Custom Junction box

[Maxxy41]

Hey all. I have a few 3” pipes I ran across my garage under the concrete corner to corner. They all end on the wall right next to my panel

They’re large (3” pvc”) because I got it for free. I’m planning on having them all pipe into a large junction box or end box then connect it to my panel with a few offsets

I’m searching for a decently priced junction box/end box or a wiring trough but they’re all pretty expensive

Can I use any old box (metal or pvc) as a junction box or is it limited to specific equipment?

For example a metal cabinet. I’ve found a metal fire extinguisher box with a full metal door. Or a friend joked about a metal tool box.

Also when I connect it to my panel should I play it safe and just run 3/4” or can I do a larger size. I’m not sure the ruling on how many conductors or circuits through one conduit

 

[coop3339]

There is a limit to how many conductors you can put in a conduit. Also if you have more than 3 current carrying conductors in one conduit you have to derate. Unless its under 24" in length. Electrical equipment must be Listed for its use by a testing agency like UL. I'm not certain this a requirement for junction or splice boxes but I believe it is. A 4x4x18 or 24 gutter may be a good choice. Nema type 1 for indoor use are not too expensive. you could use some of the scrap conduit to make a nipple to connect it to the breaker box. As an alternative you could look for something used or extra on ebay to save some cash.

 

[don_resqcapt19]

There is a limit to how many conductors you can put in a conduit. Also if you have more than 3 current carrying conductors in one conduit you have to derate. Unless its under 24" in length. Electrical equipment must be Listed for its use by a testing agency like UL. I'm not certain this a requirement for junction or splice boxes but I believe it is. A 4x4x18 or 24 gutter may be a good choice. Nema type 1 for indoor use are not too expensive. you could use some of the scrap conduit to make a nipple to connect it to the breaker box. As an alternative you could look for something used or extra on ebay to save some cash.

The NEC does not require all electrical equipment to be listed.
Junction boxes can be covered by Article 312 or Article 314. Article 312 does not have a listing requirement, and Article 314 only requires enclosures that are used in wet locations to be listed.

 

[kwired]

You can't pull individual conductors through this pipe if it is not a listed raceway type. You can use it as a sleeve and pull cables through it, but are subject to ampacity adjustments because of "bundling" effects. Also since below the garage floor (assuming slab on grade placing this underground) it would need to be a cable rated for wet locations - so NM cable is not acceptable. UF cable would be.