Manual/Automatic transfer switch for Generators in Residential Homes

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dayrongarcia

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Hello,

Is there a code that talks about manual/automatic transfer switches for generators in residential homes?

Am planning to install a back up generator and connected to the house but I need to know if the system must be manually turned on, in other words, someone must be in the house to turn it on if the power goes out.

Thanks
 
Is this for your own house, or are you designing an installation as part of a work-related project?
 
Derek has the code references. But the bottom line is that you could go either way. It is up to the customer to decide, and to pay for, whichever one they want. There are advantages and disadvantages to both. If I am not at home when the power goes out, then there is some value in having automatic backup power source for the fridge and freezer. But then, the generator will eventually run out of fuel, so that advantage is short lived.
 
charlie b said:
Derek has the code references. But the bottom line is that you could go either way. It is up to the customer to decide, and to pay for, whichever one they want. There are advantages and disadvantages to both. If I am not at home when the power goes out, then there is some value in having automatic backup power source for the fridge and freezer. But then, the generator will eventually run out of fuel, so that advantage is short lived.
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Someone told me that the transfer switch had to be manual to make sure someone was there at the time of the switching. I checked the Florida building code and couldn't find anything related to transfer switches for houses. Florida uses nfpa 70, so I don't know where the one who told me got his information. Do you know about this specific case in FL?
 
dayrongarcia said:
Someone told me that the transfer switch had to be manual to make sure someone was there at the time of the switching. I checked the Florida building code and couldn't find anything related to transfer switches for houses. Florida uses nfpa 70, so I don't know where the one who told me got his information. Do you know about this specific case in FL?
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Manual by both design and definition require someone to be there to do the switching. Automatic by design and definition will usually start the generator and do the switching by itself if working properly.

I think whoever told you that is not a very reliable source.
 
dayrongarcia said:
Someone told me that the transfer switch had to be manual to make sure someone was there at the time of the switching. I checked the Florida building code and couldn't find anything related to transfer switches for houses. Florida uses nfpa 70, so I don't know where the one who told me got his information. Do you know about this specific case in FL?
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I live in Florida and have a whole house generator (20kW) with an ATS fueled by natural gas. It passed inspection for Hillsborough County - electrical and gas.
 
charlie b said:
Derek has the code references. But the bottom line is that you could go either way. It is up to the customer to decide, and to pay for, whichever one they want. There are advantages and disadvantages to both. If I am not at home when the power goes out, then there is some value in having automatic backup power source for the fridge and freezer....
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And this is my problem with the 702 requierment added in '08. I don't need a generator sized to carry my whole house when I am not home. If I am not home my load will be very light., and if I am home I can do my own load shedding.
 
ActionDave said:
And this is my problem with the 702 requierment added in '08. I don't need a generator sized to carry my whole house when I am not home. If I am not home my load will be very light., and if I am home I can do my own load shedding.
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Was kind of my thoughts also. It is not an electical safety issue it is an electrical reliability and design issue, even for legally required standby systems IMO this is an issue for other codes and not the NEC - informationial notes pointing to those codes is what is needed.
 
Automatic Transfer Switch is better

Automatic Transfer Switch is better

dayrongarcia said:
Hello,

Is there a code that talks about manual/automatic transfer switches for generators in residential homes?

Am planning to install a back up generator and connected to the house but I need to know if the system must be manually turned on, in other words, someone must be in the house to turn it on if the power goes out.

Thanks
Click to expand...

I think Automatic Transfer Switch "ATS" is better for you. Even if you are not in the house and the utility power goes out, ATS will switch the power automatically to the standby generator and if then the utility power comes back, the same ATS will switch the power again to the utility power and turn the generator off after calling.
For more details about the relation between the standby generators and transfer switch, you can visit the following site: ATS Simply. I think it will be useful for you.
 
ahmedats said:
I think Automatic Transfer Switch "ATS" is better for you. Even if you are not in the house and the utility power goes out, ATS will switch the power automatically to the standby generator and if then the utility power comes back, the same ATS will switch the power again to the utility power and turn the generator off after calling.
For more details about the relation between the standby generators and transfer switch, you can visit the following site: ATS Simply. I think it will be useful for you.
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It really depends how long you can afford to be without power.

A refrigerator or freezer that is fairly full will stay cold for a fair amount of time - especially if nobody is there to open doors and let warm air inside.

If nobody is there for longer periods of time quite frequently the need for automatic protection increases.

Not too many loads in a dwelling are that critical that they need automatic transfer, it is more of a convenience than a need most of the time.
 
dayrongarcia said:
Someone told me that the transfer switch had to be manual to make sure someone was there at the time of the switching. I checked the Florida building code and couldn't find anything related to transfer switches for houses. Florida uses nfpa 70, so I don't know where the one who told me got his information. Do you know about this specific case in FL?
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Are you sure the person that told you this was not thinking about a generator to small to carry the calculated load per the 702 requirement?

Roger
 
kwired said:
Was kind of my thoughts also. It is not an electical safety issue it is an electrical reliability and design issue, even for legally required standby systems IMO this is an issue for other codes and not the NEC - informationial notes pointing to those codes is what is needed.
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The manufacturers claimed it was safety issue, I say if it was they need to design their equipment better.
 
iwire said:
The manufacturers claimed it was safety issue,
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Another fine example of manufacturers being catered too by the NFPA.

Optional standby is just that, there is nothing "safety" about it. if safety is an issue articles 700 and 701 need to be the applicable articles in play.

Roger
 
I'm as cynical as a man can be when it comes to the NEC but you can't hang this one on manufactures alone. A lot of electricians argued the need for the rule change. I debated with them in person and on this forum.
 
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ActionDave said:
I'm as cynical as a man can be when it comes to the NEC but you can't hang this one on manufactures alone. A lot of electricians argued the need for the rule change. I debated with them in person and on this forum.
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Dave, help me out here and point me to all these ROP's. If I remember correctly there weren't that many.

Roger
 
roger said:
Dave, help me out here and point me to all these ROP's. If I remember correctly there weren't that many.

Roger
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I know, I know. I agree with you in both cases. It's a stupid rule, the NEC is more about representing manufactures every cycle. I'm just saying that there are electricians that agree the rule change was needed.
 
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