On a 6 circuit manual transfer switch, why do you have to connect both circuits of a multi-wire circuit to the tranfer switch. I understand balancing the generator load, if your using both circuits, and in that case why you connect a mutiwire circuit on opposing phases of the generator, but if you are just using one circuit of a multi-wire circuit will there be any neutral problem?
Generator Transfer Switch
- Thread starter jot30
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LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
jot30 said:
I have never heard this, and no, it should not be an issue.
Transfer Switch
Transfer Switch
I came across the multi-wire circuit note when I was installing a Reliance Control 6 position manual transfer switch. You can find the manual on line if you google Reliance Control tranfers switch. I am trying to contact them for clarification, but I thought someone may have already encountered this same note.
Thanks for the replies
Transfer Switch
I came across the multi-wire circuit note when I was installing a Reliance Control 6 position manual transfer switch. You can find the manual on line if you google Reliance Control tranfers switch. I am trying to contact them for clarification, but I thought someone may have already encountered this same note.
Thanks for the replies
- Location
- Massachusetts
jot30 said:
Because the NEC requires it.
From the 2002 but the 2005 has it as well
A 6 circuit manual transfer switch is really a panel board as it provides the overcurrent protection as well.
Muti-wire circuit
Muti-wire circuit
But in the Line position of this 3 position transfer switch; Line, Off, Gen, the overprotection is accomplished with the breaker in the main panel...not the transfer panel. So again if you are in the Gen position operating off generator power....if you aren't using the other circuit of the muti-wire circuit...is there a neutral overload problem
Muti-wire circuit
But in the Line position of this 3 position transfer switch; Line, Off, Gen, the overprotection is accomplished with the breaker in the main panel...not the transfer panel. So again if you are in the Gen position operating off generator power....if you aren't using the other circuit of the muti-wire circuit...is there a neutral overload problem
- Location
- Massachusetts
jot30 said:
You lost me.
The bottom line is you must use it and install it as instructured per 110.3(B), rest assured they would not tell you in the instructions to create an unsafe condition.
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1793
Senior Member
- Location
- Louisville, Kentucky
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- Inspector
I have been reading this thread and I'm still a little confused as to why there would be a "neutral overload" if only one hot of a multiwire circuit is used. The neutral should be sized for the circuit ampacity of the largest circuit so I don't see how using just one circuit would cause an overload.
The neutral, as I see it, would be overloaded if the two circuits were operating on the same phase.
What am I missing?
1793
1793
That was what I also thought...... I realize that if I am using both circuits of the multi-wire circuit on, Gen power, that they must be on opposite phases. I just did not understand how they worded the note. You can read the note in their manual on their website. It's the same version of the hard copy you get with the product reliancecontrols.com - product information. I have been installing the transfer switch as they recommend, but I try to avoid multi-wire circuits.
Thanks for the help. I check out this forum from time to time, but this is my first post.
1793
That was what I also thought...... I realize that if I am using both circuits of the multi-wire circuit on, Gen power, that they must be on opposite phases. I just did not understand how they worded the note. You can read the note in their manual on their website. It's the same version of the hard copy you get with the product reliancecontrols.com - product information. I have been installing the transfer switch as they recommend, but I try to avoid multi-wire circuits.
Thanks for the help. I check out this forum from time to time, but this is my first post.
Pierre C Belarge
Senior Member
- Location
- Westchester County, New York
Jot30
Welcome to the site/posting!
Welcome to the site/posting!
LarryFine
Master Electrician Electric Contractor Richmond VA
- Location
- Henrico County, VA
- Occupation
- Electrical Contractor
There are two types of multi-circuit T/S panels:
The first one has two conductors for each circuit, one supply and one 'return', each circuit's switch is an SPDT type, and the circuit uses the original breakers in normal mode, and the T/S's breaker in generator mode.
The other has a single pair of conductors for the normal power supply, like a sub-panel, and the T/S's breakers are used in both normal and generator modes. Sometimes, the home runs are rerouted to the T/S.
Both types have a single neutral conductor and an EGC conductor, and you must maintain opposing phases when supplying MWBC's, but supplying only one conductor is no different than turning off only one breaker of a MWBC.
Either way, as long as everything is wired properly, there is no electrical reason to bring non-necessary conductors in or through the T/S's enclosure or raceway. BTW, I have never seen any instructions stating to do so.
"We've always done it that way!"
The first one has two conductors for each circuit, one supply and one 'return', each circuit's switch is an SPDT type, and the circuit uses the original breakers in normal mode, and the T/S's breaker in generator mode.
The other has a single pair of conductors for the normal power supply, like a sub-panel, and the T/S's breakers are used in both normal and generator modes. Sometimes, the home runs are rerouted to the T/S.
Both types have a single neutral conductor and an EGC conductor, and you must maintain opposing phases when supplying MWBC's, but supplying only one conductor is no different than turning off only one breaker of a MWBC.
Either way, as long as everything is wired properly, there is no electrical reason to bring non-necessary conductors in or through the T/S's enclosure or raceway. BTW, I have never seen any instructions stating to do so.
"We've always done it that way!"
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