are often installed by electrical service firms because some electrical panel rewiring is required. If the house isn't too remote, you might be able to get someone out for a free estimate, who could discuss the options.
    – fixer1234
    Jul 12, 2018 at 0:14
  • 1
    You may want the battery backed sump... anyway... for layers of redundancy.
    – Bryce
    Jul 12, 2018 at 7:45
  • Where is the house located upstate NY or Tennesee'ish? Electric, Gas, Oil or other Furnace ? Community served by Natural Gas or NO? If served by Natural Gas you could use that fuel to run your generator.
    – Ken
    Jul 12, 2018 at 8:55

4 Answers 4


A word of warning though. You CANNOT just "plug the generator into an outlet", because 1) when you do that without isolating your house from the now dead utility lines, the power from the local generator will go backward and try to power up EVERYTHING on that line, which might KILL a line worker trying to fix it; and 2) WHEN (not if) the utility power comes back on and the generator is running without being isolated, it could damage the electrical system in the entire house AND fry the generator.

Hire a professional to install it correctly and per code using a "transfer switch" sytem of some sort. it doesn't need to be automatic if that's too expensive, but there MUST be something that meets code in the system. It's literally a matter of life and death.


Installing equipment to provide residential backup electric power is a thriving industry in the US. An internal combustion engine/generator combination automatically takes over when the grid goes down. Some of the engines are diesel, some run on natural gas. Ain't cheap though!

  • 2
    An automated system is pretty expensive. You can save a little with a manual system that you crank up yourself when the power goes out, and then plug in what you need (but still not cheap). But a battery backup sump pump would be a good idea if the generator option is too expensive.
    – fixer1234
    Jul 12, 2018 at 0:06

Can this be done?

NO: Not the way you have proposed.

Is this safe?

NO: Not the way you have proposed.

What must we know/do to help ensure this is safely handled.

1: Your Panel power would be disconnected and a transfer switch would be placed between the power lines coming in to your home and your panel.

2: If you only want to power some devices and not all devices, your panel would be reconfigured for when the Generator was running as to what circuits would be fed.

3: Your generator would need to be properly sized for all of the items you wish to use. Include the heater because in Winter it is either that or some serious electric blankets.

4: Diesel versus Propane - Propane is cheaper and also supposed to be cleaner fuel (if you are concerned about CO2 emissions etc.)

How do we calculate how big of generator is necessary to operate these items AND we need to consider start up draw for these items because I understand that is higher than just normal running.

All of the items you wish to run have a Volt Amps or Wattage rating listed on them -

  1. Refrigerator (900W),
  2. Freezer (900W),
  3. Sump Pump (How big is it? - 800W),
  4. Lights [depends on types, all LED's 200W],
  5. Microwave Oven - 1500W),
  6. Air Conditioner ~ 4000 Watts
  7. Heater
    • If it is heat pump you are fine. @4000W.
    • Gas/Oil/ Heater you are fine < @ 1500Watts.
    • Electric Use 10,000-60,000 depending on unit.

Add all of those up however exclude an Electric Furnace as that is easily a 16Kwatt Generator (and more) ALL by itself. If you really desire it - change the AC to heat pump if you are in the proper climate, if you are too far north for a heat pump or need that reassurance say Tennessee'ish change to gas powered furnace or aqua-therm heater that connects to your hot water heater.

Any suggestions on size of generator?

I am thinking a 16 KiloWatt to 20 KiloWatt unit AS LONG AS you do not have an Electric Furnace!

See this Generator Sizing Guide ^.

In the winter if power is lost due to an ice storm, could the furnace be connected to the generator for heat?

As noted above this depends on the type of heating system that you have and how much generator you are willing to pay $4,000 vs. $10,000 Plus if you have an electric Furnace and Gas is available in your parents community switch to gas - the gas is cheaper, the power consumption becomes negligible (500W - like a computer).

You should definitely hire a professional to install the unit ; the company that will sell you the generator should have an installation included price. You will be glad you purchased the complete package.

  • 4000watts for a heat pump is way small I would expect the value to be closer to 8kw and that number may double or triple when emergency heat mode is on.
    – Ed Beal
    Jul 12, 2018 at 15:20
  • @EdBeal Heat Pump is AC in reverse. If the Unit has an Auxiliary Heat - i.e. Electric Furnace the power usage would be much higher usually a minimum 10KW heating unit is used for Emergency. That is why I put those details about Electric Furnace heating - Once that is involved forget about reasonably priced generators - Electric Heaters can easily require a 25KW unit and higher. You will notice in sizing charts how conveniently Electric Heaters are left out of the sizing check boxes with no explanations. It is cold in the winter and gen is useless for heat in that scenario.
    – Ken
    Jul 14, 2018 at 22:19
  • As I have set up several generators to run a heat pump I installed in all electric homes a generator works fine when properly sized.
    – Ed Beal
    Jul 15, 2018 at 17:09
  • @EdBeal a Heat Pump is an AC unit in reverse - No Big Deal 4000W - unless it uses auxiliary emergency heat of type Electric Resistive Units. An Electric Furnace uses Resistive Wires and depending on unit sizing BTU's the 15KW range is normal. carrierenterprise.com/… . You are not going to power this with a Generator in the $4K-$10k range or with a 8KW unit. You can size for that sure - but the price goes way up.
    – Ken
    Jul 18, 2018 at 3:57

Since you and your parents do not understand electricity, or how to do this correctly, you should go the your local hardware store, purchase a generator, and have it professionally installed. During this process they will help you figure out how big of a generator you need, based on what you want to run, and the installer will install an automatic cutoff which will disconnect the house from the power grid before the generator is engaged.

Doing anything else, not only runs the risk of killing a lineman during a power outage, but MANY, MANY people die from carbon monoxide poisoning due to poorly installed generators.

If money is an issue, then you can simply buy a portable generator and run extension cords to your sump pump and your freezer (through, for example, an cracked window), but again make sure the generator itself is located far enough away from the home so that carbon monoxide is not an issue.

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