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I have 4 terminals on my appliance, L1 L1 and L2 L2. I have 2 incoming wires on a 220v circuit, 8AWG, 40 amps. Can I use a wire nut and connect each 8 AWG wire to 2 12 AWG wires and connect each 12 AWG wire to one of the terminals? In this case, each 12AWG wire would be carrying 20amps, correct?

I'm asking because these terminals are too small for 8AWG.

Edit: L1 is supposed to be bridged with L1, and L2 with L2. Also, the only place I am getting measuring any resistance between the terminals is the 2nd L1 and L2 (15MΩ and slowly climbing): https://diy.stackexchange.com/a/164011/59766

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    Can you post photos of the appliance labeling/instructions, and/or a make and model for that matter? May 30, 2019 at 2:46
  • They do make a fork connector for that .they crimp on the supply house would loan us the tool. Do not think they have it at big box stores .They might best i seen is the yellow witch takes a # 10 awg wire read box see if rated for #8,, but highly doubt it.
    – user101687
    May 30, 2019 at 6:15
  • it likely won't be 20/20, but more like 15/25, unless you take a lot of care and measurements to precisely balance the resistance.
    – dandavis
    May 30, 2019 at 18:12
  • Can you please get us those photos, or at least the make/model? Something's up here, and we can't figure out what it is from what you've given us so far May 31, 2019 at 1:54
  • @dandavis do you think it would suffice if I just used 10 AWG wire to handle up to 30 amps per branch? May 31, 2019 at 18:55

2 Answers 2

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That would depend on the design of the appliance. If the appliance is designed to be wired that way - e.g., if each pair of L1/L2 is the connection for a 3,800 W heating element - then that should be OK, and possibly even desirable.

On the other hand, if the L1s are wired together (and the L2s wired together) - like the paired screws on a typical (not GFCI) duplex receptacle, then you can't do this because all current could flow on either wire - e.g., if one of the L1s came off of its screw then all the current would flow through the remaining wire, which would overheat.

Can't say more definitively without either instructions or schematics of the appliance.

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  • There are 3 heating elements for the 9kw heater. Apparently the 2 L1s and the 2 L2s are supposed to get bridged. There are 4 output terminals from the control unit, O1 O2 O3 O4, and none of those are supposed to get bridged. May 31, 2019 at 0:50
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Absolutely not! You cannot parallel.

Even if you are in an industrial context with large diameter wire where paralleling is allowed, there are many persnickety detail requirements, and the supply side of the paralleling must be special equipment designed for paralleling. I have some, but it feeds 1000kcmil feeders, hence the need to parallel since you can't buy single wires good for 1100A.

There is one exception, and it relates to the inside of an appliance like in your case. There, you can obey the labeling and instructions that come with the equipment. In fact you are required to. Those are the basis for the UL listing, since those are the conditions UL tested it in. That will certainly address the issue, because UL would not have approved the device with instructions if it didn't.

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  • The two L1 and L2 terminals are supposed to get bridged anyway, if that helps. May 31, 2019 at 0:47
  • This isn't really paralleling since the various L1 and L2 terminals are not connected internally -- they go to different heating elements. They're wired in parallel, yes, but that's not the kind of paralleling the NEC is talking about where two or more wires are connected in parallel to the same thing on both ends.
    – Nate S.
    May 31, 2019 at 19:16
  • @NateStrickland That's likely (though it wasn't clear). However there's still an issue. The equipment needs to be UL-listed for this connection style, and the labeling and instructions are part of the UL listing, so you can't do it unless the instructions say you can. For instance the heaters might need a 20A circuit breaker to protect them, in which case splitting 40A would be a no-go. May 31, 2019 at 21:15

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