Are you sure it is disconnected, best to verify with a meter.
Breakers can fail closed or open circuit.
Question on generator hook up to meter
- Thread starter rcems2000
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Breakers can fail closed or open circuit.
I completely remove the main from the breaker housing BP.
Is that safe?
I see a gap of several inches to prevent back feed.
Please let me know if I'm Afu!
Your main breaker is bolted to the 240V mains on one side and the panel on the other. Lot of work to do that. An interlock is once and done.
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Interlock device is an absolute necessity imo, otherwise it’s easily possible to send voltage back through the meter and onto the commercial power lines and kill a line tech or even a normal person if the line is downed, and that transformer hanging off the pole in your front yard or in that cabinet in the corner of your lot? It works both ways, takes 7200v down to household voltage (240/120) and when 240 hits it from the downstream side (your house connection) it bumps it to 7200...
OK, yes, this will work. Cheap, too. But as you said, kids, don't try this at home. I see lots of houses where they have an outdoor plug for a generator wired to a backfed breaker too, but in addition to endangering the linesman who is out there trying to get your power back on this has it's own set of problems. If they forget to turn off the generator breaker after power comes back on that outdoor plug is now hot, and just waiting for some curious kid (or dimwitted adult) to come along and get themselves zapped.
When we rewired this house about 15 years ago I had a separate generator panel with a manual interlock installed, and it has worked fine. Yes, I do have to turn off any circuits I don't absolutely need, and even with an 8,500 watt portable generator I have to be careful about running the well pump and water heater together, but it was pretty easy to do.
I'm running on generator power right now (thanks to the recent ice that downed trees in northern NC this Valentine's day weekend) by way of a 50amp breaker using a manufacturer-made interlock in support of a 12kW/15kW running/startup (respectively) portable generator using 6AWG copper service rated wire across a 65' run. I could have done the installation but had a licensed electrician do it mostly as a matter of buying some peace of mind in the event something went wrong after the installation.
Something important to note -- when using an interlock, NEC apparently requires that the generator breaker be secured in the box using a retaining strap. NEC doesn't specify how, so an appropriate zip tie (used as a retaining strap) will technically meet code for the breaker retaining strap requirement of NEC Article 408.36, though the electrician I used mentioned some inspectors will not pass that unless you know enough about code to push the issue with them. In my case, because I was using a manufacturer interlock, it came with a means of securing the generator breaker to a retaining strap with a screw, so it was no big deal ... but when I was looking for an interlock for my panel I came across several non-manufacturer devices for my panel that did NOT provide such a means or mention the need to do so ... hence why I am mentioning it, here.
Also worth noting is that I looked (and looked ... and looked) for a manufacturer interlock device for my panel because I wanted something UL listed. Key to this is that some inspectors won't pass third-party interlocks since they tend not to be UL listed. This is one reason people might avoid third-party interlock kits ... and also a reason one might avoid making one on one's own. Ultimately it's up to the inspector to decide if field modifications are acceptable in situations such as this, so if you want something that can't be ding'd, go with a manufacturer-made interlock kit that is made for your panel (assuming that's possible; some panels are too old, I know).
Oh, and while copper wire is expensive, the ampacity of aluminum wire is so much lower than that of copper that it must be up-sized to do the same job. For wire going from your generator inlet to your panel, stick with copper if you can afford to; you'll be glad you did. For context, according to the NEC (NFPA 70) Table 310.15(B)(16), 6 gauge copper circuit rated at 90°C (194°F) has an ampacity of 75 amps while a 6 gauge aluminum conductor rated at 60°C (140°F -- i.e. MUCH cooler temp!) has an ampacity of a measly 40 amps. My copper wire stays nice and cool at max load, but boy did it heat up my wallet to buy it.
I hope someone finds some part of the above useful ...
Surreal
P.S. I am NOT an electrician. I did not stay at a Holiday Inn Express last night, either.
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Aardvark
Identifies as okie-dokie
Westinghouse 12kW running / 15kW startup portable generator implementation details...
- Exhaust has been customized and routed into 4"x3" aluminum downspouts (routed as upspouts and sealed at all joints with 500F rated silicon) to bring CO emissions 2' above roofline of home
- Exhaust is piped from this walkout basement level to above roofline where it turns to preclude water entry; it is also screened to preclude bug entry
- Base of 4x3" downspout is packed with steel wool where flex tube enters to keep out bugs
- Exhaust temp at flex tube tests ~450F; 2' up 4x3" downspout after flex tube enters this is ~350F, and there is loss of about 100F per 2feet thereafter until we reach ~150F, which is the temp the aluminum downspout remains all the way to exhaust exit
- Exhaust is around stone when it's hot enough to worry ... and by the time it gets near anything worrisome like siding, aluminum is such a great medium for heat exchange that it's done it's job and there's no worry; aside from the snorkel, the downspout looks pretty normal/natural
- Solar panel with built in trickle charger (seen in photo with generator exhaust pipe above roofline) faces south and keeps generator's starting battery topped off
- CO levels around the generator measure between 7-9ppm with no wind; less in a mild or higher breeze; measurements inside the basement (there's a 4x6' casement window within 2 feet of the generator) measure 0ppm, and I have a CO alarm there, as well
- 6AWG copper service rated wire to panel from inlet using dipole 50amp breaker with interlock kit
- Panel stickers provided by manufacturer applied to panel
- Panel door has a sticker indicating location of generator; there is a matching one on the meter outside
- Powerback alarm unit installed just above panel; I activate it when I switch over to generator power; it uses an induction wire wrapped around one of the grid power leads to the main breaker to sense when power returns and sets off a 140+ decibal chirping alarm that can be heard throughout the home to let me know when power is restored
This year I hope to do a custom, forced-air enclosure for the generator that's sized for the space. I've been studying the Zombie Box units and understand how they function (including their airflow design), I just need to sit down and do the design work for my space, heat output, etc., as I want something that matches my need. The Zombie Boxes are built with portability in mind, and my need is for a permanent fixture, so I need doors ... and a lid with gas-shocks, because I want refilling to be easier than it would be with a Zombie Box. I also think there's room for improvement on their sound deadening approach -- specifically I intend to use 2" foam material that's used on aircraft firewalls, as it's lightweight, heat-resistant, and very soundproof. (I've used a 3/4" version before as a hoodliner; it's VERY effective in terms of both heat and sound mitigation.)
Surreal
P.S. I wanted my generator under cover so that I'm not refueling it in snow, ice, rain, etc. Generator tents wouldn't cut it and my lot isn't conducive to putting it anywhere else that's covered. So, it's right next to the house against all of the usual safety advice. However, it's next to stone ... which isn't going to ignite ... and sparks and the like are going into the exhaust system. So, unless the generator, itself, catches on fire, the only risks I'm facing is CO -- which I've taken great care to mitigate, measure, and guard against. (CO is the reason generators are typically advised to be 20 feet from homes.)
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Nice setup @surrealone
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I never knew that PowerBack alarm existed...always thought it would be nice to have something like that, either an audible alarm or a flashing light. Never stopped to do a search for anything. Might have to do some investigation to see what other options exist as well.
Before I got the Generac I had a portable generator that I ran different things in the house. It would not run the AC or range. What I did was have a heavy 220 wire made where I could plug it in the generator and the other end I plugged into my dryer 220 outlook. Before doing this, you HAVE to turn off the main breaker coming into your house so you do not kill any line man working on the lines. Right after I cut off the main breaker, I would turn off all the other breaker except the 220 breaker that went to the dyer. By doing it this way (back feeding your panel) I could direct the power to what ever room I wanted to have power by turning on that breaker. I could run fans, lights, charge my cell phone and watch TV using an antenna.
If you elect to do this, REMEMBER TO CUT OFF THE MAIN BREAKER BEFORE HOOKING UP ANYTHING.
If you elect to do this, REMEMBER TO CUT OFF THE MAIN BREAKER BEFORE HOOKING UP ANYTHING.
Might be a help for an electrician member to write up the steps for running a portable generator through a transfer switch.