How to 3-way splice 8 gauge wire

[TS057]

First off - I'm somewhat of a rookie when it comes to electrical work and while I've done my homework I don't know all of the general rule-of-thumb guidlines that may seem obvious to some. I know 'just enough to be dangerous' as my grandfather would say!

I need to to a feed-through a box for my compressor ciruicit. I'm running 8-2 NM-B into the box which will have a 30A outlet. The wire then continues on to another box and outlet at the end of the run.

The inspector says I can't double-tap the 30A outlet that I have in the box. He says I'll need to pig-tail to the outlet. I may have to add a second double-duplex box above the outlet to house the splice and then run the pigtail to the actual outlet box due to space restrictions.

In any case I'm having trouble finding a suitable connector to do this 3-way splice w/ 8gauge wire. I can find 2-way splices all day long but nothing for a 3-way. What are my options for completing this splice?

Thanks,

Tanner

 

[rabidsquirrel]

3M B/G+ wire nut. Ideal also has one with a capacity of #6 + 2 #8s.

 

[TS057]

I found some large wire nuts @ Lowes but they only say for up to 2-6ga wires. I don't know if that would cover 3-8ga wires.

There was nothing to be found at Menards or Home Depot.

I was really hoping for something more solid like an aluminum block w/ set-screws or similar... Just can't seem to find anything like that for a 3-way.

 

[Charles (in GA)]

Electrical supply houses will have Polaris or similar splice blocks, but they are not cheap, but are the cats meow for doing this.

Indeed, you may need a separate box for the splices due to the number/size of wires and devices, you could exceed the fill of the one box with the receptacle and the wire would be difficult to work with.

Charles

 

[madosta]

If they were 6's I'd say look at split bolts and good sealing or having an electrician crimp them and seal them. You want everything protected.

Polaris connectors are nice, but I am not trying to offer any advice either way, just an option.
http://www.polarisconnectors.com/pdfs/NSi/IPL_series.pdf

 

[TS057]

Thanks guys. I ended up finding a supply house and connector as Charles suggested. They were damn expensive - I almost had to do a double take when I saw the price on the register but long-term I'll feel better about using them.

Link to supplier site

 

[pattenp]

Why are you using #8 on a 30A outlet? Is this a 30A circuit? If so, then #10 is what you should be using.

 

[TS057]

It cost me less than $10 to go from #10 to #8. This way I'll have less voltage drop and also be able to run a 40 amp circuit instead of a 30. For right now the compressor will sit in the front corner of the garage @ the end of the run. The feed-through box is upstairs in the space above the garage. Someday the compressor will be up there. Once this happens I'll have an extra 240v outlet at the front of my garage and I could switch out to a 50A plug and run my welder from that location if I ever have any welding to do out in the driveway.

 

[pattenp]

A 30A outlet cannot be placed on a 40A circuit.

 

[matt151617]

Just protect it with a 30 amp breaker. It's very unlikely you'll ever trip it anyways.

 

[Charles (in GA)]

A 30A outlet cannot be placed on a 40A circuit per NEC

Fixed it for 'ya. I did the same thing one time, "you cannot do this" and someone noted, yes you can, it just isn't code.

I agree, cannot put the 30 amp receptacle on a 40 amp circuit.

Charles

 

[pattenp]

Fixed it for 'ya. I did the same thing one time, "you cannot do this" and someone noted, yes you can, it just isn't code.

I agree, cannot put the 30 amp receptacle on a 40 amp circuit.

Charles

Oh how true... people can do anything they want.

 

[theoldwizard1]

If they were 6's I'd say look at split bolts and good sealing ...

I am not a pro ...

Last time I had to do something like this I used copper split bolts. They worked great and were inexpensive (couple of bucks back then).

The odd thing was I was told to use 3 layers of "old fashioned" friction tape (3M 1755 - cotton fabric coated with an electrical-grade rubber adhesive).

I'm not certain if that is what is recommend these days, but I know you certainly DO NOT want to use the "10 for a $1" bargain plastic tape from Harbor Freight !

 

[1500hd]

A 30A outlet cannot be placed on a 40A circuit.

Did not see where it was said he would not change 30 amp outlet when updating to 40 amp circuit.

 

[Aceman]

It cost me less than $10 to go from #10 to #8.

You sure about that? If you had used #10 on that circuit you could of used red wirenuts instead of those more expensive Polaris insulated taps you bought....

 

[LG63]

I have a similar situation and would like to use a distribution block like this Marathon block on Ebay.
Is it permissible to put two conductors under one screw?

 

[rlitman]

No.

Back to the original post though, just keep it simple, and use the right sized wire nuts. This really isn't a big deal.

 

[pattenp]

Did not see where it was said he would not change 30 amp outlet when updating to 40 amp circuit.

Here's TS057's statment... "It cost me less than $10 to go from #10 to #8. This way I'll have less voltage drop and also be able to run a 40 amp circuit instead of a 30."

I read it as he was going to make it a 40 amp circuit but was still using the 30A outlet. Only the OP knows for sure what he was going to do.

 

[TS057]

You sure about that? If you had used #10 on that circuit you could of used red wirenuts instead of those more expensive Polaris insulated taps you bought....

How true... I was just referring to the wire. At the time of purchase I had no idea what those three-way splices would cost. It's funny how things work out...

A 30A outlet cannot be placed on a 40A circuit.

If that's true I'll use a 30A breaker or put a 50A plug on my compressor. Not hard to remedy. However, how come you can use 15A outlets on 20A household outlet circuit? This is common practice.

It is my understanding that if you have a only 1 dedicated outlet on a ciruit then the amperage rating of the outlet must match that of the circuit. If you have multiple outlets per circuit as stated above you are allowed to use an outlet w/ a lower amperage rating. Does this not apply to my situation?

 

[pattenp]

NEC only allows the 15A outlet to be used on 20A circuits when more than one outlet is used. There is no code section that I know of that applies to larger than 15A outlets that allows a smaller amperage outlet to be used than the circuit amperage.

See NEC 210.21 (B) (3)


*

 

[jbberns]

Gray or Blue wirenut

 

[tp6729]

Gray or Blue wirenut

This is what I would do.

 

['04 Cummins]

I am not a pro ...

Last time I had to do something like this I used copper split bolts. They worked great and were inexpensive (couple of bucks back then).

The odd thing was I was told to use 3 layers of "old fashioned" friction tape (3M 1755 - cotton fabric coated with an electrical-grade rubber adhesive).

I'm not certain if that is what is recommend these days, but I know you certainly DO NOT want to use the "10 for a $1" bargain plastic tape from Harbor Freight !

For these you would use rubber splicing tape like 3M 130C to fill in all voids and sufficiently cover all edges to prevent poke-throughs. It should be a nice, round ball or egg shaped mass of tape. Then you would cover all of that with a high grade vinyl tape like 3M 33+ or 88.