Hello! We are working on converting our Sprinter van into a camper van. Right now we are working on our electrical. The junction box we got doesn’t fit our 2/0 cable like it should. And the 250 MCM lugs we got doesn’t fit the 250 MCM cable like it should either. So we are needing some help making the holes slightly bigger on those items since they can’t be returned. Does anyone know what machine should be used, how to use the machine, or if a class has to be taken to use the machine? Is anyone going to be around today who can show/help us in person?
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The holes will have to all be drilled out a minimum of the thread diameter plus a a couple thousands until the hole is clean and smooth.
Then you throw away all the screws that were in them and replace them with the next size up closest to the new hole size. They should be the same type of material as the screws that are removed due to thermal expansion and avoid a fire hazard. That might be tricky
Then retap the holes to match the new screw sizes. Where this now gets tricky is the wall thickness between the two holes will be reduced by the difference in the diameters. You may be okay, but there is not as much material there to take the load.
It’s maybe doable. When you get ready to use new screws, when selecting the closest size look for what’s available in Metric and Inches (electricity doesn’t care) so you remove the least amount of material, may have to drills and buy taps to match.
Not sure how much the electrical load will be, but those look like stout cables, for safety reasons - I suggest buying replacements rather than risk an untoward event with worked over connectors.
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I’m with you here, and will echo the sentiment that in general, if the lug is intended to be used with the wire, it will fit. Trying to “shoehorn” stuff into place can be a recipe for disaster.
However, I don’t think drilling and tapping the screw holes is needed. They need to enlargen the sooth-bore holes where the wires go.
The photos show the screw-down lugs, which should be easy enough to drill with a drill press, or on the Bridgeport and a vice. Finding the center would be the hardest part, but could be easily enough done with a cone bit.
As for the crimp-on connector… if you need to make the bolt hole bigger, same procedure/process. If you are wanting to make the crimp part bigger, you’d want to swage that. But I would steer clear of that except as an emergency repair. I am not aware of a swage/expanding tool to do that for this type of application; usually they’re meant for plumbing fixtures. Maybe someone else is, or maybe you can find and press into service a plumbing tool.
I have re-iterate, though, that I wouldn’t do any of this except as an emergency stopgap. You just don’t want to scrimp here, and watch your Sprinter home go up in smoke due to mis-use of a simple electrical connection. (Which is not to say I haven’t been there, and done that, and it’s been just fine: still can’t recommend it).
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Yea I don’t think we will need to drill and tap the screw holes, just the 3 holes on the bottom (or top if it will be easier) of each block where the wires are going to go. We only need to make the holes just a smidgen bigger. I can fit about 15/16 of the wire into the hole. The junction box stated it was 2/0 holes, so its frustrating that it doesn’t fit. I have also looked everywhere on the web and can’t find a similar junction box with slightly larger holes, so that is why I am opting to just make them bigger. I do agree with you though, I definitely don’t want to scrimp out here. I am open to any and all suggestions.
Have you considered thinning the end of the wire slightly ? As in trim a few strands from each bundle.
If it’s very close to fitting already, it shouldn’t take much, and I doubt that would lower current carrying capacity by any significant amount. ( At least as long as you only remove a little. 1/16 of the total as you note above should be ok. )
Cannot recommend trimming any wires off either for the same reason as I can’t recommend enlarging the holes. Perhaps it’s a shape thing, and the wires could be more straight, or more tightly twisted? My experience with these is limited, but freshly stripped, straight wire usually fits proper connectors without much fiddling. This has been true for those I’ve used personally (small 6 gage or so) as well as those I’ve observed (no idea what they use for 408V transformers for buildings, but those). I think drilling is a better solution than trimming, but can’t recommend either. Seems like some detail must be getting overlooked. Or, as stated, perhaps something like straightening or removing burrs, or maybe ease the entry (make it funnel-shaped) to help feed the wires into the hole without removing the meat of the connector…
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2/0 solid isn’t that common, but is smaller than 2/0 stranded, so that might be your issue.
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Do not drill these out. They are made of a base material and have a highly conductive plating on top of that. You would drill off the plating. This will cause a high resistance connection, generating a lot of heat, and I have seen this result in melting the connector and subsequent fire. Annoying as it may be, you need to buy the correctly sized connectors and terminal blocks.
As previously mentioned, you often have to have freshly stripped wire for it to fit into the hole. This is when the strands are at their most compact. You may have to spin the connector onto the wire, turning it in the direction of the lay of the strands so they become even more compact. You then need a hydraulic crimper to properly crimp the connector and ,again, prevent a high resistance connection. Your pictures of the lugs show the interior of the barrel is clean. They should come with a (usually) gray paste in the barrel. This is an anti-oxidation paste so the connection does not corrode and degrade over time. You can buy the paste or other form of anti-oxidant and apply it yourself. It should be used on all crimped or pressure (screw) connections.
What the heck are you powering? 250 MCM is rated for at least 170 amps (aluminum wire) or 215 amps (copper) depending on the insulation type.
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I don’t know about the application here, but in the past, I have wired up some ridiculous overkill in a travel trailer. For us, it is impossible to know what kind of power you might get handed, currents, amps, etc. I have seen no power when the office says there’s power, the ground reversed with a pole, 110 15a circuits when they advertise 50a. Once the box was already warm to the touch from the guys plugged in next door. Generally all kinds of screwed up, and you have to test things before you use them.
I can understand wanting to make sure once power is provided, no issues should come up inside my vehicle.
Are you using a high leverage cable cutter like this? If you use something that isn’t made for large gauge cable, it will cause the ends to splay and you might have trouble fitting cable that would otherwise fit. If you are using standard diagonal cutters, you will not get clean ends.
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Yes we are using the correct cable cutters and it was freshly stripped wire we have been trying to fit in the hole. I agree with everyone it is best to buy something bigger versus trying to make it work. I just called the place where I bought the junction box and they stated that is was for a certain type of 2/0 wire (of course they didn’t put this on their website). They also don’t have any of the same type of box 6 holes out (like above) that has bigger than 2/0 holes. So we are probably just going to have to buy the type of wire that is compatible with it and redo all of our battery & string hook ups. Thanks for the input everyone, it’s much appreciated!
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That really sucks to have to do it again!
But we can all sleep more soundly @ night knowing we’ve done the best we can do. Especially the folks trusting their own awesome, well done work, living the vantasy…
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