Portable Generators - The Elephant in the Closet

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JPinVA

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Begin Rant.

I've been doing a lot of "in the weeds" look at portable generators lately. I'm talking the small ones...8KW or smaller...with one or two 120V receptacles and perhaps a 240 30A L14-30.

I've looked at the NEC, UL, and OSHA. I've explored various manufacture's Q&A on grounding/bonding, their instructions, and a good bit of posting on forums such as this as well as some technical sites.

They are ALL eff'd up in one way or another. There are so many things I just can't bring myself to list everything wrong or misleading, or convoluted to the point of incomprehensible. But EVERY ONE has some flaw.

Most of us here are technically inclined. Professionals. God help average Joe Generator. Navigating a simple answer is nigh impossible.

The silver lining in all of this. As eff'd up as the explanations (and requirements and regulation) are, the raw configurations of our portable generators provide at least one layer of fault protection from electrocution. And if GFCI's are employed, there are actually two layers of protection. The bonded neutral/ground generators will clear equipment faults via the EGC. Floating neutrals, while not able to clear a fault, require a second fault to close the loop. Ironically, in the latter case, a ground rod is actually MORE DANGEROUS, as it aids the closing of the second fault loop. Yet OSHA requires one for a Float Generator!!? But I digress.

The reason the small portable generators are 'safe' when used properly is not because of the mush of instructions, guidance, and regulations that one must follow to make them safe. They are safe because they are safe (if used properly)...out of the box.

I'm not really asking a question. Just ranting. Ranting that NEC, OSHA, (I'll defer UL for the moment) are crap when it comes to small portable generators. Add to that the crap from manufactures instructions, and their help sites, and the myriad "tech" websites.

Rant Over. Carry on.
 
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tom baker said:
Suggest you review the ROP and ROC for the 2014 NEC in Art 450 regarding GFCI protection for generators
Click to expand...

Thanks. I'll take a look.

Here's my logic following one situation. A small portable gen with floating neutral connected as a non-SDS is one of the simplest, safest, and economical configurations. No ground rods. No additional GECs. No separate connection to a GES. GFCIs on the gen work fine. Gen EGC (for Gen faults) work fine.

But that simplest, safest, economical configuration is IMPOSSIBLE to implement with ANY listed equipment in an NEC code compliant way. Not 99% impossible. 100% impossible. Why is this? Because a listed gen less than 15KW MUST HAVE A NEUTRAL/GROUND bond in the generator. Once we go there, NEC requires a switched neutral at the TS to avoid two neutral/ground bonds. And once we go there, NEC now requires a GES connection...either with a rod at the gen (ahem! Talk to Mike about rods at generators) or a connection to the existing structure's GES....which, if we follow the carbon monoxide safety protocol, can result in a rather lengthy cable...but doesn't NEC say long cables are bad for a GES connection?

So....we've gone from a simple, safe, economical situation to a complex, convoluted situation that (based on the NEC itself) results in GES connections that are of questionable effectiveness at best.

I understand the root of this problem. The use of small gens as standby power without connection to a structure and the OSHA mandate (and UL's listing requirement) for bonded neutrals (to maintain a ground fault path for connected equipment). But there must be a better way than to sacrifice the simplest, safest, and economical non-SDS configuration on the alter of stand-alone direct connections.

In fact, one might argue that the neutral/ground bond and GFCI mandates might, for the DIY, create a significant safety issue. An N/G gen with GFCI, connected to a DIY non-SDS TS, will result in the GFCI's tripping on the gen due to the parallel EGC path back to the Gen. This connection is not NEC compliant due to the parallel path. Some manufactures provide the option of disconnecting the gen's N/G bond. While this removes the parallel path, and the GFCI's work, now the gen has lost its listing. Do we really want DIY pulling bond wires off gens?

Or, perhaps the really bad solution for the GFCI trip. Just leave the EGC from the 14-30 open at the inlet. Yes, this is a major code violation. But it solves the GFCI's trip problem. It also removes the ground fault clearing path for the ENTIRE STRUCTURE served by an SDS system. The DIY has just made the entire structure unsafe...but the GFCI's on the gen work fine!!!! Do we really want to offer the DIY this option to fix his/her GFCI problem. This is not an issue with a non-SDS gen configuration. In fact, even if the gen EGC somehow got disconnected at the inlet (or anywhere at or between the gen and SE), the EGC fault clear path of the structure served by the non-SDS would still work perfectly.

In our quest for small gen job site safety (direct plug connect), I fear the gyrations we must go through to make the same generators "safe" (compliant) for TS connections create other safety issues. The simple, safe, economical listed non-SDS solution should have a place in the NEC. Today, it does not.
 
JPinVA said:
...
But that simplest, safest, economical configuration is IMPOSSIBLE to implement with ANY listed equipment in an NEC code compliant way. Not 99% impossible. 100% impossible. Why is this? Because a listed gen less than 15KW MUST HAVE A NEUTRAL/GROUND bond in the generator. Once we go there, NEC requires a switched neutral at the TS to avoid two neutral/ground bonds. And once we go there, NEC now requires a GES connection...either with a rod at the gen (ahem! Talk to Mike about rods at generators) or a connection to the existing structure's GES....which, if we follow the carbon monoxide safety protocol, can result in a rather lengthy cable...but doesn't NEC say long cables are bad for a GES connection?....
Click to expand...
Very few generators of that size are listed and there is nothing requiring you use a listed one when connecting it to a building or structure. Just use the non-listed ones and not switch the neutral.
 
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