Pre Purchase MEP 710a questions

[212sparky]

Part of the problem with grounding is it is NOT a simple issue, and depends on a lot of details for how you do it and still be code compliant even if the basic concept is fairly straight forward, in addition the NEC code as it relates to generator installation has been extensively revised in the last 10-15 years at least 3 times, so what was code legal 10 or 20 years ago may not be today. As a result even many electricians that install generators from time to time get things wrong when it comes to this part of the electrical code.

Having said that if you are going to run a completely separate system that does not connect to your home power system and you will just move the plug over to the generator powered only outlet in the event of an outage things should be fairly simple, as this is basically the way the army intended these units to operate in "island mode".

If all of your outlets that you plan to power are 120VAC, here is how I would do it:

(someone correct me if there is a code violation I missed, as I don't do this for a living)

I would drive a ground rod at the generator, and have the neutral ground jumper installed and connect the generator to the ground rod and set the generator for 120V single phase only

then use a length of cord on the generator with an twist lock L5-30 receptacle (cheapest way to get is probably an L5-30 extension cord (120V only 3 wire 30 amp twistlock) and cut off the plug end and wire this to the output lugs, L5-30 cords are commonly used for marine / boat application in marinas, and finding cheap used ones with damaged plug ends is fairly easy, you just need one with a bad plug and good receptacle, 25 or 30 ft are the most common lengths)

Get an L5-30 inlet box and mount this on the side of the house, from this I would feed a small 6 or 8 circuit main breaker pane with an appropriate number of 15 or 20 amp breakers running to each dedicated generator only outlet.

Total investment cost probably under $200 + wiring cost. $50-75 for a used 30 amp marine cord, $30-$40 for the inlet box, another $50-$75 for the small (60 -70 amp) breaker box and breakers, add in 4 or 5 15-20 amp outlets at $5-$15 each depending on if they are GFCI or not, most places require GFCI for all outlets in living spaces as of the latest NEC code, excluding refrigerators due to chance of false tripping when connected to compressors.

Sounds like the best route to me to do what he is looking to do. You can also get red or orange recepticals so at a quick glance can tell what it is, easier to explain to some one what to do.

 

[alphamale]

Ok, first and foremost, thank you and everyone else.

The white wire I mentioned is in place.

I never thought this forum should address code, you seem very well versed on the machine and my question was about the machine. Certainly my attempt to start a conversation using photos seemed an easy start. But in the end I have my answer and I bet the basics have not changed in 30 years. I find it odd how the manual and conversations people have about these fine old machines don't address "guidance for connecting the equipment grounding conductor" That's a pretty important aspect in the most basic of forms. Its hard to articulate the question unless you understand a little more than I do. But, I got her done.

 

[tim292stro]

Agree with Issac-1 about the issues with Grounding. NEC is still fighting with this issue to this date - the most concrete answers you will get are for permanently installed generators. Circuit ground-wires (equipment-grounds) and the panel ground-rod (system ground) are oft mis-understood wires in an electrical system - and they serve two completely different functions. I'll let Mike Holt do the explaining:
https://www.youtube.com/watch?v=xn4az8EuNO0


The part I'd differ with is the rating of those breakers you electrician installed - for a 3kW 120V generator, you're only looking at 25Amps of service, two 50Amp breakers won't do a lick of good protecting that generator (their purpose). A single 25A breaker feeding a dedicated generator panel would be the way to go. Drive a ground rod at the generator, do a system ground at the generator, bond the neutral to the ground at the generator, run a 30Amp plug to the house (Hot, Neutral, Ground) L5 is a twist-lock 125V connector (L5-30 is the 30Amp size of that plug/receptacle). The regular house and generator circuits should not interconnect anywhere if you go this route.

If you want to tie it into existing circuits in your home, you need a transfer switch between the main electrical panel and the emergency power sub-panel, and you'd have to rely on the ground/bond at the house (remove the ground/neutral bond at the generator). There is only one ground/neutral bond allowed in a system adding another bond by accident or on purpose makes the ground wires (equipment ground) part of the neutral circuit (BAD).

Issac-1, GFCIs are required in the Kitchen, Bathroom, Garage and Outdside. Inside, AFCI are required in all other circuits - but only if the newest NEC is adopted in the specific region.

I'll also be the one to say it - pull a permit with your authority having jurisdiction before doing any of this.