The Electrical Contractor Network

ECN Electrical Forum
Discussion Forums for Electricians, Inspectors and Related Professionals

Books, Tools and Test Equipment for Electrical and Construction Trades

Register Now!

Register Now!

We want your input!

Featured:
   

2017 NEC and Related
2017 NEC
Now Available!

   
Recent Posts
230 or 345 kV transmission lines?
by Vlado
Yesterday at 09:33 AM
breaker meltdown
by crselectric
Yesterday at 12:42 AM
Electrical mast flashing product
by ThomasWinfrey
09/22/16 12:14 AM
What estimating software do you recommend?
by sparky
09/21/16 07:20 PM
"Dry Run" Inspection goes awry
by HotLine1
09/20/16 07:39 PM
New in the Gallery:
12.5A through 0.75mm˛ flex (just out of curiosity)
Shout Box

Top Posters (30 Days)
HotLine1 17
sparky 9
gfretwell 9
sparky66wv 8
Vlado 6
Who's Online
0 registered (), 254 Guests and 5 Spiders online.
Key: Admin, Global Mod, Mod
Topic Options
Rate This Topic
#168778 - 09/14/07 05:10 PM Optional Standby Generators / 702
Gmack Offline
Junior Member

Registered: 05/14/06
Posts: 30
Loc: Michigan
Hello everyone.

After installing a 16KW Generac genset for a customer of mine who is terminal / ill, I have some comments and questions for the forum.

The Generac is a quality "USA" { i hope] product and it came in a box way to ready to go. So easy to insatll. Full rated SE ATS "prewired".

It worked perfectly and was/ is running self exercises weekly and provides whole house standby power when needed on demand. Works like a charm.

Down side?

OEM support isnt there if you are not willing to stock parts for warranty etc, and spend a lot of money attending seminars and the like in their town in Wisconsin and visting "the factory".

I was contacted by them and I told them my opinion. They should bring field reps to our towns and provide info and training. Havent heard from them since.

So Im looking around for other options and wondered if the forum might have some from the memebers.

Now to ART 702. I insalled the 16KW with ATS on the whole house. I bypassed the entire 100 amp main and re-feed all loads from a 70 amp OEM prewired asslembly to the ATS rated
at 100 amp with all the 2-pole 50, 40, 30, 5 SP 15's, 5 SP 20's. Plenty of power on Standby.

But on normal power/utility the home is now fed from a 2P 70 until a outage occurs. Any opinions?

I and the AHJ talked it thru and he passed it as is.

Seems kind of gray if you get my meaning.

BTW, I tried to explain to the customer in lay terms why not to feed all loads but he prevailed and I knew that everything would hold up. No hazards. But I still was cautious about my AHJ.

I know/think that not all lacals would buy this install but the gear is listed as 100 amp SE fed from a normal/utility 70.

I know it comes to to load/demand but I think that the Nec and this particular "approved"/ listed OEM havent yet met.

Thanks in advance.

Top
Work Gear for Electricians and the Trades

Work Gear for Electricians and the Trades
Work Gear for Electricians and the Trades
Arc Flash Clothing, Gloves, KneePads, Tool Belts, Pouches, Tool Carriers, etc. etc....

#168781 - 09/14/07 05:59 PM Re: Optional Standby Generators / 702 [Re: Gmack]
Active 1 Offline
Member

Registered: 02/22/03
Posts: 684
Loc: Grayslake IL, USA
Maybe I don't understand your set-up.

Do you have a disconect and OCP on the service?

If it is one of those 16 circuit ATS that came prepackaged with the gen it was probibly wired internally and with the sealtite wip using #4 THWN.

They advertise them as a 100 A transfer switch that is pre-wired. Except, they are not pre-wired at 100 amps. They are wired for the size of the gen they came with.

If it was fed with natural gas it only has a 15KW rating (62.5 amps)

Quote:
"at 100 amp with all the 2-pole 50, 40, 30, 5 SP 15's, 5 SP 20's. Plenty of power on Standby."
More like plenty of CB on standby.


Also keep in mind Those units are not intended for, listed as, and warn against using for life support.

If you need support Generac will give you a local dealer phone number. Nothing better than getting those how do I install this generator I didn't buy from you questions. Except calls for warrenty work on units purchased elcewhere.

They do have traveling classes but it's at a cost to the student. It was too high IMO if I remember corectly.

Generac shifts almost the product support & burden on the installing dealers while the retail dealers (box and online) stores sell for not too much over your dealer cost.

Are you hoping it's a quality product or a USA product?

Top
#168783 - 09/14/07 06:05 PM Re: Optional Standby Generators / 702 [Re: Gmack]
renosteinke Offline
Cat Servant
Member

Registered: 01/22/05
Posts: 5299
Loc: Blue Collar Country
Generators. Probably both the simplest and most misunderstood part of the NEC. Let's look at some basics. (I know, this isn't really what the thread asks ... but I think it needs mentioning).

A generator ... or, for that matter, solar panels, wind turbines, UPS battery banks, and every other secondary power supply is essentially an alternative to the PoCo. Therefor, it fits into your system in the same way the PoCo does. This is why the transfer switch is so important: it is essential that things get fed by only one "PoCo" at a time.

So, your arrangement is PoCo (or Genny) > Transfer switch > main disconnect.
Yes, there ought to be a disconnect to remove each power supply from the transfer switch. I'm not sure what the name of these disconnects is, but "main" is clearly wrong. Disconnect the Utility power ... and all yuo succeed in doing is turning on the generator!

Then there is the matter of generator sizing, as well as generator exercising. The generator operates best under load. Most manufacturers recommend that the generator operate at 75%-90% of it's capacity.
What this means is that, to determine size, you put an amp clamp on the PoCo feed, and see what they are actually using. It matters not what the nominal 'service size' may be. A customer whose 400 amp service is only actually drawing 37 amps per leg gets the genny sized for the 37 amps.

Besides correct sizing, it is important that the generator operate regularly UNDER LOAD. There are two different ways to do this.

One method is to actually transfer the load, and have the generator power the place for a while. Usually, this is a perfectly good way to do things.

Yet, when things are not so ideal ... for example, when the genny is way oversized (to allow for several unpredictable large loads operating at the same time, or when an application falls between nominal sizes), then a load bank is used. A 'load bank' is a multi-stage giant toaster, with resistance coils that impose an artificial load while the genny runs.


Since the run from the genny to the transfer switch is analogous to the PoCo, some of their practices (NESC) are relevant.
For example, the 'breaker' on the genny is there to protect the genny - not the wires. Your wiring ought to be kept separate from the 'load' wiring, just as your service wiring is kept separate.

Our friends at Generac seem to be repeating their moderately successful approach from 15 years ago: using VERY aggressive, high pressure sales methods and flooding the press with ads to pump up sales ... mainly to folks who don't know, need, or use generators. Their product, and their sales agreement, seem entirely based upon making you captive to their marketing department.

Suffice it to observe that I have yet to install a Generac; engineers seem to prefer to specify other makes.

Top
#168784 - 09/14/07 06:09 PM Re: Optional Standby Generators / 702 [Re: Gmack]
frenchelectrican Offline

Member

Registered: 02/06/03
Posts: 938
Loc: Wi/ Paris France { France for ...
 Originally Posted By: Gmack
Hello everyone.

After installing a 16KW Generac genset for a customer of mine who is terminal / ill, I have some comments and questions for the forum.

The Generac is a quality "USA" { i hope] product and it came in a box way to ready to go. So easy to insatll. Full rated SE ATS "prewired".

It worked perfectly and was/ is running self exercises weekly and provides whole house standby power when needed on demand. Works like a charm.

Down side?

OEM support isnt there if you are not willing to stock parts for warranty etc, and spend a lot of money attending seminars and the like in their town in Wisconsin and visting "the factory".



that about it with the Generarc unit they are kinda pain in the butt with warranty related issues belive me i have fair share with them allready and the prewired transfer switching device that part i am not too keen with it IMO kinda like light duty to me

you did mention about life support that will get very sticky issue will crop up as long you have somekind of back up battery power to run the lifesupport until the generator kicked in how fast i dont know because each area is diffrent they can be anywhere from 10 sec to several minuites depending on the set up.

i will let other chime in with their experance also i know few members were not too thrilled with this either i allready talk to them in the chat room.

Merci, Marc
_________________________
Pas de problme,il marche n'est-ce pas?"(No problem, it works doesn't it?)


Top
#168794 - 09/15/07 07:12 AM Re: Optional Standby Generators / 702 [Re: frenchelectrican]
Gmack Offline
Junior Member

Registered: 05/14/06
Posts: 30
Loc: Michigan
Thank you all for responding.

I will expand on my OP and comment collectively.

The service is a standard 100 amp with a 16 circuit CH MB panel. I installed the 16 circuit ATS adjacent and wire nutted all loads off the CH/MB service panel over to the ATS/load center.

I plugged a 2P 70 CH CB on/in the service panel and fed the utility line side of the ATS/load center combo pre-wired from Generac and listed for SE. All this was spec'd in the info package provided in the box.

The feed whip was # 6 not #4 provided pre-wired. The genset has a 65 amp MB/Disconnect under the lid.

Someone mentioned to size according to a clamped actual load but the equipment/ATS does that for you. In this case I needed "16 circuits" to reboot the loads. Single and 2 pole. Generac couples this with a 16 KW / 16 circuit set up.
All listed.

We could try "load shedding" and or a smaller genset with fewer circuits, that was my orginal intent, but as I stated this customer had to have his entire home on line, 24/7.

But, the home stil has a 100 amp service, which is code compliant, maybe except that the house is now fed from a 2P 70. But again it is backed up from the 100 amp MB.

The AJH and I agreed that the install "worked".

Remember this is a "optional" standby, not required, so life support/saftey would not have to be met as in 700/701.

My contention is that as long as the 100 amp service is original and code compliant, the rest is ok too.

But the electrician side of me feels that there is a code "issue" in this mix.

Some mentioned that shutting off the main would just start the genset. That is true. Bad situation when and if the fire department yanks the meter only to start the genset not realizing it or fumbling around not knowing how to disconnect it. Lifting the lid. Or recognizing a viewable disconnect.

There are many issues here that the NEC, EC's and AJH's are going to have to sort out.

Finally, someone asked if I wanted USA or quality. My answer, both. Im looking for another product line because of the fore mentioned Generac issues. But I must still say that the product is very good and the day I walked into HD I got a whopping 20% off which translated to $500.00. Way better than anything online could match.

And they dropped that 400# unit on the jobsite curb for a paltry $59.00.

All in all it was a "good" job. Except for Generac customer service.




Edited by Gmack (09/15/07 07:16 AM)

Top
#168807 - 09/15/07 01:40 PM Re: Optional Standby Generators / 702 [Re: Gmack]
Active 1 Offline
Member

Registered: 02/22/03
Posts: 684
Loc: Grayslake IL, USA
The problem with buying online or Home Depot is they will not do anything for you when there is a problem with a unit.
You will get a run around until you get a local installer dealer that may not be concerned with your customer and warrenty issue.

On top of that HD also sells instalation of these units thru 3rd parties maybe working for too little. Remember they are your compitition who's goal is to take over your market of the more profitable jobs.

The units are made in WI. Liquid cooled have someone eleces engine. Off the top of my head I would say more than 50% have some sort of problem or failure in the first 2 years. Normally minnor but when it don't work in a power failure after all that money customers want blood.

Manufactures warrenty aside your state laws might say you the seller/installer are responcable for the gen working corectly for a period of time such as an implied warrenty. Meaning you sold them something and it should work. Go back to HD and you will get an 800 # run around.

Also keep in mind who is responcable if the unit fails and there is damage such as a flooded basement.

Quote:
"Someone mentioned to size according to a clamped actual load but the equipment/ATS does that for you. In this case I needed "16 circuits" to reboot the loads. Single and 2 pole. Generac couples this with a 16 KW / 16 circuit set up.
All listed."

They were talking about sizing the gen and or the load on it for your situation. Gererac does not do that for you.
Just because they sold you a 16 space ATS with a unit does not mean it is sized for anything except to to fit in the shipping box.

See 220-10 Computed load of a feeder or service shall not be less than the sum of the loads on the branch circuits.

I don't know the loads and size of the home. Running it with #6 sounds a bit weak just as a personal opinion. With a bit more work the ATS could have been fed with a 100A circuit.

Quote:
"Some mentioned that shutting off the main would just start the genset. That is true. Bad situation when and if the fire department yanks the meter only to start the genset not realizing it or fumbling around not knowing how to disconnect it. Lifting the lid. Or recognizing a viewable disconnect."

See 702-8 Signs
There is no other disconect on these units except locked under the hood unless you added one. My guess is firefighters would turn off fuel supplys also if they want to disconect power. I believe I read here some fire departments have a policy not to pull the electric meter because of past cases of injuries doing it.

Top
#168809 - 09/15/07 03:46 PM Re: Optional Standby Generators / 702 [Re: Active 1]
Gmack Offline
Junior Member

Registered: 05/14/06
Posts: 30
Loc: Michigan
Active 1, thank you for your reply.

I agree with you, on most of it.

But I did my part in sizing and Generac did theirs too. I calculated the load at full load with more to spare, [on demand] and then some.

Why? thats my job.

Generac spec'd this unit to start 3 AC units and a boat load of other "lite" loads.

As one electrician to another. More was in the box than cubic feet.

Its NEC issues here.

Keep in mind, we EC's we buy 59 cent devices at the same HD that are listed/lawyer proof, we hope.

I explained why I needed 16 circuit/ 16/15 KW genset listed for./as SE.

If you would like to re- engineer my project here as described then please do so.

How would you do it?

Thats the point of my OP. Keep the NEC and the AHJ in mind in your reply if you would.

But first have a cold one . Then come back later.

Top
#168915 - 09/20/07 04:15 AM Re: Optional Standby Generators / 702 [Re: Gmack]
SteveFehr Offline
Member

Registered: 03/19/05
Posts: 1192
Loc: Chesapeake, VA
If I was doing it, I'd put in redundant paralleling generators feeding a PLC-controlled switchboard that automatically load-sheds less critical circuits when panel load (utility or generator) approaches capacity, with all receptacle circuits fed from UPS.

Honestly, I don't think this guy needs that, though. So long as your calcs show his load will never exceed 67A (EG, the automatic generator can support any and all loads demanded of it) your setup sounds fine for a house, and perfectly legal, and perfectly safe. NOW, when the next family moves in and really likes coffee and has 3 computers and a big-screen TV and puts in a couple more window AC units, etc, and those calcs are shot to hell, then you may be revisiting this home to move some of those circuits back to the non-generator panel...

Top
#168927 - 09/20/07 01:02 PM Re: Optional Standby Generators / 702 [Re: SteveFehr]
Gmack Offline
Junior Member

Registered: 05/14/06
Posts: 30
Loc: Michigan
SteveFehr

What we now have in this particular install is a 100 amp MB 16 circuit CH "service panel" feeding the whole house, as you mentioned, thru the 16 circuit ATS.

That CH service panel has a 14 "future" circuit capacity already to go.

There are issues though. Gutter space in that CH with all those wire nuts and crowding of "house" wires and cross over ATS load wires.

If I were to go back in the condtions that you described, I would upgrade the home to a 200amp, maybe add some auxilary gutter, {terminal strips would be a nice touch] and wire all future/new loads to the 200 amp service and leave the genset as is.

But you are correct, I could have a whole new animal by way of standby load preference from a new customer.

But in a house of this type and property size. No additiions are possible. It has central air already, etc.

I gave this customer as much product as he could afford/willing to pay and achieved his goal of whole house standby power.

.

Top



ECN Electrical Forums - sponsored by Electrical Contractor Network - Electrical and Code Related Discussion for Electrical Contractors, Electricians, Inspectors, Instructors, Engineers and other related Professionals