Portable E-gen Fiasco?

H U G G Y

Member
I was asked by my best friend to look at a proposed portable E-gen set-up for a 2 year old county maint. garage. This garage has a single phae 400a main brkr panel w/42 ckts. While looking at the "set-up", I saw they had all ready installed a 100a pin recept. outside, back wired into a Ronco manual 2p transfer sw. This manual Xfr fed into the single phase 400a main panel. I then began to point out a miriad of problems to him. Please correct me if my concerns are not warranted. 1. This is a manual XFR-SW, no automatic way of POCO isolation, unless you knew to manually open the 400a main brkr.( I assume the E-pwr was wired to the load side of main brkr ) 2. No LOTO of any kind on the XFR-SW or Main, to prevent the obvious. ( as it sits now, if the XFR-SW was thrown,it would pass the entire main, to the pins of E-GEN recept. ) 3. No posted SOP for E-gen procedures. No labeling of any kind, nothing listed in the panel directory for what the E-PWR feeds, (assume the entire panel) 4. Should'nt there be a brkr on the 100a E-pwr wiring, supplying the main panel? (the conduit run is about 5' and these conductors are not protected, if a short would occur). I have not seen the E-GEN yet. But it is only 20kw, 50a. This all-ready long enough, but I want to help my friend.... I told him he should contact the original EC, for any other inquiries/shortcomings. I feel the EC was in this project for quick government $$$. This facility was overbuilt, has room to expand, no extra ordinary life safety demands/requirements other than it being a county/gov't bldg. The load demands of this facility are really low. I think the well pump & door operators are the largest loads, outside a welding recept. Thank you for reading..... PleaseTell me that the sky is not falling
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
Using your numbers:

1. Automatic or manual doesn't matter. I wouldn't make that assumption.

2. The T/S is wired incorrectly if the utility and genny can be connected.

3. Again, you should inspect the entire installation, not assume anything.

4. The generator should come with its own built-in output-circuit breaker.
 

PaulMmn

Senior Member
Location
Union, KY, USA
You say the generator feed goes into a transfer switch. Does the POCO feed also go into the TS, and the output from the TS to the 440a main breaker panel? If so, that means that only 1 power source can hit the main breaker at a time.

As Larry says, 3) inspect everything, assume nothing.
 

H U G G Y

Member
Using your numbers:

1. Automatic or manual doesn't matter. I wouldn't make that assumption.

2. The T/S is wired incorrectly if the utility and genny can be connected.

3. Again, you should inspect the entire installation, not assume anything.

4. The generator should come with its own built-in output-circuit breaker.
The T/S is wired into the main brkr panel......I assume to the LOAD side of the main brkr. Was not allowed to visually inspect. Strange that the E-feed would not be back wired through a separate brkr, there by providing a more assured way of isolation from the POCO,and then properly identified as such in the panel. As the system stands now,/normal operation, If the T/S were to be thrown, 400a of main power would be present at the pins of the E-GEN plug.
 
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H U G G Y

Member
You say the generator feed goes into a transfer switch. Does the POCO feed also go into the TS, and the output from the TS to the 440a main breaker panel? If so, that means that only 1 power source can hit the main breaker at a time.

As Larry says, 3) inspect everything, assume nothing.
POCO feeds a 400a 42ckt singlephase panel. T/S is wired into same panel ( i assume to the load sideof main brkr ) could not visually inspect the connection.Nothing labeled in panel to indicate a seperate E-gen feed.
 

PaulMmn

Senior Member
Location
Union, KY, USA
The T/S is wired into the main brkr panel......I assume to the LOAD side of the main brkr. Was not allowed to visually inspect. Strange that the E-feed would not be back wired through a separate brkr, there by providing a more assured way of isolation from the POCO,and then properly identified as such.
Usually a transfer switch is fed from both the POCO and the generator. The switch selects one or the other, never both.

Why do you assume the T/S feeds to the LOAD side of the main brkr? The T/S selects power from either the POCO or the generator, never both. Normally, it would feed the LINE side of the main breaker.


You need to open the main panel and verify where the output from the T/S actually connects!!!
 

LarryFine

Master Electrician Electric Contractor Richmond VA
Location
Henrico County, VA
Occupation
Electrical Contractor
As the system stands now,/normal operation, If the T/S were to be thrown, 400a of main power would be present at the pins of the E-GEN plug.
That means the utility supply connected to the T/S's common terminals, selecting between feeding the panel or feeding the inlet. This is wrong!

The load, i.e., the panel, is supposed to be connected to the T/S's common terminals, selecting between the utility or the inlet feeding the panel.
 

ggunn

PE (Electrical), NABCEP certified
Location
Austin, TX, USA
Occupation
Electrical Engineer - Photovoltaic Systems
The T/S is wired into the main brkr panel......I assume to the LOAD side of the main brkr.
Why would you assume that? Normally the transfer switch is ahead (on the line side) of the MDP main breaker so either the grid or the generator, but not both, feeds the panel.
 

Todd0x1

Senior Member
Location
CA
A 100 amp pin receptacle (female) or Inlet (chassis mounted male)?

If throwing the transfer switch with nothing connected to the 100 amp pin shuts the power off or not would tell you quite a bit....
 
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