NEMA 4X

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wireday

Senior Member
Location
New England
Occupation
Master electrician
I am using customer supplied parts on a job.I have a small control power box that will be mounted on a wall.The box the customer has is nice,stainless hinged cover.I just was wondering about the 1/4 turn screw lock on the cover.Code wise is that the same as A box with multiple screw clips?Or even a 4X4 with screws that thread in and tighten up. I will have a few exposed live parts in the box.I just have never used this type box before,Thanks
 

wireday

Senior Member
Location
New England
Occupation
Master electrician
The area is used for mixing chemicals.The control box they have is a nema 4x stainless.It just seems easy to open,just a straight slot 1/4 turn,and it opens right up.We will be using it for small components and terminals.It mounted on the wall in a room with people running around mixing chemicals all day.The reason I ask is any code issues.I;m just used to them having clips or screws in each corner.Thanks
 

don_resqcapt19

Moderator
Staff member
Location
Illinois
Occupation
retired electrician
In the past you could tell the difference between a NEMA 4 and a NEMA 12 by the number of cover clamps. The NEMA 4 would have cover clamps on 3 sides and the 12 only on the side opposite the hinge.

Apparently they have found a way to make the single 1/4 turn clamp work for a NEMA 4 application as they are readily available from a number of manufacturers in that design.
 

Jraef

Moderator, OTD
Staff member
Location
San Francisco Bay Area, CA, USA
Occupation
Electrical Engineer
From a "code" standpoint, there are a lot of details missing here for any kind of meaningful discussion. But as a gross generality, and assuming because you mention NEMA that you are talking US codes, the NEC doesn't really address access issues unless there is line power involved. If everything in the box is limited energy, there are no access restriction requirements. If it's just control power, ie 120VAC, there may be depending on circumstances, meaning access may be required to be restricted to "qualified" personnel. If there is line power, it would need a disconnect switch. If it's a machine, article 409 May apply and if it's a machine tool, NFPA 79 may be involved, but this doesn't sound like a machine.

"Controlled access" by the way can often mean nothing more that "have a tool in hand". Then if this has 1/4 turn latches with what's called a "coin slot", you get into the nuances of whether a quarter is a "tool". If it is thumb latches, people often require a lock hasp added to those because of casual accessibility.
 

wireday

Senior Member
Location
New England
Occupation
Master electrician
It is a box for a chemical mixer.120volt, plugs into a receptacle.The VFD requires a line reactor if our supply transformer is over 100k,its 112K.So it goes 120volt plug to this nema4x box with the line reactor,to the VFD then to the mixer motor.
 

Aleman

Senior Member
Location
Southern Ca, USA
There are plenty of Nema 4X boxes with single latches. It's nothing to worry about. If the box is rated 4X then that is what it is.
I like the single latches because it's easy to open them with the side of a key if you don't have a screwdriver on you.
 
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