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Old 03-16-2010, 10:58 AM   #16
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Quote:
Originally Posted by Scuba_Dave View Post
NEC 700.5 does indicate the emergency system must have capacity for all loads to be served at the same time

I can't find anything (yet) that states it must be able to serve all possible loads
served at the time, to me, would be interpreted as all connected loads whether they are actually being used at the time or not. So, if, basically, if you used just the transfer switch, your generator would have to be able to supply basically all loads powered by the panel just as the POCO system would.

I think (but definitely not sure) that this would mean a sub-panel system would have to be utilized. Even the interlock system, although it does have a breaker limiting the power available, does not actually limit the loads connected. It only limits the power available. While that would prevent the genset from being overloaded, it does not comply with the requirement of

"must have capacity for all loads to be served at the same time"

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Old 03-16-2010, 11:01 AM   #17
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Quote:
Originally Posted by nap View Post
served at the time, to me, would be interpreted as all connected loads whether they are actually being used at the time or not. So, if, basically, if you used just the transfer switch, your generator would have to be able to supply basically all loads powered by the panel just as the POCO system would.

I think (but definitely not sure) that this would mean a sub-panel system would have to be utilized. Even the interlock system, although it does have a breaker limiting the power available, does not actually limit the loads connected. It only limits the power available. While that would prevent the genset from being overloaded, it does not comply with the requirement of

"must have capacity for all loads to be served at the same time"

STUBBIE!!!!!
It also refers to permanently installed systems. A portable generator is not a permanently innstalled system. Article 702.
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Old 03-16-2010, 11:01 AM   #18
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I looked over the http://www.interlockkit.com/ web site. It includes the instructions to turn off all breakers before turning on the generator breaker, then turn on only the required breakers that prevent you from overloading your generator. So with the interlock, there isn't anything that will prevent the user from overloading the generator.
Exactly. I use one here at home.

Quote:
Originally Posted by Scuba_Dave View Post
NEC 700.5 does indicate the emergency system must have capacity for all loads to be served at the same time

I can't find anything (yet) that states it must be able to serve all possible loads
Good point Dave. I think if you keep reading article 700.5 (B) we can use partial points of service. IMO a WH would be an emergency system....LOL. After all, an ATS does not supply the complete dwelling or structure in every case.
I am glad you mentioned this. I am going to check into it further. Thanks
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Old 03-16-2010, 11:05 AM   #19
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Section 702.5(1) seems to apply to this type of situation:

"Where manual transfer equipment is used, an optional standby system shall have adequate capacity and rating for the supply of all equipment intended to be operated at on time. The user of the optional standby system shall be permitted to select the load connected to the system."

From my point of view, that seems to pretty much say you can use on of these panel interlock kits... just don't overload your generator (duh).
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Old 03-16-2010, 11:14 AM   #20
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I have a 50a hot tub, 50a 2nd stove, 20a 240v pool pump + other loads that I would not consider running in an emergency

My whole house load calc is 143a
I can't see being required to provide power for all possible loads

My emergency loads would be HEAT 1st
Microwave or a hot plate for cooking, some lights
WH if power is out going on 2 days & no expected restoration of POCO power

With wood heat, LOTS of candles & oil lamps I have very little I need as far as power goes in an emergency
The most recent outage was maybe 2-4 hours ?
I never even started the Gen



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Old 03-16-2010, 11:15 AM   #21
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ok, now you are going to make me start reading.


article 700 does not apply to a temp backup system as an "emergency system" is defined as a legally required and are automatic (second paragraph of 700.1)

701 doesn't apply as it deals with legally required standby systems

702 seems to apply

so 702.5(B)(1) Manual transfer equipment

where manual transfer equipment is used, an optional standby system shall have adequate capacity and rating for the supply of ALL equipment to be operated at one time. The user of the optional standby system shall be permitted to select the load connected to the system.

so, ignore my question before. Based on that, whomever shall control the manual system shall be able to turn off breakers to limit the possible load.


dave, you got me in trouble again!!!
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Old 03-16-2010, 11:32 AM   #22
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Hey....I did say "yet" !! I needed to read more....Thanks
I'm wet vac'ing the basement (wet indoor/outdoor rug), checking the sump pump, getting trash ready & trying to get the trim up so I can side the house



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Old 03-16-2010, 02:08 PM   #23
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Thanks for all the great info guys;
It makes sense that the user should be allowed to manually select the branches that will remain on when the genny is running. I can understand the different code for automatic and/or required emergency systems.

What I would do, is match the breaker for the generator input to be not higher than the max rating of the genny. That way, if someone switches on more load than it can handle, the breaker trips, and protects the genny.

I could also install a sub panel, and put the transfer switch between it and the main panel, feeding the genny power into the other side of the transfer switch. Then, in the sub panel, use a breaker of appropriate size as the main breaker to protect the genny.
This way, I wouldn't have to worry about what is on and what is not when the genny is started and the transfer switch thrown over.

Still; I like the simple method of using the mechanical interlock. I would assume that I could get one for my CH panel, and installation wouldn't require a rocket scientist<g>.

At this point, I'm not sure I am going to buy the generator; my dad has expressed some concern over the issue, since we just escaped this nor'easter. We didn't lose POCO at all during this storm; but the way I see it, the generator is an insurance policy. We have at least $300 worth of food in the freezer most of the time, and my dad was very upset when we lost power for about 8 hours one summer night in 2007.
It's only a matter of time until we have another major outage.

While we can just buy a portable generator and use heavy extension cords to run power to critical appliances, I don't like this method. What happens if the power fails during a winter blizzard? Then how do we fire up our gas furnace without power? I would have to pull the wires off of the breaker, or a junction box to the furnace, and attach a plug to connect it. Same goes for our gas oven. It won't work without electrical power.

For the extra cost of doing it right, the benefit is significant.

I'm going to download this entire thread and keep it for reference, so when I need to do this job, I will be able to retrieve this great advice.

Thanks all

FW
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Old 03-16-2010, 02:12 PM   #24
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Quote:
Originally Posted by Scuba_Dave View Post
NEC 700.5 does indicate the emergency system must have capacity for all loads to be served at the same time

I can't find anything (yet) that states it must be able to serve all possible loads
Scuba_Dave; I love your avatar! Is that you in your early years of playing with electricity?

FW
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Old 03-16-2010, 03:46 PM   #25
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Quote:
Originally Posted by KE2KB View Post
Thanks for all the great info guys;
It makes sense that the user should be allowed to manually select the branches that will remain on when the genny is running. I can understand the different code for automatic and/or required emergency systems.

What I would do, is match the breaker for the generator input to be not higher than the max rating of the genny. That way, if someone switches on more load than it can handle, the breaker trips, and protects the genny.

I could also install a sub panel, and put the transfer switch between it and the main panel, feeding the genny power into the other side of the transfer switch. Then, in the sub panel, use a breaker of appropriate size as the main breaker to protect the genny.
This way, I wouldn't have to worry about what is on and what is not when the genny is started and the transfer switch thrown over.

Still; I like the simple method of using the mechanical interlock. I would assume that I could get one for my CH panel, and installation wouldn't require a rocket scientist<g>.

At this point, I'm not sure I am going to buy the generator; my dad has expressed some concern over the issue, since we just escaped this nor'easter. We didn't lose POCO at all during this storm; but the way I see it, the generator is an insurance policy. We have at least $300 worth of food in the freezer most of the time, and my dad was very upset when we lost power for about 8 hours one summer night in 2007.
It's only a matter of time until we have another major outage.

While we can just buy a portable generator and use heavy extension cords to run power to critical appliances, I don't like this method. What happens if the power fails during a winter blizzard? Then how do we fire up our gas furnace without power? I would have to pull the wires off of the breaker, or a junction box to the furnace, and attach a plug to connect it. Same goes for our gas oven. It won't work without electrical power.

For the extra cost of doing it right, the benefit is significant.

I'm going to download this entire thread and keep it for reference, so when I need to do this job, I will be able to retrieve this great advice.

Thanks all

FW
If you do go the route of the interlock don't buy from interlockkit.com they are a ripoff, i am not sure about cutler-hammer but square-d and siemens make interlock kits for their boxes that are much more pleasing on the eyes and about 50% less, I paid $65.00 for my interlock vs. 150.00 from that website.
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Old 03-16-2010, 08:02 PM   #26
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I installed the SquareD kit:
http://static.schneider-electric.us/...273-809-02.pdf

In a related development, I recently got the PowerBack unit from Reliance. It lets you know when power comes back.
http://www.nooutage.com/pdf/RelianceControls_THP108.pdf
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Old 03-16-2010, 08:15 PM   #27
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$150 for a piece of metal with a few bends & slots cut out

I guess not a DIY thing



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Old 03-16-2010, 09:04 PM   #28
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$150 for a piece of metal with a few bends & slots cut out

I guess not a DIY thing

$150 for a UL Listing
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Old 03-16-2010, 09:31 PM   #29
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Quote:
Originally Posted by Scuba_Dave View Post
$150 for a piece of metal with a few bends & slots cut out

I guess not a DIY thing
$250 if you have them custom make one that is not from their inventory. Their product is very well made and after having had a machine shop make some for me out of aluminum stock because interlock.com didn't have what I needed .... I'm here to tell you there is more to it than meets the eye. So the price is not out of line. Factory interlocks are a better way to go but for panels that don't have factory interlocks I wouldn't be afraid of interlock.com. just stay away from having them take your measurements and custom building one. If you talk to Justin at interlock.com you will find out why.

Interlocks are not my first choice nor are portable generators but they get the job done and done safely along with economically. All power companies I've worked with will accept interlocks. You have to get approval or phone them for the list of approved devices in many jurisdictions. There was a slight problem with having them made by my machine shop so I no longer custom make interlocks for a panel that doesn't have a factory interlock or listed interlock available. I would put mine against any out there however but it's all about liabilty ... so I advise against it.
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Old 03-17-2010, 08:37 AM   #30
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Originally Posted by naehring2000 View Post
If you do go the route of the interlock don't buy from interlockkit.com they are a ripoff, i am not sure about cutler-hammer but square-d and siemens make interlock kits for their boxes that are much more pleasing on the eyes and about 50% less, I paid $65.00 for my interlock vs. 150.00 from that website.
Thanks for that info. I think the panel shown in the picture was a CH.

FW
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