Wrenches,
Recently, we took delivery of a 40 kW LPG generator made by Gillette.
Inspecting the factory wiring of the unit, I had some concerns which are
outlined in detail below, with an engineer's response inline. The concerns are
using #4 wire to pull 175A; no plastic bushings on metallic conduit, and ground
lugs on top of painted surfaces / and insufficiently torqued.
The engineer response has left me somewhat baffled / frustrated in that I do
not feel that actual issues have been addressed. I don't really care what UL or
any other authority tells me - pulling 175A continually for many hrs through a
#4 wire I think is asking for trouble. And my customer won't really care about
what the UL ratings say if they are dealing with a melted alternator.
Am I missing something here?
Kevin
RE: SP-410-1-1LO S/N:
I am responding to the concerns written below both in the capacity as designer
and as U.L. liaison.
We have received this generator, mostly intact. Some freight damage to the
battery support cross member due to forks not extending the full depth of the
crate, and are working with the freight company to resolve that.
Sorry for the experienced freight damage.
However, there are some SERIOUS and DANGEROUS issues pertaining to the wiring
of the alternator! It is obvious that wiring was not done by an electrician.
There are no serious or dangerous issues on this (built to U.L. recognized
spec) Gillette Generator as referred to in this writing. And - you are correct-
this wiring, as 'factory wiring and not 'field' wiring, does not require or use
the specific qualifications of a licensed electrician. The well
trained/supervised workers here at Gillette have many years of experience
building the product and are guided as need by a competent engineering staff.
Specifically:
- Alternator to circuit breaker wiring was done with #4 wire (rated 60A max).
Per your own load chart inside the breaker enclosure (photo attached), that
wire should be 4/0 to carry the 175A that this generator is capable of
producing.
This observation is incorrect. The load wiring sizing schedule affixed to the
side of the circuit breaker box is for 'field connectivity' at 75 deg. F. We do
our 'factory wiring ' on a different schedule using load cabling from the
generator to the top of the circuit breaker rated at 150 deg. F. All of this
cabling has been done, tested and proven by U.L
- There were no plastic bushings (see photo) where the wires exit the metal
conduit.
The conduit bushing involved is the correct U.L. approved component for the
installation of spiral wound metal conduit required to be installed on 'open'
style generator assemblies. A plastic bushing is NOT required as this is again
'factory wiring', not 'field wiring.
- What would have happened here is the wire heats up due to gross under sizing,
melts the insulation, and shorts it out. Resulting in a fire or destruction of
the brand new alternator, and the associated legal proceedings involving all
parties and a general nightmare for all of us.
disagree, on several fronts. Referencing the specification standard U.L. 2200,
many times- local inspectors blur the line between its dominance for standby
generator systems and NEC-70 (NEC- code). The former covers 'factory' design
wiring on stationary standby generators subject to witness testing by a U.L.
certified representative. The latter applies to 'field wiring'- that is
anything outside the box including connection conduits, load wiring ( at 75
deg. F) transfer switches, distribution panes and the like. As resident
designer for the past twenty-six years, I have myself- written eight
standards/code rebuttals successfully, both for U.L. and local inspectors.
Comparing a 4ga, 2ga, 1ga and the like against a different class of wiring such
as a 4/0 would certainly be cause for alarm. But, clearly here the alarm is
unwarranted.
- the ground lug on the alternator was not fastened properly (a
short stud with a nut on it - no way to get proper torque on it - should be a
bolt), and both this lug and the lug inside the breaker enclosure was fitted on
top of a painted surface. Every electrician knows you need to scrape off the
paint so as to allow for proper conductivity.
This lug is not supplied by us. It is supplied as part of the generator
construction built by Marathon. Marathon generators are certified for U.L.
1004B- generator assemblies and U.L. 1446 for insulation. This is the equipment
issued as part of that U.L. certified design. as to their design vs. a 'bolt'
going into the threads of the hole- if it was really an issue, it would not
have passed their U.L. certification testing. Their generator assemblies bear
their U.L. file certification under R/C (JZGZ2) and listing (JZGZ). In regards
to the paint removal, the engine and generator are cable grounded to the frame
of the generator assembly and serrated hardware is used during assembly to
scratch into the painted surfaces of the boxes and frame. As you notice in the
picture- the threads in the generator housing sleeve- are not painted.
These are issues that we are able to remedy. But my client,
being very hands on has noticed this and inquired, quite reasonably, as to why
they are paying Energy Alternatives to repair something that they paid for and
should have been delivered properly done in the first place?
To my findings, there is no warrantable work required.
I think the fairest solution to this is for us to remedy these
defects and to have Collicutt reimburse use for time and materials. I will
complete the work and send you the total bill for compensation unless you would
like to approach this in a different method. We are hoping to go live with this
unit in the next few days once the gas fitting is completed.
As stated above- Not required.
I hope these responses help clarify the items in question.
Regards,
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