How to find the center of a conduit in panel layout

[Jwk7525]

How to do you find the center of a conduit for layout of a panel. I have a spacing chart but can't remember the centers for 1/2 up to 4. Thanks

 

[infinity]

A general rule of thumb without getting too precise 1/2"-2" KO add 3/8" to the trade size for the KO diameter. 2.5"-4" add 1/2" to the trade size for the KO diameter. When in doubt you can just measure the cutter on the KO punch.

 

[kwired]

A general rule of thumb without getting too precise 1/2"-2" KO add 3/8" to the trade size for the KO diameter. 2.5"-4" add 1/2" to the trade size for the KO diameter. When in doubt you can just measure the cutter on the KO punch.

Do not measure cutter, measure the larger "die" this allows for space for locknuts, fittings, etc that are larger then the raceway itself. But do keep in mind that still may not be enough space for all fittings.

 

[dibloafer]

In a pinch, just lay out your lock nuts in a row across top of the panel where they are going to be punched-allowing enough space to be tight but also be able to thread them onto the connector w/o it being a PITA. Mark all of your center lines for each lock nut perpendicularly and away you go.

 

[Smart $]

A general rule of thumb without getting too precise 1/2"-2-1/2" KO add 3/8" to the trade size for the KO diameter. 3"-4" add 1/2" to the trade size for the KO diameter.

FIFY

If you want to verify: https://greenlee-cdn.ebizcdn.com/media/2015 Knockouts.pdf

When in doubt you can just measure the cutter on the KO punch.

And if one needs the radius (1/2 the diameter :angel of the conduit, surely a piece of the size you are punching a hole for is laying around to measure.

 

[infinity]

And if one needs the radius (1/2 the diameter :angel of the conduit, surely a piece of the size you are punching a hole for is laying around to measure.

You can do that too but that doesn't work with EMT until you get to 2.5" and larger that's why I suggested measuring the actually cutter to get the size of the KO not the raceway.

For me I always layout the outside of the KO's with the desired space in between. I do not layout using the centers.

 

[K8MHZ]

In a pinch, just lay out your lock nuts in a row across top of the panel where they are going to be punched-allowing enough space to be tight but also be able to thread them onto the connector w/o it being a PITA. Mark all of your center lines for each lock nut perpendicularly and away you go.

Good technique. A set of perfect centers means nothing if you can't spin the locknuts.

 

[Smart $]

And if one needs the radius (1/2 the diameter :angel of the conduit, surely a piece of the size you are punching a hole for is laying around to measure.

You can do that too but that doesn't work with EMT until you get to 2.5" and larger that's why I suggested measuring the actually cutter to get the size of the KO not the raceway.

Butttt... he didn't ask for the center of the KO. He asked for the center of the conduit...

How to do you find the center of a conduit for layout of a panel. ...

...although they're supposed to be the same in the layout. If you layout say a bunch of KO's for 3/4" EMT held off the wall by deep strut, the center is 1-5/8" + 0.461"... approximately 2-1/16". If you go by the back of the KO, that puts the center at 2-3/16". A difference of 1/8". Now a lot of electricians will tell you an 1/8" in electrical work is tolerable. In many cases it is... but that does not mean I'll lay it out with the 1/8" built into it. :happyno:

 

[kwired]

Butttt... he didn't ask for the center of the KO. He asked for the center of the conduit......although they're supposed to be the same in the layout. If you layout say a bunch of KO's for 3/4" EMT held off the wall by deep strut, the center is 1-5/8" + 0.461"... approximately 2-1/16". If you go by the back of the KO, that puts the center at 2-3/16". A difference of 1/8". Now a lot of electricians will tell you an 1/8" in electrical work is tolerable. In many cases it is... but that does not mean I'll lay it out with the 1/8" built into it. :happyno:

Next thing that throws you off is you measure from back wall of the cabinet, and forget the mounting holes in the back of the box make it stand an additional 1/4 inch off the mounting surface. If you were already off by an 1/8 inch that can give you a net error of either 1/8 or 3/8, depending on which way you were off.

 

[infinity]

Butttt... he didn't ask for the center of the KO. He asked for the center of the conduit......although they're supposed to be the same in the layout. If you layout say a bunch of KO's for 3/4" EMT held off the wall by deep strut, the center is 1-5/8" + 0.461"... approximately 2-1/16". If you go by the back of the KO, that puts the center at 2-3/16". A difference of 1/8". Now a lot of electricians will tell you an 1/8" in electrical work is tolerable. In many cases it is... but that does not mean I'll lay it out with the 1/8" built into it. :happyno:

You're correct he did ask about centers. For me 1/8" off will make the conduit out of plumb will look pretty crooked when coming down an wall into the panel.

 

[K8MHZ]

Next thing that throws you off is you measure from back wall of the cabinet, and forget the mounting holes in the back of the box make it stand an additional 1/4 inch off the mounting surface. If you were already off by an 1/8 inch that can give you a net error of either 1/8 or 3/8, depending on which way you were off.

Also, don't forget the bend radius of the sheet metal so you don't put the holes to close to the inner walls.

 

[Smart $]

Next thing that throws you off is you measure from back wall of the cabinet, and forget the mounting holes in the back of the box make it stand an additional 1/4 inch off the mounting surface. If you were already off by an 1/8 inch that can give you a net error of either 1/8 or 3/8, depending on which way you were off.

Correct. One must take all 'offsets' into account for an accurate layout.