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Author Topic: Where to bond Ground with DG and other Q's  (Read 5658 times)

Stephen Swaffer

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Re: Where to bond Ground with DG and other Q's
« Reply #20 on: April 12, 2015, 03:03:10 pm »

Bonding prior to the TPN would be best-you don't want your bond disconnected when the TPN is opened.

As discussed earlier, it would be best if there were 5 wires between the genny and your distro.  Lacking that, there should be a bond at your distro as well as at the genny; ie, the neutral should be bonded to the genny frame-otherwise a fault there can potentially raise the genny frame above ground potential creating a shock hazard.

Is there over current protection at the genny?
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Steve Swaffer

Keith Broughton

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Re: Where to bond Ground with DG and other Q's
« Reply #21 on: April 12, 2015, 03:20:51 pm »


Also, in 3phase systems, what happens if 2 live phase cables were to come into direct contact ?
Things would get very exiting! :o
There is 208 volts between phases so, yes, you would very likely trip the 3 pole breaker.
Probably some melted stuff to clean up as well .
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Frank DeWitt

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Re: Where to bond Ground with DG and other Q's
« Reply #22 on: April 12, 2015, 06:26:17 pm »

Edison didn't invent the light bulb.  What he set out to do, and did was invent a system that would make home electric lighting less expensive and better then the gas lighting used at the time. To do this he improved the light bulb to the point that it gave off a reasonable amount of light and lasted a reasonable amount of time.  He added to this the light base and socket, the fixtures, the wiring methods. switches, fuses the distribution system, the 3 wire shared neutral system among other parts of a home lighting system. He also hired and trained electricians to install all this and set up manufacturing plants to drive down the cost of light bulbs.

He got the AC DC thing very wrong no doubt about it he also didn't think to invent outlets for appliances.  Overall he got a lot right and we all have benefited from it.
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Nitin Sidhu

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Re: Where to bond Ground with DG and other Q's
« Reply #23 on: April 13, 2015, 03:01:49 am »

Bonding prior to the TPN would be best-you don't want your bond disconnected when the TPN is opened.

As discussed earlier, it would be best if there were 5 wires between the genny and your distro.  Lacking that, there should be a bond at your distro as well as at the genny; ie, the neutral should be bonded to the genny frame-otherwise a fault there can potentially raise the genny frame above ground potential creating a shock hazard.

Is there over current protection at the genny?

Thank you Stephen!

Yes, all gennies that I have come across have the frame bonded, and yes, they do have over current protection.
Im still trying to visualise the impact of the bonding at our distro prior to or after the TPN... Could you help me out here.. If the TPN is open, how would it make a difference ?
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Stephen Swaffer

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Re: Where to bond Ground with DG and other Q's
« Reply #24 on: April 13, 2015, 08:17:57 am »

If you had a phase to ground fault in the distro before the TPN (however unlikely, but it does/could happen) that fault should cause the TPN/OCPD to open.  If the bond is after the TPN and it opens, then you no longer have a path for the fault current, but your distro box would be energized or "hot".  With the bond before the TPN, the only way to clear the fault is for the OCPD at the genny to open-this removes power from your phase conductors preventing your distro from being a hazard.

If the bond is after the TPN, you might get lucky and the have breaker in the genny trip anyway-it all depends on the trip characteristics of the individual devices.  It is obviously best not to leave safety up to chance.
« Last Edit: April 13, 2015, 08:33:14 am by Stephen Swaffer »
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Steve Swaffer

ProSoundWeb Community

Re: Where to bond Ground with DG and other Q's
« Reply #24 on: April 13, 2015, 08:17:57 am »


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