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I have a question regarding Polaris type electrical connectors. I should state right up front I am NOT an electrician, but have done some home wiring and think I know most of the basics.

I am trying to tap into an electrical circuit that is a 8 gauge cable (Type NM-B) (40 amp circuit). I have read about the Polaris type connectors and think this looks like the easiest way to go. The problem I am having is determining what size Polaris connector I need to use. The terminology they use doesn't make sense to me. I am looking at one sight that sells these connectors and (for example) the wire size says "500 MCM - 4 AWG" or another says "1/0 - 14 AWG", those terms don't mean a lot to me so I am not sure what to look for. I can't seem to find any of these type connectors for an 8 gauge cable. I hope that I am making sense, and thanks in advance for any help you can offer.

New Info: So I have read some of the comments below and will try to add some more information on what I am trying to do, I apologize if I am not doing a good job at describing this, I find it hard to put into words what I am trying to do. The 40 amp circuit is for a radial arm saw that is located in my work shop. The 8 gauge cable runs from the circuit breaker box to the shop and ends with a dryer type outlet (sorry I don't know the proper technical term for that). I want to add another outlet of the same type between the existing outlet and the breaker panel for another machine. I want to cut the existing cable and add a box (4" x 4" x 2") at each of those cut ends (2 boxes total). At each of those boxes then "splice" (again that is probably the wrong term - sorry) a new length of the 8 gauge cable to go to the new outlet. Those 2 new cables would then be connected together at the new outlet. I think I would just use wire nuts to make the connections at the boxes, so wouldn't need to go with the Polaris connectors. I have tested making those connections with just some scrap pieces of the 8 gauge and an appropriate sized wire nut and I was able to get a good strong connection that way. I hope this makes more sense. Thanks for your help.

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    Did you say "tap"? Sorry to ask, but when novices say "tap into" and "8 gauge" in the same sentence, I fear that they're about to do something they'll regret, and that further advice is warranted. Could you ask a new question describing your project in full and asking about the best way to do it? – Harper - Reinstate Monica Mar 29 at 23:23
  • Yes, please tell us what you are trying to do. It sounds like a bad idea already, and it's clear you have no idea what you are doing. This combination of facts makes for a giant red flag. – J... Mar 30 at 14:49
  • The dash in "1/0 - 14 AWG" means "to", I believe. Its stating a range of sizes that are compatible. – UuDdLrLrSs Mar 30 at 16:35
  • Yeah, something is wrong here. Radial arm saws don't plug into "dryer type" outlets, nor do they require 40A of current. Either you have a monstrous saw OR it has been modified somehow to fit your broken outlet scheme. Large appliances or tools that need that much power must have dedicated circuits - one tool, one circuit, one breaker. Everything about this plan sounds wrong and unsafe. What you most likely need to do is install a subpanel in your shop. Suggest you consult a real electrician before you get even deeper into trouble. – J... Apr 1 at 12:30
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Your wire is #8 AWG, copper since it's a 40 amp circuit. So you need a connector that will fit that wire. The sizing on the connectors states what wires will fit in the individual holes in the connector. So in your question you have a connector that is rated for "1/0 - 14 AWG", it will handle a 14 AWG to a 1/0 AWG wire. Since your wire is a 8AWG, this connector would work. A sample wire chart is shown below.

enter image description here

Since these are expensive connectors, you want to get the smallest one that will accommodate the wire sizes you are using. There are other connectors available so you might want to ask another question about this and explain what you're connecting and you might get some better ideas.

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    In the example diagram, is "1/0" the one labelled 1 AWG or the one labelled 0 AWG? – user1686 Mar 29 at 22:22
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    @user1686 Sorry, my bad. The one labeled "0" is the "1/0" and would be called "one ought" , 2/0 called "two ought". – JACK Mar 29 at 22:28
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Electrically speaking, such a connector is fine

Mechanical setscrew (Polaris™) connectors are what is called range taking, which means they can accept any wire size within their specified range. So, your 14-1/0 connectors will work, technically speaking, for 8AWG wire.

However, I probably wouldn't do that this way

The issue, however, is that this style of connector is very bulky compared to a wirenut, bulky enough that you likely won't be able to cram them into a standard junction box. They're generally used for wires 4AWG and larger that must be spliced within NEMA-standard pull boxes, which are much larger and more spacious than junction boxes (the smallest pull box is a 4"x4"x3", comparable in size to a large 4-square junction box, and they simply go up from there to pull boxes the size of your breaker box, used for splicing very large wires).

Most push-in splices can't handle 8AWG, either, so you're left with wire nuts if you want this to fit in a standard junction box; you'll need the largest size available for this splicing job, and you'll need to make sure to crank them down tight (if your wirenut job can't pass a good, solid pull test, it needs to be redone).

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    Sounds like a good application for that Mac Block connector you mentioned earlier. When I hear a novice say "Tap", I get very concerned about exactly what's up... – Harper - Reinstate Monica Mar 29 at 23:20
  • i get nervous when I see DIY wire nuts over #10 wire sizes. I don’t believe I have ever seen them properly twisted with 3 wires and rarely with 2 wires. And yes I have repaired more than a couple that were not properly installed usually 1 wire burned off from a bad connection. – Ed Beal Mar 30 at 14:50
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Each connector covers a range of sizes, the size ranges overlap to allow joints between wires of different sizes.

A complication is that Americans use different systems to measure different sizes of wire.

Normal domestic wire sizes in north america are measured in AWG, with a larger number meaning a smaller wire. Roughly speaking the wire cross sectional area (CSA) halves with every increase of 3 in the AWG number. In the context of american mains wiring if someone says "gauge" they mean AWG.

However for wires larger than 0 AWG they move to different systems. For moderately big wires they extend the AWG system with increasing length sequences of zeros representing increasing sizes. Sometimes instead of writing out the sequence of zeros they put a number followed by a slash and then a zero. So "1/0 AWG" is the same as "0 AWG", "2/0 AWG" is the same as "00 AWG" and so on.

For really big wires they give up on the AWG system and just measure the overall CSA of the wire in thousands of circular mils (MCM).

So lets convert all the sizes mentioned in your question to cross-sectional areas and put them in order.

  • 500 MCM ≈ 253 mm²
  • 1/0 AWG = 0 AWG ≈ 106 MCM ≈ 53.5 mm²
  • 4 AWG ≈ 41.7 MCM ≈ 21.2 mm²
  • 8 AWG ≈ 16.5 MCM ≈ 8.37 mm²
  • 14 AWG ≈ 4.11 MCM ≈ 2.08 mm²

So the "500 MCM - 4 AWG" connector is too big, the smallest wire it is rated to support is 4AWG which is too large for your 8 AWG wire.

8 AWG is between 1/0 AWG and 14 AWG, so the "1/0 - 14 AWG" connector would work, it's likely unnecessarily bulky though. Doing some searching it seems that there is also a "4-14 AWG" version which would cover your needs while being less bulky

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The "1/0 - 14 AWG" is the proper size for the small connections you are trying to make, for wire approximately 3/8 to 1/16" diameter. The other are larger, for up about 3/4" diameter wire.

Wire size #8 is between #14 and #0 (called 1/0 for some strange reason).

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The 1/0 or 0 it sounds like “ought” 1/0 to 14 is the size you want that is a wire size range, I love these connectors quick and pre insulated. If you have aluminum make sure you get the ones rated for aluminum some are some are not. Those will normally say al/cu and some times have a x or digit prior to the al . 14, 12, 10, 8, 6, 4, 2, 0, 00, 000 , 0000 The last 4 are also 1/0, 2/0, 3/0, 4/0 Or a hyphen instead of a slash but the connector you found will work through that range. Your range is 14-1/0 so it will work not the 500 mcm that is 4/0 and the next few sizes larger.

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