Interlock vs. throwing the main circuit breaker for generator powering a house

[buckeyefarmer]

This "issue" gets brought up and argued over at least once a year, it's only January and here it is already.

 

[aczlan]

Only works IF the generator is Hard Wired to the electrical service .

Huh? It will work just as well with a male outlet on its own circuit that you plug the generator into, or a whip that you plug into the generator.

Aaron Z

 

[LouNY]

I found an interesting pdf file on generators and the NEC;

https://www.mikeholt.com/download.php?file.../Generators...Standby...2014NEC.pdf

This pdf shows several permissible transfer switch wirings, most of which do not switch the neutral,
if it is switched there are several bonding and grounding requirement.
Article 702 of the NEC is the provision for standby generators that are not legally required or
mandated emergency generators.

Lou

 

[zzvyb6]

Depends if the generator has a floating or bonded neutral if the transfer switch also switches the neutral.
Only way a neutral is going to send power back to the utility is an incorrect installation.

Consider this: my neighbors a few doors down had a situation where a lightning strike shorted one leg of the 240v to the neutral underground. Lights became very bright, smoke from wall receptacles and after a short while, the entire house burned unto the basement. Because of the insurance delay, water in the basement froze and cracked and split the foundation. If the power had burned itself a disconnect, how would a standby generator without a neutral opening transfer switch reacted to this?

The reason I asked is because a few months ago, I had a 7600v underground line going from a pole to my on the ground transformer burn out and shorted to earth. If it had shorted to a neutral, my house could have been burned. The talk of neutral disconnect is new to this semi-annual discussion.

BTW; the DTE guys showed up here at 10 pm. used a 'thumper' to locate the short, dug it up spliced in a patch and restored power by 1:00 a.m. !

Meanwhile, there is a new device on the market that goes between the meter housing and the backing plate to be used for a home generator connection. What's your opinion of this technique?

 

[bcp]

Meanwhile, there is a new device on the market that goes between the meter housing and the backing plate to be used for a home generator connection. What's your opinion of this technique?

Sounds like a good idea. My electric co. won't allow it. I asked.

Bruce

 

[MossRoad]

Consider this: my neighbors a few doors down had a situation where a lightning strike shorted one leg of the 240v to the neutral underground. Lights became very bright, smoke from wall receptacles and after a short while, the entire house burned unto the basement. Because of the insurance delay, water in the basement froze and cracked and split the foundation. If the power had burned itself a disconnect, how would a standby generator without a neutral opening transfer switch reacted to this?

The reason I asked is because a few months ago, I had a 7600v underground line going from a pole to my on the ground transformer burn out and shorted to earth. If it had shorted to a neutral, my house could have been burned. The talk of neutral disconnect is new to this semi-annual discussion.

BTW; the DTE guys showed up here at 10 pm. used a 'thumper' to locate the short, dug it up spliced in a patch and restored power by 1:00 a.m. ! View attachment 588006

Meanwhile, there is a new device on the market that goes between the meter housing and the backing plate to be used for a home generator connection. What's your opinion of this technique?

I think I've seen those for about 10 years.

 

[grsthegreat]

Anyone have a link to the code that shows the neutral should be switched?

The neutral DOES NOT HAVE TO BE SWITCHED... unless your talking about a separately derived system...which the whole house is not. Residental transfer switches do not switch neutral. A UL approved interlock is aporoved to use as long as main breaker cannot be engaged when generator breaker is engaged.

There is a product that is mounted between a meter panel and the panel. Its called Generlink. Some utility companies up my way install them. They have 30 and i believe 50 amp versions. Its a nifty idea.

 

[JerryK]

I have been using the back feed method for using a generator since time began. I currently have a sliding face plate type interlock on my 200 amp barn panel. Any competent person can back feed a panel, but you have to admit there are those among us that do not pass this test 24/7, especially in the odd times the power seems to always fail. There are also times that you might not be around, and your significant other might attempt to get the juices flowing and get into trouble. So an interlock of some type is not a bad thing. Can't make things 100% safe, but the electrical code is written to try to reach that goal. I ...IS... a retired person that was once extremely well paid to do electrical work, so your results may vary.....

 

[check]

My electrician installed a 60 amp generator subpanel when we built the cottage back in 2002. Since we only had a 6500/5500 portable generator, we only put a certain number of important circuits in that subpanel. Of course it contains a simple mechanical device that forces you to shut off the power from the main panel while at the same time turning on the power from the generator that is plugged in outside. Very elegant, and very simple.

Now we have a 17 kW Propane standby generator, with an automatic transfer switch to power the whole house. However, if that generator ever fails, we can always plug in the portable one and still have power for essential circuits.

Despite the fact that the electricity company has upgraded huge amount of the infrastructure, we get regular power outages. Thank God for generators!

 

[MossRoad]

And one can always put twist-lock plugs on their furnace, well pump, etc.... and power things with extension cords in a pinch by just unplugging them and plugging them into the cords. Just run the cords through a window and close them up. Shove a towel in the crack if it's cold out or to keep the bugs out, etc... and keep the generator exhaust away from the house, not in a garage, etc....

There are so many deaths by carbon monoxide poisoning and generators each year. Be safe.