[RE-wrenches] Generator factory wiring issues

[Daniel Young]

Kevin,

 

Based on what the engineer said, I think you both make valid points.

 

On the 4AWG wire: 

 

Type Z wire (150 C insulation) is rated for 190A based on 2014NEC table
310.15(B)(19). It's rated for 120A when in conduit. So is this wire where
you might call it in conduit or free air? I imagine the inside of a
generator enclosure is somewhere in the middle. Also I assume this is Z type
or similar based on the response stating 150 F (I know he meant C) wiring is
used.

 

Is this on a 175A breaker? If so then it should only pull 140A continuous
(maybe it's a 100% rated breaker?). And that really would not be great for a
generator. Usually we only design for a maximum of 80% loading on a
generator depending on elevation and a few other de-rate factors. In reality
do you expect more than 120A to be a true "continuous" load on this unit. I
don't know the answer, just worth thinking about.

 

Plastic bushings:

 

I sure would want them in a vibrating machine like a generator, but if UL
does not force them to, don't expect them to include it. (Capitalism at
work). You might be able to use an electricians trick where you cut a PVC
bushing and slip it over the existing wire, then you can thread it in the
end of the fitting and it is 95% as good as a normally installed bushing.. I
would not do it on a new install, but it's a useful trick when you walk up
on existing mistakes.

 

Lug:

 

You could continuity test it to see if it's a good connection, otherwise
that strikes me as no good either. Just another cost saving step for the
manu at the clients expense in my opinion. It'll work fine for now, but not
likely in 5-10yrs as corrosion sets in. I'd just throw a star washer
underneath if possible, but it sounds like the stud is not long enough.

 

So there is a little bitta' code and a lotta' opinion.

 

With Regards,

 

Daniel Young, 

NABCEP Certified PV Installation ProfessionalTM: Cert #031508-90

 

From: RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org] On
Behalf Of Kevin Pegg
Sent: Tuesday, May 24, 2016 6:14 PM
To: RE-wrenches <re-wrenches at lists.re-wrenches.org>
Subject: [RE-wrenches] Generator factory wiring issues

 

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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