[RE-wrenches] Generator factory wiring issues
bob at midnitesolar.com
bob at midnitesolar.com
Wed May 25 19:23:22 PDT 2016
UL evaluates products on internal temperature rises while it is used
normally.
They also evaluate the products under abnormal use, in various ways.
It may or may not have a fan. If you look inside an inverter, you will
see the same type of
things.... Large external battery cables connecting to smaller internal
cables and/or
bus-bars and circuit board traces. All sorts of things that probably
are not allowed
with NEC.
I think I saw a temperature of 150 degrees F mentioned here. That's nothing
compared to the highest temperatures seen in certain parts of the products.
Some wire, like in some transformer classes can reach as high as 220
degrees C (428 F) !
boB
On 5/25/2016 11:39 AM, Kevin Pegg wrote:
>
> Hi Daniel,
>
> Appreciate your thoughts on this.
>
> - This wire is contained inside 2" flexible metallic conduit, approx.
> 3' long from the alternator to the external breaker. Some of it is in
> free air, but most is contained within the conduit.
>
> - the main breaker is a 100% rated 175A.
>
> - This is an industrial generator is rated for continual operation at
> full load, and my expectations is all the wiring in that unit is
> suited to that. Will the site actually draw that? It is entirely
> possible during heavy loads & concurrent battery charging that it
> could well be running at max load for hrs at a time.
>
> The plastic bushing is easy to remedy, as is the ground lug.
>
> The wire is where I am not sure what to do. Everything I am hearing
> tells me that the #4 wire is undersized. So there is a dilemma. If I
> replace the wires myself then I believe I have voided the UL
> certification. But think have made a safer engine for my client. At
> the end of the day, it will be me who the client is calling if there
> is an issue.
>
> Just for kicks I opened up a couple 25 kW gens and factory wiring was
> either # 2 or # 4 for this same purpose. Hmm.
>
> Kevin
>
> *From:*RE-wrenches [mailto:re-wrenches-bounces at lists.re-wrenches.org]
> *On Behalf Of *Daniel Young
> *Sent:* May-25-16 7:24 AM
> *To:* 'RE-wrenches' <re-wrenches at lists.re-wrenches.org>
> *Subject:* Re: [RE-wrenches] Generator factory wiring issues
>
> 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 Professional^TM : 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
> <mailto: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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