5 ms·

Connecting a Portable Generator to the Home Main Electric Panel

23 points by hourislate 5y ago

CapitalistCartr 5y ago
When doing this, homeowners invariable seem to "reinvent" suicide cords, a short cord with two male ends. DO NOT DO THIS. No matter how sure you are that you're too smart to mess up. Or too calm. Or whatever. Pay the money, use a transfer switch. Or interlock kit. But preferably a transfer switch. They are pretty idiot proof.
- Arrath 5y ago
  For anyone reading, do not ignore this advice.
- stirfish 5y ago
  Why would I reinvent it when I can buy it for $13 from Walmart? https://www.walmart.com/ip/FR-4-2-Pin-Style-Power-Connector-Extension-Cable-Male-to-Male-Connector-Extension-Cord-for-Electric-Recliner-and-Lift-Chairs/533716969 https://www.walmart.com/ip/FR-4-2-Pin-Style-Power-Connector-... Edit: this one has three prongs, for safety :) https://www.amazon.com/Linmunster-%EF%BC%8CDouble-Extension-Generator-Transfer/dp/B09RWTHY7P/ref=mp_s_a_1_3 https://www.amazon.com/Linmunster-%EF%BC%8CDouble-Extension-...
- londons_explore 5y ago
  One could theoretically invent a 'suicide cord' with a relay inside which only connected the ends together if it detects it is connected to the main breaker box and is not connected to the grid. That could be done by having a keychain-style device that clips around the incoming electricity cable to your house and sends a signal that would be detected by the 'improved suicide cable'.
  - deleted 5y ago
    [deleted]
deleted 5y ago
[deleted]
SOLAR_FIELDS 5y ago
I recently paid an electrician to do the exact work discussed in the article on my home in Austin, TX. Total cost for installation of the inlet, 50 amp breaker, and interlock kit as well as a 25 foot heavy duty cable with 6-50P that hooked my generator up to the inlet was about $1K. A 8500W sustained 11000W surge generator from Northern Tool that’s enough to power my whole house for 3 days or so with two 5 gallon jerry cans was another $1300. If you do go generator shopping, sizing is important, but it’s also important to look for a generator with low Total Harmonic Distortion (<5%) if you plan to use it in your house else your sensitive electronic devices may be damaged. Surprisingly, a large majority of generators on the market, including the ones sold by Costco, don’t have low THD. GeneratorBible website is a good resource for comparison shopping and education. We mainly made the purchase for peace of mind after last year’s “incident” (even knowing that it was a once in 30 year storm). Transfer switches are another alternative, but are more expensive and can only handle the 4-6 breakers you assign to them. Interlock kits can use any breaker. So at higher expense you get less functionality in exchange for a solution that is slightly more foolproof.
- bradknowles 5y ago
  Note that generators are not designed to be used indoors, and are likely to lead to major health risks and even death if you do so. Not even in your garage. Be careful out there!
  - SOLAR_FIELDS 5y ago
    Yes, I realize now that my comment could have been interpreted as actually running the generator inside. NEVER do this. Outside only. What I meant to say in a more clear way is that if you intend to use the generator to power items inside your home that you should use a generator with low THD unless you are only using your generator for something like operating a heater or furnace.
- londons_explore 5y ago
  > generator with low Total Harmonic Distortion With any electronic device built after the 90's, this will not be an issue. Everything that uses a switched mode power supply doesn't care about the waveform. The waveform shape will likely only affect devices from before the 90's with inductors trying to do clever things, such as florescent lights. With a very poor waveform, classical induction motors will run hotter. That includes fridge compressors and fans in furnaces, pumps in dishwashers, etc. I doubt any will fail though - they normally have a decent thermal margin.
klondike_ 5y ago
>I chose the Square D Circuit Breaker, 60 Amp, 2-Pole, QO260 instead of the QO230CP QO 30-Amp Two-Pole Circuit Breaker because the price difference was negligible and I always liked the concept of over-sizing specifications. Big mistake! The breakers in your service panel are to protect your wiring from overheating by drawing too much current. The 10ga wire he used is only rated for 30A, so it should be on a 30A breaker. Having more current than that could melt the cable or damage the generator. Bigger isn't always better when it comes to circuit breakers
- quickthrowman 5y ago
  The generator has a 2P 30A circuit breaker protecting the L14-30 output, the backfeed breaker isn’t acting as overcurrent protection (it’s just a disconnecting means) so the oversizing is OK in this case. In general and excluding inductive motors, your advice is correct.
maxerickson 5y ago
Anybody have a http://www.generlink.com/ http://www.generlink.com/ installed? It's a transfer switch that installs behind the meter, so not a lot of work to enable selecting loads using the main panel. I guess it is comparatively expensive for the load it supports (my use case would be the furnace and some lights though).

23 points by hourislate 5y ago

When doing this, homeowners invariable seem to "reinvent" suicide cords, a short cord with two male ends. DO NOT DO THIS. No matter how sure you are that you're too smart to mess up. Or too calm. Or whatever. Pay the money, use a transfer switch. Or interlock kit. But preferably a transfer switch. They are pretty idiot proof.

Arrath 5y ago
For anyone reading, do not ignore this advice.
stirfish 5y ago
Why would I reinvent it when I can buy it for $13 from Walmart? https://www.walmart.com/ip/FR-4-2-Pin-Style-Power-Connector-Extension-Cable-Male-to-Male-Connector-Extension-Cord-for-Electric-Recliner-and-Lift-Chairs/533716969 https://www.walmart.com/ip/FR-4-2-Pin-Style-Power-Connector-... Edit: this one has three prongs, for safety :) https://www.amazon.com/Linmunster-%EF%BC%8CDouble-Extension-Generator-Transfer/dp/B09RWTHY7P/ref=mp_s_a_1_3 https://www.amazon.com/Linmunster-%EF%BC%8CDouble-Extension-...
londons_explore 5y ago
One could theoretically invent a 'suicide cord' with a relay inside which only connected the ends together if it detects it is connected to the main breaker box and is not connected to the grid. That could be done by having a keychain-style device that clips around the incoming electricity cable to your house and sends a signal that would be detected by the 'improved suicide cable'.
- deleted 5y ago
  [deleted]

deleted 5y ago

[deleted]

SOLAR_FIELDS 5y ago

I recently paid an electrician to do the exact work discussed in the article on my home in Austin, TX. Total cost for installation of the inlet, 50 amp breaker, and interlock kit as well as a 25 foot heavy duty cable with 6-50P that hooked my generator up to the inlet was about $1K. A 8500W sustained 11000W surge generator from Northern Tool that’s enough to power my whole house for 3 days or so with two 5 gallon jerry cans was another $1300. If you do go generator shopping, sizing is important, but it’s also important to look for a generator with low Total Harmonic Distortion (<5%) if you plan to use it in your house else your sensitive electronic devices may be damaged. Surprisingly, a large majority of generators on the market, including the ones sold by Costco, don’t have low THD. GeneratorBible website is a good resource for comparison shopping and education. We mainly made the purchase for peace of mind after last year’s “incident” (even knowing that it was a once in 30 year storm). Transfer switches are another alternative, but are more expensive and can only handle the 4-6 breakers you assign to them. Interlock kits can use any breaker. So at higher expense you get less functionality in exchange for a solution that is slightly more foolproof.

bradknowles 5y ago
Note that generators are not designed to be used indoors, and are likely to lead to major health risks and even death if you do so. Not even in your garage. Be careful out there!
- SOLAR_FIELDS 5y ago
  Yes, I realize now that my comment could have been interpreted as actually running the generator inside. NEVER do this. Outside only. What I meant to say in a more clear way is that if you intend to use the generator to power items inside your home that you should use a generator with low THD unless you are only using your generator for something like operating a heater or furnace.
londons_explore 5y ago
> generator with low Total Harmonic Distortion With any electronic device built after the 90's, this will not be an issue. Everything that uses a switched mode power supply doesn't care about the waveform. The waveform shape will likely only affect devices from before the 90's with inductors trying to do clever things, such as florescent lights. With a very poor waveform, classical induction motors will run hotter. That includes fridge compressors and fans in furnaces, pumps in dishwashers, etc. I doubt any will fail though - they normally have a decent thermal margin.

klondike_ 5y ago

>I chose the Square D Circuit Breaker, 60 Amp, 2-Pole, QO260 instead of the QO230CP QO 30-Amp Two-Pole Circuit Breaker because the price difference was negligible and I always liked the concept of over-sizing specifications. Big mistake! The breakers in your service panel are to protect your wiring from overheating by drawing too much current. The 10ga wire he used is only rated for 30A, so it should be on a 30A breaker. Having more current than that could melt the cable or damage the generator. Bigger isn't always better when it comes to circuit breakers

quickthrowman 5y ago
The generator has a 2P 30A circuit breaker protecting the L14-30 output, the backfeed breaker isn’t acting as overcurrent protection (it’s just a disconnecting means) so the oversizing is OK in this case. In general and excluding inductive motors, your advice is correct.

maxerickson 5y ago

Anybody have a http://www.generlink.com/ http://www.generlink.com/ installed? It's a transfer switch that installs behind the meter, so not a lot of work to enable selecting loads using the main panel. I guess it is comparatively expensive for the load it supports (my use case would be the furnace and some lights though).