The company I work for is doing a 4 story courthouse/justice center. MDP is in the basement. each floor has 3 electrical rooms on them. Each high voltage panel is a M.L.O. panel. Isn't there somewhere in the code that say's panels either 50' away or not within sight of main breaker (which would be in the MDP) of that panel must have a main breaker and can't be M.L.O.? Also someone mentioned that in the new code you can not run two 3 phase circuits in a conduit. We have 3 phase reheats on each floor and they said that each reheat would have to have a separate conduit run to it and can not pair two of them up.
main breaker or M.L.O.
- Thread starter elect36
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The company I work for is doing a 4 story courthouse/justice center. MDP is in the basement. each floor has 3 electrical rooms on them. Each high voltage panel is a M.L.O. panel. Isn't there somewhere in the code that say's panels either 50' away or not within sight of main breaker (which would be in the MDP) of that panel must have a main breaker and can't be M.L.O.? Also someone mentioned that in the new code you can not run two 3 phase circuits in a conduit. We have 3 phase reheats on each floor and they said that each reheat would have to have a separate conduit run to it and can not pair two of them up.pierre
Senior Member
- Location
- Westchester County, New York
Re: main breaker or M.L.O.
There is no restriction as to the length of the feeder conductors run to a MLO panel in the building from the OCPD.
I am not aware of the change in the '05 as to restricting more than one 3-wire circuit, that would be a big surprise to me.
Pierre
There is no restriction as to the length of the feeder conductors run to a MLO panel in the building from the OCPD.
I am not aware of the change in the '05 as to restricting more than one 3-wire circuit, that would be a big surprise to me.
Pierre
BAHTAH
Senior Member
- Location
- United States
Re: main breaker or M.L.O.
While there is no code requirement for a main breaker in your installation, one design practice where the panels are located some distance from the service distribution and you want to give the customer a main disconnect he/she can use without having to go to the main equipment is a non-automatic main breaker. In this way the panel has a main switch while not having a breaker at the main board feeding a breaker of the same size at the panel. The non-auto breaker is just a switch and offers no overload, short circuit or ground-fault protection.
While there is no code requirement for a main breaker in your installation, one design practice where the panels are located some distance from the service distribution and you want to give the customer a main disconnect he/she can use without having to go to the main equipment is a non-automatic main breaker. In this way the panel has a main switch while not having a breaker at the main board feeding a breaker of the same size at the panel. The non-auto breaker is just a switch and offers no overload, short circuit or ground-fault protection.
allenwayne
Senior Member
Re: main breaker or M.L.O.
Most disconnects I have seen have some type of lock out device (using them is another story )With this said I assume that a breaker feeding a sub panel must have a lock out as well as a lock down clip if not within sight?interestimg thread
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Most disconnects I have seen have some type of lock out device (using them is another story )With this said I assume that a breaker feeding a sub panel must have a lock out as well as a lock down clip if not within sight?interestimg thread
!!!!!!
- Location
- Illinois
- Occupation
- retired electrician
Re: main breaker or M.L.O.
Don
The code does not require this for a panel.
Don
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