Davebones
Senior Member
- Location
- North Of Tampa Fl
Manager wants 250 V 3 phase outlets thru out lab area for test chambers . Does the nec require disconnect before outlet ? Does Arc Flash hazards require disconnect ?
50 amp outlets
- Thread starter Davebones
- Start date
- Status
Assuming you are referencing receptacle outlets, f you are dealing with a hazardous location, more discussion is warranted. If not, I know of no NEC application that requires a disconnect at a receptacle outlet.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
A receptacle IS a disconnect.
A receptacle is listed as a disconnect device?
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
Thanks!
I'll copy that here for the OP:
422.33 Disconnection of Cord-and-Plug-Connected Appliances.
(A) Separable Connector or an Attachment Plug and
Receptacle. For cord-and-plug-connected appliances, an
accessible separable connector or an accessible plug and
receptacle shall be permitted to serve as the disconnecting
means. Where the separable connector or plug and receptacle
are not accessible, cord-and-plug-connected appliances
shall be provided with disconnecting means in accordance
with 422.31.
Davebones
Senior Member
- Location
- North Of Tampa Fl
Agree that the NEC says this is a means of disconnect . Have heard that if you look at NFPA 70E that you would need PPE if plugging in while this is rec is energized . This is a standard " Plug and Sleeve " 50 amp circuit . I know that there is the decontactor type plugs that interrupt the load before removing the plug . Don't want to get into argument about " unplugging a 120 V outlet " . These are 50 amp outlets for welder's and test chambers . Just looking for futher opinions about 70E and if PPE is required ...
The NEC is specific as far as where a receptacle can be recognized as a disconnecting means/device such as the aforementioned article section as well as at least one more and some exceptions but, this is not across the board and not all receptacles are listed for making and breaking a load such as Meltric receptacles are.
So in some cases a disconnect ahead of a receptacle could be necessary
Roger
So in some cases a disconnect ahead of a receptacle could be necessary
Roger
I have been talking with our engineers and suggested they incorporate a Meltric style decontactors into their new projects if feasible. It is more expensive, but feel it helps align us more with 70E. We have large 480v 3p equipment that our folks are having to plug in energized and it's never made me comfortable.
http://www.meltric.com/html/decontactor-plugs-receptacles.html
renosteinke
Senior Member
- Location
- NE Arkansas
"A receptacle is a disconnect ..."
If only it were that simple.
It's not a problem at the lower amperages, but once you get past 30 amps you really need to start looking at your plug and receptacle details. Not every plug is rated for the maximum horsepower, and you can get some pretty good arcs when you have a 480v motor bind up and you pull the plug.
That's why a lot of the special receptacles are designed to shut the power off before you can pull the plug out. That's also part of the reason there are so many different plug designs.
If only it were that simple.
It's not a problem at the lower amperages, but once you get past 30 amps you really need to start looking at your plug and receptacle details. Not every plug is rated for the maximum horsepower, and you can get some pretty good arcs when you have a 480v motor bind up and you pull the plug.
That's why a lot of the special receptacles are designed to shut the power off before you can pull the plug out. That's also part of the reason there are so many different plug designs.
- Status