Portable generator question

[jwelectric]

What is FTCN?

From the UL White Book


ENGINE GENERATORS FOR PORTABLE
USE (FTCN)
GENERAL
This category covers internal-combustion-engine-driven generators rated 15 kW or less, 250 V or less, which are provided only with receptacle outlets for the ac output circuits. The generators may incorporate alternating or direct-current generator sections for supplying energy to battery charging circuits.
When a portable generator is used to supply a building or structure wiring system:
1. The generator is considered a separately derived system in accordance with ANSI/NFPA 70, ??National Electrical Code?? (NEC).
2. The generator is intended to be connected through permanently installed Listed transfer equipment that switches all conductors other than the equipment grounding conductor.
3. The frame of a Listed generator is connected to the equipment grounding conductor and the grounded (neutral) conductor of the generator. When properly connected to a premises or structure wiring system, the portable generator will be connected to the premises or structure grounding electrode for its ground reference.
4. Portable generators used other than to power building or structure wiring systems are intended to be connected to ground if required by the NEC.

I have an old 5kw portable where the owners manual shows a diagram and a picture or a 15R male plug with a jumper from ground to neutral to be used if a neutral is required if using the 240 volt receptacle. The Generac home generators have the "floating" neutral because they use a two pole switch.

I have a building in my yard that only has a three wire feeder so I suppose should I decide to install another feeder to another building three wires is all I will need to install? I don't need to look at 250.32 of the current cycle of the NEC just because I already have one like this?

I found a Honda service bulletin on line dated August 2003. It suggests corrective action for removing the N-G bond when connected to premises wiring. See below:

And this means that there has not been any changes to either the listing requirements or the installation requirements for the past 8 or 9 years and even if there has been then the new requirements don't count?

Using the line of thought of the group here on this site all one would have to do to have a compliant installation is find something somewhere in the past that would have allowed the installation and use that information to make an installation today.
Hey I just found a document that allows the installation of tubes through floor joist for single strand conductors. Does this mean I can use this document to make the installation of Knob and Tube today?
Then why is everyone pulling up documents from years gone by to back something being done under the 2011 code installation.
I bet it is because no one likes change

 

[don_resqcapt19]

Mike,
I think you are missing the points in this discussion.

The first one is that if you have a generator without a neutral to frame bond, there is no requirement that the transfer switch switch the neutral. As far as if that type of generator should exist is not part of the discussion. While the standard for generators requires this bond, that only applies to a manufacturer who wants to get his product listed. There is no requirement that a generator be a listed product. You make the installation based on the product you have. If the neutral is bonded, then you use a transfer switch that switches the neutral. If it doesn't you don't

The second part of the discussion is about the technical merits of making sure that there is no parallel path for neutral current. Given that there are code required parallel paths for grounded conductor current on the line side of the service disconnet, I really don't see an issue for parallel paths from a small portable generator. I fully understand the code says we can't have those paths, but that does not mean we can't debate the merits of the code rule.

 

[Bernard1599]

And this means that there has not been any changes to either the listing requirements or the installation requirements for the past 8 or 9 years and even if there has been then the new requirements don't count?

Using the line of thought of the group here on this site all one would have to do to have a compliant installation is find something somewhere in the past that would have allowed the installation and use that information to make an installation today.
Hey I just found a document that allows the installation of tubes through floor joist for single strand conductors. Does this mean I can use this document to make the installation of Knob and Tube today?
Then why is everyone pulling up documents from years gone by to back something being done under the 2011 code installation.
I bet it is because no one likes change

I am afraid that you read too much into my posting of the 2003 Honda service bulletin. I was not implying that there were not any changes in the code or installation guidelines since then nor of their merits. I was not arguing a point made by you or anyone else. I was merely showing a possible solution to my original question in Post # 1.

Regards,
Bernard

 

[kwired]

Wouldn't this mean that there would now be a difference in potential of 240 volts?

Voltages between output leads do not change just because you grounded a different lead. If you ground L1 you will still have 120 volts to N and 240 volts to L2. Voltage to ground will be zero on L1, 120 on N, and 240 on L2. Everything connected to generator frame and other EGC is still zero to ground. Introduce a second fault and you will be opening overcurrent devices - which is part of what they are for.

... there is a possibility of a 240 volt shock if there are two different faults at the same time. However if the circuits being used are 120 and GFCI protected, a shock caused by the two faults would trip the GFCI. As far as having 240 on the equipment, the equipment itself, will only see 120, no matter what conductor is bonded. The issue is the possibility of a 240 volt shock if the second conductor would fault.

Two faults to ground at same time only results in risk of 240 volt shock for the duration of time it takes for the overcurrent device to open. Similar situation exists is the neutral is the grounded conductor.

 

[jwelectric]

Mike,
There is no requirement that a generator be a listed product.

Should one be in an area that has adopted the IBC then there is a requirement that any generator be listed, see Chapter 27

Now we are back to FTCN on page 151 of the 2011 UL White Book

 

[don_resqcapt19]

Mike,
The IBC reference requires a listed stationary generator listed to UL 2200. The UL white book info that you have posted is for portable generators listed to UL 2201. The rule in Chapter 27 of the IBC, also only applies to emergency or stand by power systems that are required by the IBC or the International Fire Code. I don't believe that the installations being discussed in this thread are installations that are required by either code.