texie
Senior Member
- Location
- Fort Collins, Colorado
- Occupation
- Electrician, Contractor, Inspector
Funny, I just looked up the same thing before I saw your post and saw the same result. What gives?
stand-alone generators
- Thread starter jwelectric
- Start date
- Status
Funny, I just looked up the same thing before I saw your post and saw the same result. What gives?
- Location
- Illinois
- Occupation
- retired electrician
I don't think they exist. There is no rule that requires a generator to be a listed product, so why would a manufacturer spend the money to get on listed?
jwelectric
Senior Member
- Location
- North Carolina
According to Mike Holt in the comments he made to the newsletter that started this thread Honda made a deal with UL so based on that statement I would say that UL must play some role in the manufacture with some generators.
I would also think that a stand-alone of self-contained generator that could be used for temporary power as outlined in 590 of the NEC would be required by OSHA to have a third party listing also.
With the influx of the small multi circuit transfer switches that also switch the neutral to the market there must be something to this UL FTCN, see Eaton?s Instruction Booklet IB 70-8704 for SDS and non-SDS transfer cord and plug connected manual transfer switch
I would also think that a stand-alone of self-contained generator that could be used for temporary power as outlined in 590 of the NEC would be required by OSHA to have a third party listing also.
With the influx of the small multi circuit transfer switches that also switch the neutral to the market there must be something to this UL FTCN, see Eaton?s Instruction Booklet IB 70-8704 for SDS and non-SDS transfer cord and plug connected manual transfer switch
- Location
- Illinois
- Occupation
- retired electrician
As far as a can tell Honda does not have a UL listed engine generator.
I think you are correct that OSHA does require the use of listed equiment where such equipment exists. I don't find any UL listed engine-generator sets. Is this a new standard and no one has listed to it yet?
I am not sure that has anything to do with the information in UL FTCN....it would be my opinion that the transfer equipment has been designed so that you can make a code compliant installation. I don't see how UL FTCN has anything to do with an installation that does not involve a generator that is not listed to UL 2201. As I said before the code rules apply no matter if the equipment is listed or not. The code rules require the transfer switch to switch the neutral if the generator is SDS. There is no need to look to other documents.
I am still not convinced that there is any real world safety issue with not switching the grounded conductor when a small engine generator is used to power a building via a transfer switch. Yes, it is a code issue, but it can't be a real serious issue as this is one of the areas where the NEC tries to tell us that the electrons behave differently based on what side of the meter they are on.
jwelectric
Senior Member
- Location
- North Carolina
Would you say that the bonding in both the secondary side of a transformer and then again in the panel it supplies with another path such as the supply side bonding jumper or metal raceway posses a safety issue?
I see the two as the same
I see the two as the same
- Location
- Illinois
- Occupation
- retired electrician
Mike,
The larger the current source the bigger the hazard, but in general there is not a serious hazard unless you have an open neutral connection.
However keep in mind that multiple paths (and that is what we are talking about here) for grounded conductor current are required by code rules on the line side of the service disconnect. That is safe, but as soon as we have multiple paths on the load side of the service disconnect, that is not safe:?
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
What is "FTCN"?
- Location
- Illinois
- Occupation
- retired electrician
It is the category in the UL White Book for "Engine Generators for Portable Use".
- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
Thanks!
Only thing I could come up with was:
FTCN=Fixin-To Connect Neutral :lol:
north star
Senior Member
- Location
- inside Area 51
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I thought that the NEC was the NFPA! :blink:
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I thought that the NEC was the NFPA! :blink:
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jwelectric
Senior Member
- Location
- North Carolina
I am not understanding what you are saying in the underlined part above. To keep it simple let's use a residential single phase service with two hots and one neutral. Where are the multiple paths at in one of those?
- Location
- Illinois
- Occupation
- retired electrician
Around here all services are in metallic raceways. The conduit between the meter can and the service disconnect will be in parallel with the grounded conductor.
If you have TV cable, the shield will be in parallel with the grounded conductor, via your neighbors bonding connection. I have seen two fires that have resulted from this required parallel path when the service neutral was lost at the pole and the neutral current was running on the TV cable bonding conductor.
In areas with common metal underground water piping systems, the water piping is in parallel with the grounded conductor, again via your neighbors bonding connections. It is not uncommon to see 25% or more of the grounded conductor current flowing on the water pipe when you have a common metal underground water piping system. This happens even when there are no connection problems with the neutral. If there are problems with the neutral, more current will be on the water pipe...maybe even all of it. This NEC required parallel path creates a serve hazard for anyone cutting the water pipe between the GEC connection and the water pipe street connection if there is an open neutral. It is not a big hazard to the plumber if the neutral has no connection problems.
If you have an underground phone line, the shield will be bonded at your house and at other house creating another parallel path for grounded conductor current.
These are all code required parallel paths for the service grounded conductor current. Based on these required paths, I see little danger in a parallel path from having the neutral of a stand alone generator bonded at two locations. There is no question that there would be a code violation, I just don't see the danger.
jwelectric
Senior Member
- Location
- North Carolina
Those things you have outlined above are in fact things that we face today but they are not due to a compliant installation that is installed correctly.
The issue has to do with making such an installation where parallel paths are done deliberately.
If the fact that having it bonded at both places was not enough danger the mandate that all 120/240 volt 30 amp and smaller receptacles must be GFCI protected will prevent it from happening.
The issue has to do with making such an installation where parallel paths are done deliberately.
If the fact that having it bonded at both places was not enough danger the mandate that all 120/240 volt 30 amp and smaller receptacles must be GFCI protected will prevent it from happening.
- Location
- Illinois
- Occupation
- retired electrician
The electrons have no idea if the parallel path is permitted by the code or prohibited by the code. Either they are safe or they are not safe, but there is no way that they are safe on one side of the service disconnect and dangerous on the other side.
As far as having the GFCI protection on the receptacle, yes that will prevent the use of a cord and plug connection to a building via transfer equipment that does not switch the grounded conductor. However, there are generators out there with the required GFCI protection that do not have the neutral bonded at the generator. These will work just fine with transfer equipment that does not switch the grounded conductor.
- Location
- Massachusetts
What was non-compliant or incorrect about the installations he described?
Are we not required to bond the cable coax shield?
jwelectric
Senior Member
- Location
- North Carolina
to iwire Yes but when everything is working as it is supposed to work then there is no danger in the bond to the earth ground. It is not until there is a problem with the connection to the midpoint of the supply that anything goes wrong.
With the generator bonded at both places we are intentionally installing this parallel path which is against the very scope of the NEC.
With the generator bonded at both places we are intentionally installing this parallel path which is against the very scope of the NEC.
jwelectric
Senior Member
- Location
- North Carolina
I have both Telephone and Cable bonded to the grounding electrode of my service equipment whiteout any problem. Under normal operation this is a safe and compliant installation. It is not until something abnormal happens that there is a danger to the installation.
The installation in and of itself does not constitute a parallel path back to the supplying transformer. When the neutral gets disconnected then we have a very bad situation.
When the neutral is not bonded to the frame of the generator and there is a fault of one leg to the frame there is nothing to clear this fault. Should this fault be between the windings and the GFCI device then we have a very bad situation.
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- Location
- Massachusetts
- Location
- Illinois
- Occupation
- retired electrician
This is exactly the same with the parallel path created when a generator is used with transfer equipment that does not switch the neutral and where the generator has the grounded conductor bonded to the generator frame. There is a parallel path that does not really cause any problems unless you have some type of issue with the grounded conductor between the generator and the building.
I don't see how it doesn't create such a path. It is bonded the grounded conductor at your house and and every other house in the area. How is that not a parallel path?
In an isolated system this single fault would do nothing more than create a grounded system. In the case of a generator supplying power to a building via transfer equipment that does not switch the grounded conductor, there will be fault current. If the fault is between the windings and the line side of the GFCI, the amount of fault current will only be slightly less than if there was a direct bond to the frame of the generator. This would be because the fault current has to travel a longer path. It would travel from the faulted leg to the main bonding jumper via the EGC. The lack of a bond does not change much here.
The same thing happens for a fault on the load side of the GFCI where there is no neutral bond at the generator. In either case, the only thing that is likely to clear the fault would be the prime mover stalling. It is very unlikely, even with a solid fault, that the generator can source enough current to trip a breaker quickly.
Of course, if there is a neutral bond at the generator and the fault is on the load side of the GFCI, the GFCI will clear the fault very quickly. And yes that is safer.
- Location
- Illinois
- Occupation
- retired electrician
We are not debating the code requirement. It has been repeatly stated that the bonding at more than one point is a code violation.
As far as the parallel paths they are intentionally installed in both cases....in one case they are required by the code and in the other they are prohibited by the code.
I still don't know how the electrons know to behave nicely when the parallel path is code required and to misbehave when the parallel path is a code violation.
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