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Section to section kiln receptacles/cable.


cadenrank
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Hi there! I'm new here account wise, but have been searching forums for years now. 

I have a question regarding the cable that connects between the sections of one of my older kilns. These connections use a NEMA 10-20 receptacle on the main control box, and a NEMA 10-20 plug on a cable from the sections to connect everything together (from my understanding, they were eventually switched to NEMA 6-20's), These cables are old, but still work well, and are in decent shape, but I'd eventually like to replace them. 

My question comes regarding the plug, cable, and receptacle. Are these accessories anything of specific significance? I've seen L&L sell replacement cables (this, for reference), and replacement receptacles (this one), and I've noticed that they're pretty highly priced ($42 for the plug, $48 for the cable), which makes me wonder if there's some reason they're so expensive. Do they have a higher heat rating? I'm mostly asking to know why I couldn't get a normal replacement receptacle, and a regular plug and some cable and make this myself, but since the receptacle is inside the control box, and the plug/cables hang pretty close to the kiln, I'm wondering if these need to be a special outlet (with the $42 pricetag) because of the heat. 

Thanks in advance!

Edited by cadenrank
correcting NEMA plug numbers.
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Hopefully @neilestrick will chime in, but the receptacle certainly looks like this one.  (If you look close at the pic you linked, you can see the "Leviton" name pressed into the plastic, and "Spec Grade" stamped in the metal at the bottom.  Some outlets are deeper than others (the one I linked specifically says it's a "shallow design") which might make a difference if space is really tight.

It's a little harder to tell on the cord - that also seems pretty steep for a 3ft pigtail - but can't tell what wire-size (probably 12ga, maybe 10) or type they're using.

Part of the price of the cord is the convenience of having it already 'made up' in the proper length, with connectors crimped on it ready to go.

 

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27 minutes ago, Rockhopper said:

Hopefully @neilestrick will chime in, but the receptacle certainly looks like this one.  (If you look close at the pic you linked, you can see the "Leviton" name pressed into the plastic, and "Spec Grade" stamped in the metal at the bottom.  Some outlets are deeper than others (the one I linked specifically says it's a "shallow design") which might make a difference if space is really tight.

It's a little harder to tell on the cord - that also seems pretty steep for a 3ft pigtail - but can't tell what wire-size (probably 12ga, maybe 10) or type they're using.

Part of the price of the cord is the convenience of having it already 'made up' in the proper length, with connectors crimped on it ready to go.

 

I saw that as well on the Lowe's website. And the receptacles that are in the kiln already just look like normal receptacles from the outside. I just can't fathom spending almost $200 to replace all of the cables and receptacles, unless there's good reason to (like using the consumer levitons and plugs and such would either shorten their lives, or overheat, etc.)

I believe the existing wiring on the old cord on my kiln are 12ga. 

If I knew that it was just normal cable and plugs and receptacles, I'd have no issue completing this all on my own, but again, I don't wanna put in parts and they either overheat, or don't have a lasting life because of the heat around them, etc. if there's something special about the receptacles and cable that would prevent that or something else I'm overlooking. 

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Make sure everything is rated for 20 amps. A standard outlet will work fine, but you could go with a heavy duty model if you want it to be extra durable. The reason the cables are so expensive is because they can be.:D Replacement parts are profitable for any business. Try to build a car by buying all the individual parts and it'll cost you 5 times as much as buying the complete car. Also, the cables are rated to 105C/220F, whereas the cable you can get at the hardware store is usually only rated to 90C. So they're not the cheap stuff. You can get 105C/220F cable at McMaster.com, just search SEOW cable. Kiln power cords are also rated to 105C/220F.

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Thank you guys! If I were to get the SEOW cables, would the plug on the other end (that would be plugged into the control box receptacles) also be able to just be a standard NEMA 5-20 plugs? 

Fully understand the replacement parts situation, and wasn't trying to say that the L&L replacements were too expensive, just trying to see what the difference was, if there was one. If there was a significant difference, and the cost was worth it, then I'd definitely get the parts from L&L. 

Thank you all again!

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31 minutes ago, cadenrank said:

If I were to get the SEOW cables, would the plug on the other end (that would be plugged into the control box receptacles) also be able to just be a standard NEMA 5-20 plugs? 

You should use the 6-20 setup because it's rated for 240 volts. The 5-20 is only rated for 125 volts.

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1 minute ago, neilestrick said:

You should use the 6-20 setup because it's rated for 240 volts. The 5-20 is only rated for 125 volts.

I corrected that in my original post, but didn't realize I typed it again in that response lol. I meant 6-20. 

And in reference to McMaster Carr, for those plugs and receptacles, would you think their standard for the 6-20p and 6-20r would be suitable vs. the premium? Neither of them have any temperature ratings in their specs, and one is just specified for general purpose, the other for tough, repeated use applications. 

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9 minutes ago, cadenrank said:

And in reference to McMaster Carr, for those plugs and receptacles, would you think their standard for the 6-20p and 6-20r would be suitable vs. the premium? Neither of them have any temperature ratings in their specs, and one is just specified for general purpose, the other for tough, repeated use applications. 

Yeah, they should work.

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22 hours ago, neilestrick said:

Yeah, they should work.

Just out of curiosity, from my understanding this doesn't matter, but I was just curious if you had any input on this. 

This kiln currently has 10-20 plugs and receptacles. Is NEMA 10-20 and 6-20 interchangeable? When I was looking at ordering them, the 10-20's are listed as ungrounded, and the 6-20 is listed as grounded. Maybe I just don't have a good understanding of how 3 wire 240v AC works aside from wiring it, but I would assume the 3rd blade in the 10-20's is neutral, and the 6-20's is the grounding pin. Are those interchangeable/does this make a difference? It's not a big deal to put 10-20's back into it if I'm making my own cables, but everything I see as replacement parts for these section connections are all 6-20's now is why I was assuming there was a reason for the 6-20's.  *Added: Looking back at a picture of this connection inside of the kiln, I actually see that the wire in the existing plug that would be in the 10-20's neutral pin, is actually attached to the wire that grounds to the control box as well, so I think I answered my own question, but still would like input, if you have any!

Thanks again for all of your help 

Edited by cadenrank
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@neilestrick sorry to have so many questions for you lately, but I went ahead and ordered all the parts to replace the section to section wire, plugs, and receptacles. I haven't started the project yet, but am curious about something from an electrical standpoint. 

So for the 240v 6-20 receptacles, do the hot positions matter? I obviously intend to keep them as close to the original configuration as possible, but the old existing wire from the sections has two black wires, and a green wire. Additionally the wires in the main box for the receptacles  are also all black, besides the green ground wires. The old plugs have the same color screws on them for the hot terminals, so I don't really have a way to tell for either end, if that makes sense. 

 My question is basically, on the switch, does it matter if the two hots would be reversed? Either on the receptacle end, or the sections switch end? 

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40 minutes ago, Bill Kielb said:

Worth mentioning obscure fact, if you go elsewhere in the world one of them can be 240v and the other a neutral. So they could be polarized …… outside the US.

Interesting! I know for a fact that each pole is 120v, I just didn't know if it made a difference if the receptacle had one pole, but the plug and cable was wired to a different pole somehow if it made a difference. 

Unrelated question to the last question, but relative to the original post: If the cable coming into the sections control box is SEOOW, do the wires need fiber glass or otherwise some other type of insulation around it once it splits off inside of the control box? I have some spare fiber glass sheathing that I'll probably slip onto them just to be over the top, but was just curious if it was necessary. For reference, the inside of the sections control box is pretty much just the kiln jacket, a small sheet metal heat shield, and then the switch/connections. They're pretty much fully open air flow (a grate type of ventilation) on the top and bottom of the control boxes. 

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The wire I'm using to make the connections inside of the control box is nickel coated copper with fiberglass insulation around them. Combined with high temp ring terminals, which are nickel plated steel I believe. I just noticed on the 6-20 receptacles I purchased to replace the receptacles have "CU WIRE ONLY" stamped on the back. Being that neither of these are just copper, do I need to find some other 6-20 receptacles? 

Edited by cadenrank
found out what the wire type was, but still not sure about application
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Quote

@cadenrank
do
I need to find some other 6-20 receptacles? 

They are likely both nickel plated copper which should be fine. Receptacles used to be CU/AL for compatible with copper or aluminum. Turns out aluminum was not good and receptacle makers started marking Cu  only to ensure aluminum was not used. Nickel plated stuff and brass terminals have never been an issue that I am aware of. I believe you should be fine as is.

Edited by Bill Kielb
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When I was dremeling at the ring terminals, I thought they looked like copper underneath, but I couldn't find any ring terminals online high temp that weren't listed as nickle plated steel, and the website I bought them from doesn't specify their composition. The wire is nickle plated copper, but will have the ring terminal crimped to it in this application.. And the receptacle's terminals are brass. I asked the comapany (the ceramic shop) if they knew the material of the ring terminals, but they're closed now so I won't hear until morning exactly what it is. But if nickle plated doesn't have an issue with brass, then I think either way it should be good.

Thank you for the information!!

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3 hours ago, cadenrank said:

I just noticed on the 6-20 receptacles I purchased to replace the receptacles have "CU WIRE ONLY" stamped on the back. Being that neither of these are just copper, do I need to find some other 6-20 receptacles? 

I've never had a high temp terminal be a problem in any setup.

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