Cost of Emergency Generator Hookups

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Old 01-20-10, 04:37 PM
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Cost of Emergency Generator Hookups

Hey everyone. I am new to the forum so let me know if these questions don't belong here.

I bought a portable generator that has an output of 8,000 watts. It has a plug on it to hook up a 240v/30 amp plug. I bought it to use around the farm, but I would also like to use it in emergencies to power parts of my house, like the well pump and microwave. So I have a couple of questions:

1) Will 30 amps at 240v translate to 60 amps of available current at 120v?

2) I have two panels in my house, each with a 200 amp main breaker. I want to put a 30amp double pole in each panel and split the generator power across each panel. Is that okay to do?

3) I got quoted $1,300.00 to hook up to the electrical for this application. The work involves the following:

- Put a 30 amp/240v plug outside the house with a portable cord to the generator
- Add a 30 amp double pole breaker to each panel
- Add a mechanical interlock to each panel at the main breaker.

Is that a reasonable price for this work?

Thanks so much for your help
 
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Old 01-20-10, 06:20 PM
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Originally Posted by fins2thright View Post
1) Will 30 amps at 240v translate to 60 amps of available current at 120v?
Essentially yes, but the load needs to be balanced across the generator legs to get the full 60A at 120V.

2) I have two panels in my house, each with a 200 amp main breaker. I want to put a 30amp double pole in each panel and split the generator power across each panel. Is that okay to do?
As long as the panels have an interlock installed.

Is that a reasonable price for this work?
What kind of panels are they? What are the approximate distances between the panels, generators? What's the access like -- open studs, finished walls, masonry, etc?

Are the loads you need to power spread across both panels? Does it make sense to install a dedicated transfer panel that powers all of the emergency loads?
 
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Old 01-20-10, 06:47 PM
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8k ain't a lot of wattage to split between two panels. In our area certain electrical and HVAC houses are advertising a 30k ( I believe) propane, hard set, hooked up to a Generac for less than $3500. They autostart after 20 seconds of dead wire, self test once a week to charge the battery and self diagnose. That's the route I will take if this Kubota ever will die.
 
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Old 01-20-10, 08:04 PM
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Chandler .,

8Kw is not much but if the OP did have manual transfer switch then it is not a issue but if have automatic transfer switch and with NEC 08 code cycle they will have to sized to match the main breaker .,,

I know .,, I know I heard someone say EKK or cuss a word but a prime example if you have 200 amp automatic transfer switch you will need 48 Kw generator IMO that is seriously overkill for this useage { I heard some talking going on to change the code but not confirmed yet }


fins2thright.,

I am pretty much the same page as Ibpooks with the set up.

Merci,Marc
 
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Old 01-23-10, 06:45 AM
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For what is being done, that sounds very high. Especially given the fact that they intend to use a backfeed breaker setup rather than a dedicated manual transfer switch. With only an 8kW generator, you have potential to do serious damage that way, especially given the fact that you have 2 panels. and the loads may not be split evenly.

Your setup should be done with something like this
.

You pick which circuits you want to be powered off the gen. That would be your well pump, sump pump, lights, refrigerator, a selection of outlets, and your furnace. Each one gets connected to this switch, and then back to the circuit breaker. You will want to balance the larger loads between the poles of the generator. So for example, you would want your furnace on A, and the well pump on G. Refrigerator on B, microwave on G. And so on. That way you don't overload one side of the generator and wind up with a smoldering pile of ash. The tied switches are for 240v circuits, but you can remove the tie if you don't have any you want to run off the gen. Even though you see the generator plug on the front of the transfer switch, it can be hard-wired to a power inlet box outside the house.

This is a much safer way to run your critical circuits off a portable gen. Another byproduct of using a 'selected circuit' setup like this is you'd have an indication of when the power came back on. With a 'backfeed breaker' setup, the main is cut while the generator is running. So when the power comes back, you have no indication of that. At least with selected circuits, you'd know the power was back when the rest of the lights come on.

I just installed one of these at my mom's house. Let me know if you have any questions on it.
 
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Old 01-23-10, 07:02 AM
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A big thanks to everyone who replied. I feel like I know much more about the pitfalls of this hookup now.

@ JerseyMatt - That panel you suggested looks like the ticket. What is that thing called exactly and can you give me a model number or anything to give to my electrician?

Thanks everyone again.
 
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Old 01-23-10, 07:23 AM
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Originally Posted by fins2thright View Post
A big thanks to everyone who replied. I feel like I know much more about the pitfalls of this hookup now.

@ JerseyMatt - That panel you suggested looks like the ticket. What is that thing called exactly and can you give me a model number or anything to give to my electrician?

Thanks everyone again.
It's a GenTran model 30310V, 10 circuit manual transfer switch. I picked it up at Home Depot for $230. Now, how far apart are these panels? If they are right next to each other, honestly you can probably install this yourself in an hour or two, and save yourself a thousand bucks. It is designed for the average person who has changed an outlet or installed a light fixture to be able to do it.

If the panels are in different areas of the house, you would have to run conduit between them. That is still something very doable yourself, but much more of a pain than surface mounting some Romex like the electrician was probably originally going to do.
 
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Old 01-23-10, 11:10 AM
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I have the exact switch, and it probably took a couple of hours to hook up. Very simple and safe. I know you plan on doing it right, and forgive us for emphasizing it too much, but a good friend on our local POCO was killed during the power outage during Hurricane Ivan. Some numbnut hooked a generator directly to his panel's incoming wires. Of course it backfed 120 volts multiplied by 100+ through the transformers. When he went to repair the wire, 13k hit him on backfeed. Just be careful.
 
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Old 01-23-10, 01:41 PM
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Originally Posted by french277V View Post
Chandler .,

8Kw is not much but if the OP did have manual transfer switch then it is not a issue but if have automatic transfer switch and with NEC 08 code cycle they will have to sized to match the main breaker .,,

I know .,, I know I heard someone say EKK or cuss a word but a prime example if you have 200 amp automatic transfer switch you will need 48 Kw generator IMO that is seriously overkill for this useage { I heard some talking going on to change the code but not confirmed yet }


fc
wow, the things you learn by listening to marc.

when you say the genset has to be matched to the main breaker, is that the main breaker to the building, the rating of the transfer switch, or the main breaker on the sub that is the only powered panel when the gen-set engages?
 
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Old 01-23-10, 03:03 PM
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I still disagree with this interpretation of Article 702.5.

Even though you may say some areas interpret it that way, is not the way the code reads and I'd be willing to challenge that interpretation.

702.5 (B) System Capacity The calculations of load on the stand by source shall be made in accordance with Article 220 or other approved method

702.5(B)(2) Automatic Transfer Equipment Where automatic transfer equipment is used, an optional stand by system shall comply with the (2)(a) or (2)(b).
(a) Full Load. The stand by source shall be capable of supplying the full load transferred by the automatic transfer equipment.
Then "b" goes into load management systems.

The way this reads is: a load calculation is performed and the generator is sized accordingly. If a load calculation is performed and it comes out to 200 amps then I would say an upgrade is needed.

Most houses have a 200 amp service and most newer homes of size have 400 amp services(mostly for space and not necessarily load). I doubt it's the intention of the code to mandate a 45 KW or 100 KW generator when automatic transfer equipment is used.

Just my 2 cents
 
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Old 01-23-10, 03:22 PM
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so, under your interpretation, wirenut, it would be based on the size of the panel being powered by the generator, yes?

I would think that be a reasonable interpretation. There would be no reason to size the genset to exceed the demands placed on it.
 
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Old 01-23-10, 03:31 PM
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Not really "my" interpretation but, "ours" and we aren't under 08 yet.

The size of the generator needs to be sized according to a load calculation, not the size of a main breaker.

My house has a 200 amp service however, my load calculation comes to about 68 amps due to the fact that my major appliances are gas. Under that interpretation I would still need a 45 KW generator to supply the "load" but it's not close to 200 amps. Which would enable me to use about a 16KW.

PS: That would be like saying a house with a 100 amp service needs a 25 KW generator and a house with a 200 amp service needs a 45 KW even though the "actual load" is the same on the system.
 

Last edited by wirenut1110; 01-23-10 at 03:36 PM. Reason: added ps
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Old 01-23-10, 03:37 PM
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Just get yourself one of these, or call your local PoCo, they may rent them (many in the northern US do).

Generlink Automatic Transfer Switch — 50 Amp, Model# MA24-N | Transfer Switches | Northern Tool + Equipment

Bought one after Ivan (from somewhere else), no fuss, no muss, just leave the breakers in your main panel off for what you don't want to power or that your generator can't handle (in my case, that's just the central heat/air).
 
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Old 01-23-10, 03:40 PM
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Under the 08 code and some people's interpretation of it, that transfer switch would be illegal because your supplying a so called 200 amp or more load with 50 amps.
 
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Old 01-23-10, 03:53 PM
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Originally Posted by wirenut1110 View Post
Not really "my" interpretation but, "ours" and we aren't under 08 yet.

.
so how would this be applied if the genset fed a subpanel but allowed the disconnect of the main service from the POCO. Would the load calc on only that sub-panel be applicable for sizing?

btw: it's 2010 so the 11 will be out shortly. Just a bit behind the times aren't you?

I get to chuckle about it. Being from Michigan, we are usually at least 1 code cycle behind (actually almost skipped one if I heard correctly to catch up one time). We just went to the 08 last month. That is like light speed for us.
 
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Old 01-23-10, 03:53 PM
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"The stand by source shall be capable of supplying the full load transferred by the automatic transfer equipment."

I read that as, if you install a 50a transfer switch, your generator should supply 50a. Install a 30a, it should be capable of 30a. Just makes sense really, why create more power than you can transfer.

But, what if the generator supplies 50a, and you have a 30a switch. The source is capable of supplying the full load, but you've wasted 20a that has no where to go, but it still meets the letter of the code.

Now, does this section apply to *permanent* installations, or temporary ones. Ones that use an easily removable cord to route power from the generator to the switch would not, IMO, qualify as permanent.
 
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Old 01-23-10, 04:01 PM
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btw: it's 2010 so the 11 will be out shortly. Just a bit behind the times aren't you?
Hopefully never and I hope 2011 code took out the stupid stuff of the 08 or when we do adopt it (probably this Nov) they will have amendments.
Would the load calc on only that sub-panel be applicable for sizing?
In my "our" interpretation yes, but on the others, it would have to be sized on the breaker feeding it.

Pendragon: This transfer switch is switching the power at the meter so it is supplying the entire service whether it be 200 or 400 amps but the max generator supply is only 50.

Also, the code just says automatic or manual switch so, it doesn't pertain to permanent or temporary
 
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Old 01-23-10, 05:48 PM
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Originally Posted by chandler View Post
... a good friend on our local POCO was killed during the power outage during Hurricane Ivan. Some numbnut hooked a generator directly to his panel's incoming wires. Of course it backfed 120 volts multiplied by 100+ through the transformers. When he went to repair the wire, 13k hit him on backfeed. Just be careful.
Chandler, do you have any link to this unfortunate accident? I ask because I have heard/read about these things happening numerous times and yet I have never been able to get any first-hand information. While I am among the first to come down hard on anyone that even thinks about connecting a gennie without an approved disconnect my opinion is that few, if any, home generators could operating if they were connected to the utility system.

I make this statement because as soon as the generator was connected to the utility line it would also be feeding any other customer between the generator and the point where the utility lines are broken. Such load would normally cause the generator's circuit breaker to trip almost immediately.

There IS, however, always the chance that a lineman had already done all the safety checks to ensure the wires he (she) is working on are dead and then the clown connects his gennie. Even though the gennie trips the circuit breaker almost instantaneously I can see a surge going through the system and killing the lineman. I just wonder how often it really happens.

To everyone reading this thread: NEVER connect a generator to your house system without the benefit of an APPROVED transfer switch, transfer panel or circuit breaker interlock and NEVER attempt to defeat the positive disconnection of the utility from your generator.
 
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Old 01-23-10, 07:03 PM
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furd,

depending on where they were on the line and where the line may have been downed, the load could be minimized a lot. If the guy was on the end of a branch with the break before the main trunk, there could be as little as just the one service on the line.


we have a story of a farmer doing the same thing. As it goes, the lineman was not injured due to the fact he checked for power and it was showing hot, on the wrong side of the break.

I have never read any support for our situation, merely anecdotal.
 
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Old 01-23-10, 10:45 PM
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Originally Posted by Pendragon View Post
Just get yourself one of these, or call your local PoCo, they may rent them (many in the northern US do).

Generlink Automatic Transfer Switch 50 Amp, Model# MA24-N | Transfer Switches | Northern Tool + Equipment

Bought one after Ivan (from somewhere else), no fuss, no muss, just leave the breakers in your main panel off for what you don't want to power or that your generator can't handle (in my case, that's just the central heat/air).

Pendragon.,

The link you provide us almost all the POCO in state of Wisconsin do not allow this meter socket transfer switch format at all due their strict policy they do not want to mess around with that type of transfer switch.


Wirenut I do agree with your statement and I have challanged more than once with resdentail usage however in commercal / industrail it is not a issue.

I am going to wait and see what they change on 2011 NEC cycle I hope they clear up that matter.

Merci,Marc
 
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Old 01-24-10, 03:39 AM
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Furd, I had an answer to your post, but it must have gotten lost in hyperspace. I don't have a link to this particular instance, due to our being in small town USA. I will try to get more info and pass it along to you. I feel as you and Nap do, the wires were down, little load at the time the dipstick hooked up his generator, and Donnie was already into the works when it hit him. To my knowledge they have not located the culprit who did it, but you gotta figure you can at least narrow down the grid. I'd like to know.
 
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Old 01-24-10, 01:08 PM
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I'm not saying it couldn't happen, and I'm not trying to make light of his demise, but if this guy did in fact get electrocuted from a backfeed, it was due to his own carelessness. He committed a mortal sin as far as linesmen go. "If it's not grounded, it's not dead" is the golden rule. Had he clamped off the line to ground before working on it, he would still be alive.
 
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Old 01-24-10, 01:33 PM
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Not wanting to start an argument on semantics, but he didn't hook up the generator, so "it was due to his own carelessness" doesn't wash in my book. Power was down for 50 miles around and impossible to energize for at least 2 or 3 days. It is difficult to ground a downed wire on the load side of the transformer. The line side was grounded, and as I understand it, they were in the process of moving the downed wire to splice in a new section to restore power. But thanks for your input.
 
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Old 01-24-10, 02:28 PM
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Originally Posted by chandler View Post
Not wanting to start an argument on semantics, but he didn't hook up the generator, so "it was due to his own carelessness" doesn't wash in my book. Power was down for 50 miles around and impossible to energize for at least 2 or 3 days. It is difficult to ground a downed wire on the load side of the transformer. The line side was grounded, and as I understand it, they were in the process of moving the downed wire to splice in a new section to restore power. But thanks for your input.
That right there is all the more reason to cover your 6. When the power is out for long stretches, people do stupid things. And it don't matter how difficult it is or how far out the possibility of energizing the area is. You find a way to ground it. My uncle has been a linesman for 20 years, and he's got me interested in the trade. I've heard stories. ANY linesman who is killed by electricity, could have prevented it by following his safety guidelines.

There are also other ways that power could backfeed when an entire grid is out. How about a home that has solar panels and a net metering setup? Net metering inverters are supposed to shut down upon grid power failure, so as to prevent a backfeed situation. But if the inverter malfunctions, it will still pump power into the grid. Residential solar can be upwards of 30kW. Far more than Joe Schmuck with his 5kW generator. I sure wouldn't want to be touching that without grounding it either.

But you're right, lets not fight.
 
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Old 01-24-10, 02:49 PM
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I put in a SquareD generator interlock kit for about $100.
http://static.schneider-electric.us/...273-809-02.pdf
 
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Old 01-24-10, 05:18 PM
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Originally Posted by JerseyMatt View Post
That right there is all the more reason to cover your 6. When the power is out for long stretches, people do stupid things. And it don't matter how difficult it is or how far out the possibility of energizing the area is. You find a way to ground it. My uncle has been a linesman for 20 years, and he's got me interested in the trade. I've heard stories. ANY linesman who is killed by electricity, could have prevented it by following his safety guidelines.

There are also other ways that power could backfeed when an entire grid is out. How about a home that has solar panels and a net metering setup? Net metering inverters are supposed to shut down upon grid power failure, so as to prevent a backfeed situation. But if the inverter malfunctions, it will still pump power into the grid. Residential solar can be upwards of 30kW. Far more than Joe Schmuck with his 5kW generator. I sure wouldn't want to be touching that without grounding it either.

But you're right, lets not fight.
I dealt with alot of Med/High voltage system in commercal / industrail situation and I am very famuair with the event when the POCO { power compaine } system go down .

As far for Solar system that use netmetering they have build in interlock system so if the POCO system fail for any reason it will automatically isolated or disconnect the unit one of the two.

Furd.,

I will send you a PM with link with POCO faitites so give me a bit of time so I can get correct doucment I have too many listing so bear with me.

Merci,Marc
 
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Old 01-26-10, 07:33 AM
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I'm not an electrician, but it seems to me that the bolded part in the statement...

(a) Full Load. The stand by source shall be capable of supplying the full load transferred by the automatic transfer equipment.

...could be interpreted as the genset must be capable of supplying the maximum load that would ever go thru the ATS in that particular setup, i.e., the results of a load calculation based on everything that can be powered up when the ATS switches to the genset.

For the interpretation to mean a 200A main breaker in the ATS requires a genset capable of supplying 200A, it seems like the code would say something like...

(a) Full Load. The stand by source shall be capable of supplying the full load capable of being transferred by the automatic transfer equipment.

If the code really means the latter, doesn't that mean that companies like Generac are selling products that do not meet code by offering "pre-packaged" solutions (genset and ATS) with gensets less than 20kW (all the way down to 8kW) and ATS's with 100A main breakers?
 
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