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Link Posted: 9/2/2015 6:54:03 PM EDT
[#1]

ps
just a reminder:

when the cover is off the service panel...

and the main is ON:
- lethal voltage is present at the lugs at the top of the main breaker.
- every one of those metallic "tabs" on the service panel backplane has lethal voltage present.
- introduction of metallic objects (such as screwdrivers or wrenches) to the same areas will have undesirable results.  

and the main is OFF:
- lethal voltage is present at the lugs at the top of the main breaker.

ar-jedi

Link Posted: 9/2/2015 9:42:02 PM EDT
[#2]
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Quoted:
When we lose power, I use a heavy gage extension cord to power the refrigerator directly.  Nothing else is in critical need of power.  I do not power my whole house because it does not have an interlock.

Not only could back feeding hurt a lineman working to restore service,

if power comes on your generator will be killed and

two neighbors, each back feeding, will kill each other's generators.
View Quote


If you flip the main breaker, is that possible?
Link Posted: 9/2/2015 9:46:14 PM EDT
[#3]
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Quoted:


yes, that is one small, minor difference between the two approaches.

the other small, minor difference is that when you pull out the generator backfeed plug while the generator is running, there is lethal voltage present on the exposed copper blades.

ar-jedi


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Quoted:
Quoted:
Quoted:
When we lose power, I use a heavy gage extension cord to power the refrigerator directly.  Nothing else is in critical need of power.  I do not power my whole house because it does not have an interlock.

Not only could back feeding hurt a lineman working to restore service,

if power comes on your generator will be killed and

two neighbors, each back feeding, will kill each other's generators.



That won't happen if you shut off your main.  

I am totally against back feeding but if you do it right it really isn't much different than an interlock. The interlock merely makes it so that you can't screw up and leave the main on while the generator is actively feeding the panel.


yes, that is one small, minor difference between the two approaches.

the other small, minor difference is that when you pull out the generator backfeed plug while the generator is running, there is lethal voltage present on the exposed copper blades.

ar-jedi




so kill the genny breaker, then the genny, good no?
Link Posted: 9/2/2015 9:53:53 PM EDT
[#4]
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Quoted:
so kill the genny first
View Quote


gee, why didn't that occur to anyone before?

ar-jedi
Link Posted: 9/2/2015 10:38:26 PM EDT
[#5]
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Quoted:


gee, why didn't that occur to anyone before?

ar-jedi
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Quoted:
Quoted:
so kill the genny first


gee, why didn't that occur to anyone before?

ar-jedi


Right up till your 8 year old pulls the cord.
Link Posted: 9/3/2015 3:15:40 PM EDT
[#6]
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Quoted:


Right up till your 8 year old pulls the cord.
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so kill the genny first


gee, why didn't that occur to anyone before?

ar-jedi


Right up till your 8 year old pulls the cord.

Clearly if your 8 years old pulls the cord out of the wall and electrocutes himself it's his fault for not listening better when you told him not to do that. You need to better educate your child and wife on the "proper" way to connect and disconnect your generator. It's simple people, all you have to do is make sure the main is off and turn the generator breaker off before pulling the cord. People can't possibly ever screw that up...


FWIW, the above post is all sarcasm... despite the fact that I recognize that "suicide cords" are not dangerous when used properly and everything goes well, I also realize that things aren't always used safe and don't always goes perfectly. Really the cost to have an interlock put on your panel IS NOT WORTH THE HAZARDS OF USING A SUICIDE CORD... I'm stunned that people will sink hundreds of dollars into a generator, thousands into a big screen TV, tens of thousands into an A/C system, and yet they won't put $50 into connecting the generator properly/safely to run those items in a power outage...
Link Posted: 9/3/2015 9:20:20 PM EDT
[#7]
my problem with the interlock is panel space.  Installing a breaker just for the generator at the position close to the main breaker is not an option.  I have no kids.  My wife is only half retarded.  Although the interlock kit is a good idea, it is prohibitive for me.
Link Posted: 9/3/2015 10:13:17 PM EDT
[#8]
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Quoted:
my problem with the interlock is panel space.  Installing a breaker just for the generator at the position close to the main breaker is not an option.  I have no kids.  My wife is only half retarded.  Although the interlock kit is a good idea, it is prohibitive for me.
View Quote


perhaps an external transfer switch then?

obtain switch, mount near panel, play with wire nuts for an hour, success.

upsides: same isolation of generator power and POCO power as interlock.  simple to use.
downsides: initial cost, and limitation on the number of circuits you can power from the generator.  

ps
ancillary reading featuring transfer switches:
1)
http://www.ar15.com/forums/t_10_17/661411_Sandy____12_days_without_power__what_worked__what_didn_t____.html
2)
http://www.ar15.com/forums/t_10_17/644329_DIY_Generator_Power_Cables_and_Install.html

ar-jedi








Link Posted: 9/4/2015 8:34:51 PM EDT
[#9]
Question.

If one wanted to install a Cutler-Hammer factory interlock panel/cover; but the top right double breaker spot was occupied currently with a 220V breaker - and the wire for that breaker was not long enough to extend down at all to vacate that spot - is it kosher to extend that wire by adding a junction box and splicing inside it?
Link Posted: 9/4/2015 10:54:58 PM EDT
[#10]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Question.

If one wanted to install a Cutler-Hammer factory interlock panel/cover; but the top right double breaker spot was occupied currently with a 220V breaker - and the wire for that breaker was not long enough to extend down at all to vacate that spot - is it kosher to extend that wire by adding a junction box and splicing inside it?
View Quote


You can remove that wire from the panel, splice it in a junction box and then return to the panel.  You can also splice it in the panel and relocate it to a lower position.   There are fill rules for panels but I doubt you're at that point.
Link Posted: 9/4/2015 11:43:22 PM EDT
[#11]
Discussion ForumsJump to Quoted PostQuote History
Quoted:
Question.

If one wanted to install a Cutler-Hammer factory interlock panel/cover; but the top right double breaker spot was occupied currently with a 220V breaker - and the wire for that breaker was not long enough to extend down at all to vacate that spot - is it kosher to extend that wire by adding a junction box and splicing inside it?
View Quote


simply use a short set of wires and a pair of wire nuts in the panel to extend the two hots, and move the breaker.   in general, however, you want to keep the highest current loads as far up in the panel as possible.  so if you can simply move the two pole breaker (a/c compressor?) down two positions, that is the best case.  but don't sweat it if you have to go farther, even at the bottom of the service panel (farthest away from the POCO feed) is no big deal with a quality panel like your C-H.  

ar-jedi
Link Posted: 9/5/2015 12:05:42 AM EDT
[#12]
It is a 200A service, 32 slot CH panel with 21 of the slots in use.  Top left is double 40A for the AC, top right is double 40A for the range, under that is a double 30A for the dryer - the rest are single slot 20 and 15s (maybe some 10s?).

Been a while since I have had it open, from memory the wires for the range are the only ones w/o enough slack to move the breakers down.

I am still in data collection mode...
Link Posted: 9/5/2015 11:51:24 AM EDT
[#13]
price of screwing it up is too high vs. the price of doing it right
Link Posted: 9/5/2015 12:31:11 PM EDT
[#14]
Link Posted: 9/7/2015 3:50:08 PM EDT
[#15]
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Quoted:
I did it that way for 18 days after hurricane Wilma.  It works, but you have to respect it and be careful.  

- Remember that by doing it that way the male pins on the plug leading to the dryer outlet are hot.  It's easy to forget because male pins are never supposed to be hot.
- Remember that you MUST shut off your main disconnect and preferably lock it out.  

Follow a procedure:
Main disconnect OFF and locked out
Dryer breaker OFF
load breakers OFF
Plug cord in to generator and outlet
Start generator and allow to stabilize
Turn dryer breaker on
Then slowly add loads

ETA:
Shutdown Procedure:
Dryer breaker OFF
Shutdown generator
Unplug

DO NOT shut down the generator when it is under load.






 
View Quote


Why is it bad to shut down under load, may be it ran out of gas, just asking, your procedure looks good.
Link Posted: 9/8/2015 7:50:30 PM EDT
[#16]
When that happens, power is still feeding your appliances, but engine speed is slowing down. So Hz drops, voltage goes crazy. It's called a brown out, and it's WAY worse for electrical stuff (especially electronics) than a black out (cutting power).

Discussion ForumsJump to Quoted PostQuote History
Quoted:


Why is it bad to shut down under load, may be it ran out of gas, just asking, your procedure looks good.
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Quoted:
Quoted:
I did it that way for 18 days after hurricane Wilma.  It works, but you have to respect it and be careful.  

- Remember that by doing it that way the male pins on the plug leading to the dryer outlet are hot.  It's easy to forget because male pins are never supposed to be hot.
- Remember that you MUST shut off your main disconnect and preferably lock it out.  

Follow a procedure:
Main disconnect OFF and locked out
Dryer breaker OFF
load breakers OFF
Plug cord in to generator and outlet
Start generator and allow to stabilize
Turn dryer breaker on
Then slowly add loads

ETA:
Shutdown Procedure:
Dryer breaker OFF
Shutdown generator
Unplug

DO NOT shut down the generator when it is under load.






 


Why is it bad to shut down under load, may be it ran out of gas, just asking, your procedure looks good.

Link Posted: 9/8/2015 7:52:54 PM EDT
[#17]

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Quoted:


Interlock panel.  Lots of good reasons to do it.  No good reason not to.
View Quote
+1

 





Link Posted: 9/8/2015 8:44:15 PM EDT
[#18]
A ten-circuit 30A transfer switch is under $400 on Amazon.  It's what I did...
Link Posted: 9/9/2015 7:41:11 PM EDT
[#19]
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Perfectly put.
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price of screwing it up is too high vs. the price of doing it right


Perfectly put.



Reminds me of a quote by Red Adair.

If you think it's expensive to hire a professional to do the job, wait until you hire an amateur.
Link Posted: 9/9/2015 7:48:31 PM EDT
[#20]
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Quoted:
When that happens, power is still feeding your appliances, but engine speed is slowing down. So Hz drops, voltage goes crazy. It's called a brown out, and it's WAY worse for electrical stuff (especially electronics) than a black out (cutting power).


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Quoted:
When that happens, power is still feeding your appliances, but engine speed is slowing down. So Hz drops, voltage goes crazy. It's called a brown out, and it's WAY worse for electrical stuff (especially electronics) than a black out (cutting power).

Quoted:
Quoted:
I did it that way for 18 days after hurricane Wilma.  It works, but you have to respect it and be careful.  

- Remember that by doing it that way the male pins on the plug leading to the dryer outlet are hot.  It's easy to forget because male pins are never supposed to be hot.
- Remember that you MUST shut off your main disconnect and preferably lock it out.  

Follow a procedure:
Main disconnect OFF and locked out
Dryer breaker OFF
load breakers OFF
Plug cord in to generator and outlet
Start generator and allow to stabilize
Turn dryer breaker on
Then slowly add loads

ETA:
Shutdown Procedure:
Dryer breaker OFF
Shutdown generator
Unplug

DO NOT shut down the generator when it is under load.






 


Why is it bad to shut down under load, may be it ran out of gas, just asking, your procedure looks good.



And turning off large loads on a generator is a great way to damage the voltage regulator.

Turn the smaller breakers off one-by-one seconds apart.

Turning them on that way is easier on things also.

i used to run BIG generators.
Most diesel-electric, a few turbo-generators.

The turbos could burn just about anything including vegetable oil.
Just adjust the jets and pressure feeding the combustion section.


Link Posted: 9/12/2015 6:11:11 PM EDT
[#21]
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Quoted:
We have prohibition from posting illegal activities.  Back feeding without interlock or other code approved safety devices is illegal.
View Quote



NEC ain't law.
Link Posted: 9/17/2015 7:36:15 AM EDT
[#22]
If the panel is full, is there still a way to install a transfer switch?
Link Posted: 9/17/2015 8:57:19 AM EDT
[#23]
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Quoted:
If the panel is full, is there still a way to install a transfer switch?
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with an external transfer switch (such as pictured above) it does not matter that the seevice panel is filled with breakers.
with an interlock plate, 2 breaker spaces are needed (which can often be made using tandem breakers).

ar-jedi
Link Posted: 9/30/2015 8:18:35 PM EDT
[#24]
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?  The sub-panel is connected to the main panel at a 50A breaker.  What size breaker for a 20A generator?  It's a 6kw 21A max generator according the to metal plate on it (is that still considered 20A)?  Most 20A power inlet boxes I see say 5k max wattage.  I haven't seen one higher at 20A.
Link Posted: 9/30/2015 9:10:25 PM EDT
[#25]
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Quoted:
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?
View Quote


no.

ar-jedi
Link Posted: 9/30/2015 9:16:14 PM EDT
[#26]
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Quoted:


no.

ar-jedi
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Quoted:
Quoted:
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?


no.

ar-jedi



Why wouldn't that work, vs backfeeding through a dryer plug on the main panel, if all the breakers on the sub panel were off.
Link Posted: 9/30/2015 9:20:51 PM EDT
[#27]
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Quoted:


Why wouldn't that work, vs backfeeding through a dryer plug on the main panel, if all the breakers on the sub panel were off.
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Quoted:
Quoted:
Quoted:
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?

no.


Why wouldn't that work, vs backfeeding through a dryer plug on the main panel, if all the breakers on the sub panel were off.


what prevents the service drop (from the POCO) *and* the generator (via the subpanel) from both feeding the main service panel at the same time?  (note: undesirable results occur...)

ar-jedi

Link Posted: 9/30/2015 9:28:52 PM EDT
[#28]
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Quoted:


what prevents the service drop (from the POCO) *and* the generator (via the subpanel) from both feeding the main service panel at the same time?  (note: undesirable results occur...)

ar-jedi

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Quoted:
Quoted:
Quoted:
Quoted:
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?

no.


Why wouldn't that work, vs backfeeding through a dryer plug on the main panel, if all the breakers on the sub panel were off.


what prevents the service drop (from the POCO) *and* the generator (via the subpanel) from both feeding the main service panel at the same time?  (note: undesirable results occur...)

ar-jedi



main breaker is off.  Cannot install an interlock on main panel.  Panel is full, hence the sub-panel.
Link Posted: 9/30/2015 9:35:15 PM EDT
[#29]
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Quoted:


main breaker is off.  Cannot install an interlock on main panel.  Panel is full, hence the sub-panel.
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Quoted:
Quoted:
Quoted:
Quoted:
Quoted:
I have an open 2 pole breaker slot on a sub-panel, can I run the generator to a breaker there, and feed the main panel that way?

no.


Why wouldn't that work, vs backfeeding through a dryer plug on the main panel, if all the breakers on the sub panel were off.


what prevents the service drop (from the POCO) *and* the generator (via the subpanel) from both feeding the main service panel at the same time?  (note: undesirable results occur...)



main breaker is off.  Cannot install an interlock on main panel.  Panel is full, hence the sub-panel.


ok perhaps i'm answering the wrong question here.

you can not engineer an interlocked setup the way you describe; nothing prevents the main and generator from being on at the same time, which will have catastrophic effects.  
you can of course bring power from the sub-panel to the main service panel in a myriad of ways, but not in any manner that is safely interlocked.

ps
you have a couple more aspects to consider -- primarily, is the generator a 120Vac-only output, or is a 120/240Vac split phase output.  

ar-jedi
Link Posted: 9/30/2015 9:59:13 PM EDT
[#30]
My finger and brain?  This is a gun forum, what prevents me from shooting myself or neighbors?  Finger and brain.  Assume the main is off in all things generator related.  Would it work?

I would run the 240V L14-20R from the Generator through a power inlet box to a breaker on the sub panel, ALL breakers off, especially the main.  Start the genny, stabilize, throw breaker from inlet.  Throw breaker to main panel.  Add load breakers, seconds apart.
Link Posted: 9/30/2015 10:35:17 PM EDT
[#31]
Go ahead and backfired a sub panel without interlock. After all it isn't illegal per some inter web sexual intellectuals. I don't pay your electric bills anyhow.
Link Posted: 9/30/2015 11:05:52 PM EDT
[#32]
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Quoted:
My finger and brain?  This is a gun forum, what prevents me from shooting myself or neighbors?  Finger and brain.  Assume the main is off in all things generator related.  Would it work?

I would run the 240V L14-20R from the Generator through a power inlet box to a breaker on the sub panel, ALL breakers off, especially the main.  Start the genny, stabilize, throw breaker from inlet.  Throw breaker to main panel.  Add load breakers, seconds apart.
View Quote



Instead of doing something dangerous and backwards why not do it the right way. You can move two breakers from your main panel to your sub panel there by making space for an interlock or you could add one of those small sub panels that are made to be feed from both the main line and the generator like these.

http://www.northerntool.com/shop/tools/product_200196674_200196674

Remember if you do this the dumb backward way and something happens you could end up in trouble with the law or cause damage to your house that your insurance would not pay for.
Link Posted: 10/1/2015 3:18:37 AM EDT
[#33]
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Quoted:
My finger and brain?  This is a gun forum, what prevents me from shooting myself or neighbors?  Finger and brain.  Assume the main is off in all things generator related.  Would it work?

I would run the 240V L14-20R from the Generator through a power inlet box to a breaker on the sub panel, ALL breakers off, especially the main.  Start the genny, stabilize, throw breaker from inlet.  Throw breaker to main panel.  Add load breakers, seconds apart.
View Quote




You could set up targets with your neighbor's house as a backstop and shoot away.  Nothing bad might happen....but then again, you might kill one of your neighbors.  So, it's not recommended.  

Why do it in such a convoluted manner when you can buy a simple transfer switch for a few important circuits and it be safe and proper?   Probably pay the same price or close to what you are proposing.  

Could you do it the way you propose?  Yes.  Should you do it in the manner you propose?  Absolutely not.

You don't need any more breaker spaces if you buy a proper transfer switch.  You only need that extra breaker if you are using an interlock kit.  If you don't have room in your panel or can't get an interlock kit for your panel, then the answer is simple.  Just buy a 5 circuit or so transfer switch, wire it up, and know that you've done it correctly and there is zero risk of injuring yourself, your loved ones, or your house.
Link Posted: 10/3/2015 11:44:18 AM EDT
[#34]
There are numerable sub-panels that have interlocks available for a 'main' input and one of the slots in the panel as another input.

They are often a sheet metal slide that only allows one of the two breakers to be closed at a time.

A vertical top main input and the left side top breaker are common combinations.

A breaker that is being used as a back fed input must be fastened into the panel with a screw. Not just simply snapped in.
Link Posted: 10/4/2015 10:29:25 AM EDT
[#35]
I am NOT recommending you do anything that is unsafe
I am NOT making any judgement as to whether you are a "qualified person"
I am NOT assuming that you can make your particular installation inaccessible to unqualified persons
I am NOT judging your ability to write out clear instructions and post them
I am NOT assuming that you have a way to apply a lockable disconnect or to remove normal supply conductors
I am NOT assuming that, if you read ... that you will read down to the "exception" at the end of this NEC Article (italic font added for clarity)

Just please don't make a blanket statement that something is "illegal"

Stay safe


From the National Electrical Code (quoted from Mike Holt website)  ...

Optional Standby Systems

702.6 Transfer Equipment

Part I. General

A new exception exempts transfer equipment for the temporary connection of a portable generator, but only under restricted conditions.

A transfer switch is required for all fixed or portable optional standby power systems to prevent the interconnection of normal and alternate sources of supply.

Ex: Temporary connection of a portable generator without transfer equipment is permitted, where written safety procedures are in place and conditions of maintenance and supervision ensure that only qualified persons will service the installation, and where the normal supply is physically isolated by a lockable disconnecting means or by the disconnection of the normal supply conductors.
Link Posted: 10/4/2015 12:36:43 PM EDT
[#36]
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Quoted:
I am NOT recommending you do anything that is unsafe
I am NOT making any judgement as to whether you are a "qualified person"
I am NOT assuming that you can make your particular installation inaccessible to unqualified persons
I am NOT judging your ability to write out clear instructions and post them
I am NOT assuming that you have a way to apply a lockable disconnect or to remove normal supply conductors
I am NOT assuming that, if you read ... that you will read down to the "exception" at the end of this NEC Article (italic font added for clarity)

Just please don't make a blanket statement that something is "illegal"

Stay safe


From the National Electrical Code (quoted from Mike Holt website)  ...

Optional Standby Systems

702.6 Transfer Equipment

Part I. General

A new exception exempts transfer equipment for the temporary connection of a portable generator, but only under restricted conditions.

A transfer switch is required for all fixed or portable optional standby power systems to prevent the interconnection of normal and alternate sources of supply.

Ex: Temporary connection of a portable generator without transfer equipment is permitted, where written safety procedures are in place and conditions of maintenance and supervision ensure that only qualified persons will service the installation, and where the normal supply is physically isolated by a lockable disconnecting means or by the disconnection of the normal supply conductors.
View Quote


translation:
You cannot do it in a residence.
Codes have the force of law behind them when adopted.
Link Posted: 10/4/2015 12:53:01 PM EDT
[#37]
slightly related...what size generator would you need to power a 1.5 ton A/C unit?  We planned on only running the A/C for a detached game room during hurricane outages as opposed to the 6 ton main house unit.  I've been told that most large portable generators can't handle the unit's needs at startup....
Link Posted: 10/4/2015 2:39:54 PM EDT
[#38]

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Quoted:


slightly related...what size generator would you need to power a 1.5 ton A/C unit?  We planned on only running the A/C for a detached game room during hurricane outages as opposed to the 6 ton main house unit.  I've been told that most large portable generators can't handle the unit's needs at startup....
View Quote
1.5 tons of AC is equal to 5.25 kW of heat moved from inside the house.  Going with a cofficient of performance of say 2, meaning for each kW of power consumed, there is 2kW of heat moved, it would be 2.625 kW of electric power.  But you have a good sized compressor, blower and fan so figure on at least a 4 kW generator.  If you are going cheap, you will need a 5 kW generator.



My 5kW military surplus generator will easily swing a 4 ton load but it weighs 1100 pounds, has a 70 cubic inch Diesel engine and spins at 1800 RPM.  It will power 8.5 kW load bank without drooping frequency below 59 Hz.  A 5 kW consumer generator will have a 25 cubic inch singl cylindr gas engine turning at 3600 RPM and weigh about 110 pounds.  And it will droop frequency to 55 Hz at rated load.
Link Posted: 10/4/2015 2:41:41 PM EDT
[#39]
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Quoted:
slightly related...what size generator would you need to power a 1.5 ton A/C unit?  
View Quote

there is a label on the side of the unit.  find it.
is it a 120Vac or 240Vac unit?
what are the running amps *and* LRA (locked rotor amps)?
what size breaker is feeding it now?

ar-jedi
Link Posted: 10/4/2015 5:14:01 PM EDT
[#40]
Discussion ForumsJump to Quoted PostQuote History



From the National Electrical Code (quoted from Mike Holt website)  ...

Optional Standby Systems

702.6 Transfer Equipment

Part I. General

A new exception exempts transfer equipment for the temporary connection of a portable generator, but only under restricted conditions.

A transfer switch is required for all fixed or portable optional standby power systems to prevent the interconnection of normal and alternate sources of supply.

Ex: [span style='font-style: italic;']Temporary connection of a portable generator without transfer equipment is permitted, where written safety procedures are in place and conditions of maintenance and supervision ensure that only qualified persons will service the installation, and where the normal supply is physically isolated by a lockable disconnecting means or by the disconnection of the normal supply conductors.
View Quote


What year of the NEC? What year NEC is adopted by the OP's state? I know Florida adopted the 2011 NEC. The way I read that, an interlock device is required to prevent the main breaker being closed at the same time as the gen. Didn't the OP say there's no room for an interlock?
Link Posted: 10/4/2015 8:27:42 PM EDT
[#41]
Link Posted: 10/4/2015 11:49:34 PM EDT
[#42]
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Quoted:
Didn't the OP say there's no room for an interlock?
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if there is no room in the current service panel, there are *at least* two options:

1) use an external transfer switch --> http://www.ar15.com/forums/t_1_139/1782712_Backfeeding_your_house_with_a_generator_and_a_dryer_outlet_.html&page=3#i55456596
2) in the current service panel, replace 4 full height breakers with 2 tandem breakers -- this will free up 2 slots, to which the interlock can be applied.

ar-jedi

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