Manual transfer switch and panel

[steveray]

First one of these I have seen....Here is the situation...100A service comes in, goes to manual transfer switch for the generators that everyone and their brother is putting in these days...work done by licensed electrician....comes out of transfer switch, continues on as 3 wire SEU into service panel......Shouldn't the TS become the first point of disconnect? And all of the grounding go back to it?View attachment 1177View attachment 1178

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[north star]

&

Do the conductors feed to the generator and to the residence normal power,

...out of the transfer switch?.....According to Article 445.18 [`08 NEC ] -

Disconnecting Means For Generators:

"Generators shall be equipped with disconnect(s), lockable in the open position

by means of which the generator and all protective devices and control

apparatus are able to be disconnected entirely from the circuits supplied by

the generator except where both of the following conditions apply.....(1) The

driving means for the generator can be readily shut down, and (2) the

generator is not arranged to operate in parallel with another generator or

other source of voltage."

IMO, it seems that there should have been another set of conductors

feeding the residence normal service panel, so that there can be a

disconnecting means on each......Two sets of conductors would also allow

either set of feeders to be energized independently of each other

and still have a compliant disconnect to each.....If I am seeing your

pics. correctly, the current wiring method could shut the entire

house down from the transfer switch.

According to Article 702, ...the installation of a generator [ as a

backup ] would classify it as an Optional Standby System [ see the

definition of O.S.S. in the NEC ] and therefore necessitate an

option to the user to be able to switch to one or the other "manually".

Kinda like a "bypass" system...

Maybe I'm missing something...

&

 

[raider1]

First one of these I have seen....Here is the situation...100A service comes in, goes to manual transfer switch for the generators that everyone and their brother is putting in these days...work done by licensed electrician....comes out of transfer switch, continues on as 3 wire SEU into service panel......Shouldn't the TS become the first point of disconnect? And all of the grounding go back to it?

View attachment 1177View attachment 1178

The transfer switch must be rated as suitable as service equipment and it must be the service disconnecting means in your situation. You can't have a transfer switch located upstream from the service disconnecting means. See 230.82 for equipment permitted to be located on the supply side of the service disconnecting means.

Chris

 

[JPotter04210]

It looks to me like that particular switch is a double throw switch and as such acts as both the disconnect and alternate generator connection in one; the connections are mutually exclusive, the house panel is connected to either the power company or the generator. But where to install it?

 

[north star]

>

JPotter04210,

Presently, if the disconnect on the [ manual ] transfer switch

is "thrown", how will electrical power be fed to the normal

house circuits?

<

 

[JPotter04210]

It looks to me form the picture, although it is rather small, that the switch has two connections, one to the grid which connects the house panel to the supply gird, and another which connects the house panle to the generator. The switch is 'off' when it is in the middle position and thus not connecting the house panel to either supply. That is how it looks to me but as I said the photo is rathter small and I could easily be mistaken. Bear in mind that I am an engineer and an old 'farm boy', not an electircian!

 

[north star]

* *

I agree that the pics. are small, ...I'll have to issue some

demerits to " steveray " for the diminished quality of the

photos. I am not an electrician either!.....I'm not

even playing one here in this box [ Forum ].....I could

be seeing the photos completely wrong too!



Glad to have you onboard in this forum......Hope you will

continue to post on here, and advertise this site to

your colleagues & peers.

* *

 

[JPotter04210]

I could be wrong but it looks to me like it is a three pole, two position switch. one set of leads is attached to the left (say from the grid) another to the right (say to the generator) while the third is connected to the switch lever itself (say to the panel). So if you throw the switch to the left it would connect the panel to the grid. When thrown to the right it would connect the panel to the generator. While in transit between the two poles nothing is connected. It is an old style switch, simple but effective.

 

[raider1]

I could be wrong but it looks to me like it is a three pole, two position switch. one set of leads is attached to the left (say from the grid) another to the right (say to the generator) while the third is connected to the switch lever itself (say to the panel). So if you throw the switch to the left it would connect the panel to the grid. When thrown to the right it would connect the panel to the generator. While in transit between the two poles nothing is connected. It is an old style switch, simple but effective.

Correct, but it can't be installed on the supply side of the service disconnecting means unless it is service rated and contains fuses or other overcurrent protection.

A simple manual transfer switch such as this must only be installed on the load side of the service disconnecting means.

Chris

 

[steveray]

Thanks Chris and everyone else.....it is service rated, but as you mentioned, no OC protection...I believe you could go into this switch and nipple in to the panel with the main OCPD "immediately adjacent" to the TS (230.91)....but that is no excuse from not seperating the grounds and neutrals at the first point of disconnect....

Sorry about the small pics....i will work on that, the site kept telling me the files were too large, maybe I downsized them too much! I will try to play with them and do better next time!...Short on (play)time these days...