New listening room electrical design


I'm moving to anew house in a few weeks, and trying to figure out the electrical design.
My current room was designed by Rives and I have numerous dedicated lines in it, so, I'm somewhat familiar with the topic.
The new system proposed outline:
New dedicated subpanel, exclusively for the audio components (main located in the garage, adjacent to the new room).
I have 2 speakers (Avantgarde) with powered subs
2 separate JL Fathom subs
2 mono block amps (lamm ML2)
and number of front end component, locate on stand, that going to be on the side wall
(Preamp, crossover, TT and CD player)
I'm thinking:
Two lines with 2 duplex receptacles each to power avant-garde and JL subs
Two lines with one duplex each for Lamm mono blocks
Here is my main question:
For the preamp, crossover, TT and digital I have the following options:
1.   One line with two duplexes for the analog stuff
       Another line for digital
       3 duplex recptacles on 2 separate lines
2. One line (or two) and one power distribution box with 3-4 duplex receptacle, connected to the wall receptacle
3. Two lines hardwired (no wall receptacle and no IEC and power cord in the Power distr. box) to power distribution box, separating analog from digital receptacles inside the box

What is a better approach for the front end components?
Multiple lines feeding one duplex each,
One line feeding multiple duplexes
One line feeding power distribution box?
maril555
Though I am not an electrician, I would first look at the power you can get from the utility.
I have heard from the techs at McCormack that California power is quite variable and differences during the day/night are significant.
Should this be your case, then maybe adding a power conditioner might be something you should consider.
As far as the wiring goes, and this is only my opinion, I would have a dedicated line going from the panel to your equipment. From there, I would add whatever outlets you need to run your equipment. Stereo equipment isn't that power hungry and running extra lines for analog/digital would be overkill, again in my opinion. So, a single line should suffice which would then feed all the components. (Though if you live in a Thunderstorm or highly volatile area, I would add a whole house power protector- I am sure your electrician would be more knowledgeable. If not you could look for a high end audio dealer to give you more information.
HTH Bob 
gdnrbob
 " ... I would have a dedicated line going from the panel to your equipment. From there, I would add whatever outlets you need to run your equipment. Stereo equipment isn't that power hungry and running extra lines for analog/digital would be overkill, again in my opinion. So, a single line should suffice which would then feed all the components."

This does not look like good advice. It looks like these Lamm amplifiers can draw 1000 watts each. At 120V, that more than 8 amps. I'd want to put each of these amplifiers on its own dedicated circuit.

With dedicated lines, one of the potential advantages that should especially be exploited, imo, is eliminating voltage drop. One way to do that is to de-rate the wires from the service panel to the receptacles. For example, I have 8 AWG wire on some of my 20A circuits, pigtailed in the box to the receptacle. If you have a sub panel, it's wise to de-rate that, too. This can help eliminate voltage drop by decreasing the resistance in the wire. It also has the advantage of providing a better ground connection. This can help lower the system's noise floor.

It can't possibly hurt to separate analog and digital components onto their own dedicated lines, so I've done that, too.
 
Post removed 
Thank you,
let me narrow this down
lets forget about digital for a moment, since it’s gonna be on a separate line.
if I had 6 analog components and needed 6 outlets for them, what would be the best solution?
1. 3 separate lines with 3 duplex receptacles ?
2. 1 line with 3 duplexes?
3. 1 line and power distribution box with 3 duplexes?
4. Power distribution box hard wired to one line without IEC and extra power cable?
Enter your text ...
@cleeds "It looks like these Lamm amplifiers can draw 1000 watts each. At 120V, that more than 8 amps."





That is incorrect, the ML2 are the low powered SET, not the high powered hybrids.
Power Consumption
225 Watts @ rated output @ 16 (8,4) Ohms.

I have no idea if that changes the conclusion about how to best wire. More importantly, keep the Mick Jagger mugshot photo on display in the new room! Cheers,
Spencer

Thank you Spencer
i will
Thanks sbank, I knew that figure cleeds gave was not right.
Maril, for my money, I would go with #3.
As I said a dealer may be a good person to contact for the best info.
Johnny R (audioconnection) is an a Agon member/dealer. I would trust his opinion on anything regarding Hifi.

maril555:

I am sure your new listening room is going to sound fabulous. I hope you are planning to use A/C wall outlets that bring out the best sound in your system . I am currently very happy with the Synergistic Research Black outlets. I found these outlets to be quite good.

Did you ever get an opportunity to try the Entreq Grounding system? I have not tried that approach , but I have tried the Acoustic Revive RG-24 and the Synergistic Research Grounding Block. I do think the SR Grounding Block makes a significant improvement.

I look forward to your reports on how the new room sounds.

David Pritchard

Maril: Some thoughts to consider on your narrower set of questions. If you have one line feeding multiple receptacles or receptacles plus a distribution box, you have the advantage, I think, of eliminating the different grounding potential among separate dedicated lines. I think this is the "British" style, if I can label it as such. Downside would seem to be that you are limited to what- a 20 amp line shared by multiple devices? (Leaving isolation of the digital to one side as you suggested).
You may remember, I also have the ML2 and you are right that they don’t draw a huge amount of power, but I know Vlad always harps about not using conditioning to bottleneck the current to his amps. I don’t know if a shared line (even of all analog) would be limiting.
I also have the Duos (though if I recall, you have newish ones). I wound up installing 4 dedicated lines in my room. The downside to how it was done was that all the lines were bundled together when the conduit was brought up from the basement, so when the air compressor motor for my tonearm kicks on, it affects the other lines. (This came up in another thread- I think Jea had pointed it out). So there are some best practices, not only to gauge, per CLeeds, but other aspects of how the cabling is done, from panel to room.
I’m not sure you can have a local distribution box in the room that is hardwired under applicable code, but Jea, or someone else here with real electrical knowledge and skills can address that better than me.

It’s great fun to plan a new room- i’ve been doing it mentally for several years, waiting to relocate. I guess the biggest limitation is that this stuff is "in wall" and once done, it’s a mess to re-do or add on to. Dunno if that helps....
David,
For now I have some Oyaide R1s and Furutech GTX-D Gold-plated receptacles.
After reading some posts, I got an impression, that Oyaide R1 can be "brittle and lean"?, so, I’m having my doubts about them now.
From what I’m reading about Furutech GTX-D Gold, vs. Rodium plated, I would definitely prefer Gold version to avoid some extra treble emphasis, that people ascribe to Rhodium plated one.
I’m not sure, that the new Furutech GTX- D NFC (that are only Rhodium plated) do have the same character, as the older non- NFC kind.
Many people prefer them over the older version.

Bill,
thanks for your input. I’m leaning toward two separate lines with one receptacle each, for analog and digital, and power distribution box, connected to the "analog’ line, to accommodate additional analog component
I will definitely have I separate line for each Lamm ML2 mono block, and another two separate lines for Avantgarde powered subs and JL subs.
And you probably right about power distribution box being hardwired, as NOT being code compliant.
David,
I forgot to mention, that I have some Synergistic Research Teslaplex
outlets, that I'm planning to use for subs
And I never tried Entreq, or any other grounding device, but I'm pretty sure, I'm going to try one after my room is finished
Nice problem to have 😀

I went through the same a few years ago. My advice would be to add as many seperate lines as you can be bothered with. Ideally at least a pair on each wall, well spaced to allow for future changes in equipment location. For the sources I always recommend a pair of duplexes from each line. Oyaide make lovely quad face plates to cover that duplex pair. For amps and others then duplexes are fine. I use SR Red and now black outlets but you can always swap these out to taste later.

As to isolating digital from analog I have better results using a power conditioner for all the sources and using the isolation in that, currently SR 10UEF with 12UEF on order.

Consider your source for in wall power cable. Top end would be JPS which I have used in the past but I recently used Synergistic Cryo treated Romex which is much cheaper and easier to use. 

Also consider installing an Environmental Protections EP-2775 ground filter and EP-2050 surge protector. I also installed a Torus 75A isolating power conditioner to drive the whole thing, I have used EquiTech balanced power on wall conditioners in the past as well
Power conditioning is used to solve a problem or solve a problem that one thinks they have. Power conditioning has a sonic signature just like everything else in an audio system. If you did install conditioning I would think having a way to bypass it would be desirable. 
marill555:

I know your new room is going to sound fabulous. I have used the Oyaide R1, SR Tesla Plex, PS Audio Premier, Furutech GTXD-Rhodium, and now the Synergistic Research Black outlets. The SR Tesla Plex outlets make perfect sense for the subwoofers. Once your system is up and running I do think it is worth the effort to compare your Furutech outlets to the SR Blacks. Especially since they are sold with a 30 day trial.

All the best for a satisfying system.

David Pritchard
David, how do you compare Oyaide R1 to Furutech GTX-D (Gold), and NCF?
Be absolutely sure that all lines for your audio (& video if in same room) needs are on one phase.

Best,

Jim Smith
Have been reading tons of the reviews on different AC outlets, and find reports to be quite contradictory.
Mainly, when reviewrs compare Oyaide R1 to Furutech RDX-D NCF, some say R1 are "warmer and musical" and NCF more "analytical", yet the others state exactly the opposite- R1 are "crisper with more leading edge" and NCF more "neutral".
I'm definitely trying to avoid anything, that could be perceived as "analytical, crisp, lean, having more leading edge" in my system, and now I'm lost about the choices, I need to make.
I actually ended up having a pair of each: Oyaide R1, Furutech GTX-D (gold) and Furutech GTX-D NCF (Rhodium).
I would do the following:

  • Get 2 or three isolated circuits, making sure ground was also isolated all the way to the panel, where they are tied together at the same place.
  • Get Pure Power AC regenerators
The PP Regenerators are active, and will cancel noise on either side of the outlet. That is, they will give you a pure 120 Hz input signal, and will correct for a lot of noise on the other side. They are designed by the same guy who owns Jansen Transformers. Really smart and nice guy.  They are very high efficiency and low impedance.  Parts Connexion sometimes has them on sale.

They do not however have any small units. I wish they had like a 200VA version (at 1/5th the prices) to run my DAC, BD and preamp from for instance.

Point is, they pretty much eliminate a lot of discussions and problems with outlets, wiring, blah blah.

Best,

Erik

The new system proposed outline:
New dedicated subpanel, exclusively for the audio components (main located in the garage, adjacent to the new room).


JMHO, if the subpanel will be somewhat close to the audio equipment’s branch circuit wall receptacles (15ft or less) imo, that kind of defeats the purpose of multiple dedicated branch circuits for the purpose of decoupling the power supplies of audio equipment from one another. Especially Digital from analog.

Imo, the amount decoupling is largely due the length of the branch circuit wiring impedance of the branch circuit wiring used, especially NM-B cable (Romex is a trade name of NM-B), or MC cable. (Both use THHN insulated copper conductors.)

Of course the other reason for multiple dedicated branch circuits is for fluctuating VD, Voltage Drop, that may be placed on the branch circuit from a big power amp/s playing a high dynamic music source. You don’t want the voltage fluctuating that could/would have an impact on the power amp’s power supply or power supplies of other audio equipment fed from the same branch circuit. Short runs of 20ft or less of #12awg would more than likely not be a problem. When in doubt using #10awg wire eliminates any VD fluctuations problems as the power supply of an amp draws quick gulps of current to recharge the caps in the power supply.

As always YMMV.


Thank you jea48,
Great info, as always.
However, not being an electrician, I'm having a hard time to picture having one or two lines with 6-8 outlets located in different locations?
I'm sure any electrician would know how to do it, I'm just trying to understand that for myself.
And, BTW, the subpanel in my case will be literally behind the front wall of the listening room, in the adjacent garage.
That's is the wall, where the outlets for the mono blocks are going to be.
The other two outlets will likely be on the side walls for the JL subs and powered subs in the Avantgarde speakers
And yet, another group of outlets for the front end components will be further away from the front wall.
And I would definitely go with at least 10/2 Romex.
I was actually thinking of 8/2 just for the amps.
Since we are on this topic, what specific brand and model of the subpanel would you recommend?

However, not being an electrician, I’m having a hard time to picture having one or two lines with 6-8 outlets located in different locations?


First, my intent of my previous post was not to discourage you from installing multiple dedicated circuits.

As for feeding more than one receptacle outlet from the same branch circuit it is done all the time. The feed in and feed out wires in the outlet box are jointed together and pigtailed out for connection of the duplex receptacle. As for the wire connector used to make up the joints, connections, a spring type connector should be used. Example, Scotchlok brand made by 3M or equal as used in commercial/industrial facilities. Stab in connectors used in residential dwelling units are junk!, imo.

https://www.egr.msu.edu/eceshop/Parts_Inventory/datasheets/insulated%20electrical%20spring%20wire%20...

//

I was actually thinking of 8/2 just for the amps.


#8awg? Must be some really big powerful amps. #10 is more than big enough. VD will not be a problem for your short branch circuit runs. I would be willing to bet the plug on the power cord feeding the amps is only a 15 amp plug.

//

Since we are on this topic, what specific brand and model of the subpanel would you recommend?


First, copper bus only. Stay away from a panel with Aluminum bus. The problem isn’t that the bus is aluminum it has more to do with the bus breaker tie connection made to the branch circuit breaker bus tie connector connection.

I personally like the Square D QO series. It has copper bus. Stay away from the Square D Homeline series. It has aluminum bus and I don’t care for the branch circuit breakers.

How big of a feeder was you thinking about to feed the sub panel?

For house resale I would wire the panel 120/240V. Though you will/should still have all your audio equipment that is connected together by wire ICs all fed from the same Line, Leg. All from Line 1 or all from Line 2. Not from both.

//

You need to find a good licensed electrical contractor/electrician to work with you. He will know what is required for local electrical code in your area.

Worth noting if an electrical permit is pulled there is a very good chance the branch circuit breakers in the new sub panel will have to be AFCI (ARC Fault Circuit Interrupter) type. Maximum breaker size for a 20 amp branch circuit is 20 amp, no matter if the wire is #10awg.

The electrician more than likely will have to install tamper resistant duplex receptacles for the final electrical inspection and then change them out to your audio grade duplex receptacles, after the electrical inspector signs off on the job. Ask him up front if local code for your city requires them. If yes then ask him if he will change them out after the final inspection. He may say no. He may not have any problem with changing them out providing you say you did it and not him.

Beats me why the manufactures of the audio grade receptacles are not making them tamper resistant for a residential dwelling unit application.

Jea48,
thank you again
Great info.
one more question- how would you suggest to install 2, or 3 duplexes on the same line in the same location?
Jea48
i don't know the feeder size, bu the one I have in my current home is pretty big
you can see it in my system pics
what size do you think I'd need?
And what is your opinion on twisting the wires?
Tx
jea48:

The Synergistic Research Black outlet is a TR (tamper resistant) outlet. 
I do think it does a fabulous job of improving the system's sound.

David Pritchard

one more question- how would you suggest to install 2, or 3 duplexes on the same line in the same location?


The wiring method depends on the construction of the house. Without knowing the construction of the house there is no easy answer to your question. The electrician you hire will look over the construction of the house and will determine the options of the wiring methods he will have. He then should explain the options to you.

Things to consider:

Wood stick framing? Other?

Basement? Unfinished or finished ceiling in area below the audio room?

Foundation crawl space?

House/audio room built on a concrete slab?

Above ceiling attic accessible crawl space? Other?


//


i don’t know the feeder size, bu the one I have in my current home is pretty big
you can see it in my system pics
what size do you think I’d need?

Well if you are going to spend the money to have a sub panel installed the bare minimum size in my opinion would 70 amp. Wire size #4 copper. Or bump up to #3 which is good for 85 amps.

What is the aprox total length of the feeder? Include up down and all around in the calculation. Does the garage have an accessible attic crawl space to install the feeder? If so you might want to consider NM-B sheathed cable or MC instead of conduit with loose random conductors pulled inside. Depends on the total run, length, of the conduit and installed feeder conductors.


Read pages 1 through 36.

http://centralindianaaes.files.wordpress.com/2012/09/indy-aes-2012-seminar-w-notes-v1-0.pdf

//


And what is your opinion on twisting the wires?


Twisting the wires? As in wires, conductors, that are pulled in an empty conduit? Not sure that meets NEC (National Electrical Code). Note: Dedicated branch circuits should never share the same conduit or raceway with other branch circuits. That includes multi conductor cables.

For the branch circuit wiring from the sub panel to the wall receptacle outlet boxes I would use NM-B cable, Romex. (If local code permits. And or the wiring method that must be used will meet local code for NM-B cable.) If the wiring must be in conduit ask the electrician if aluminum armor MC cable, 2 wire with ground, meets local code. Note: MC, not AC cable.

(MC comes in both solid core and strand copper conductors. Specify solid core only. Beings you will be using #10 wire the electrician will try to talk you into using stranded. He will tell you they are both rated for 30 amps. Stand your ground, Solid core only.


Example of 10-2 with ground MC cable with aluminum armor.

http://www.lowes.com/pd/250-ft-10-2-Solid-Aluminum-MC-Cable/3637694





David Pritchard said:

The Synergistic Research Black outlet is a TR (tamper resistant) outlet.
I do think it does a fabulous job of improving the system’s sound.

Thanks for the info.

Just going from memory I believe Synergistic Research has Leviton build their receptacles. Adding the TR face plate is easy to do, for a price, and thereby makes the duplex receptacle code compliant for use in a residential dwelling.

Just a guess others will follow. They are probably trying to sell off their existing inventory first. That still doesn't make it right, code compliant, though.






Jea48,
Thanks again.
The room and garage are in the above the grade basement, an concrete slab
no crawl space under the slab
Subpanel will be about 10-12 Ft. away from the main panel, and can be located on the wall, separating garage from the audio room.
The 3 walls of the audio room are sheetrock on studs over concrete
The other side wall is internal, non-bearing, sheetrock on studs, that is likely will need to be reinforced.
The ceiling is finished, with the living room, kitchen above it.
I would imagine, there is some space for the wiring.
MC vs. MC armored cable duly noted
jea48:
The new Synergistic Research Black outlets are stamped TR and one can see that TR mechanism in the outlet orifice.
The ST Tesla Plex outlets are in fact made by Levitron + modified by Synergistic Research.
The SR Black outlet has many sonic properties that I think make it worth auditioning in one's system. They are expensive and to me worth it. They are one of the few audio grade outlets sold with a 30 day return policy.

David Pritchard
I second jea48's suggestion for Square D QO line for your panel!
Solid copper buss bar, and the convenient trip window that shows a tripped breaker.  

The audio room is in the basement?

Garage floor and audio room floor are approximately on the same elevation?

Common garage wall is unfinished concrete?

All walls and ceiling of the audio room are finished drywall?

Three walls of the audio room are concrete furred out with studs? Are you sure they are studs and not 3/4" furring strips? If studs are they 2" x 4 1/2" nominal studs or possibly 2"x 2" nominal? (1 1/2" x 1 1/2")

If they are indeed 2x4s do you know if possibly they were spaced out from the concrete walls by at least 1" or 2"? Hopefully so. You can check this by removing a wall plate from a communication wall outlet, if there is one in the room. Otherwise remove the cover plate from a duplex receptacle. Take a metal close hanger and straighten it out or cut out/off the long part of the hanger to use as a depth probe. If you are lucky the communication box may be an open back wall communication bracket. Then you can physically look inside. If not make a hole against the side of wall rough in box, side opposite the stud side the box is supported to. Push the wire through the hole made in the drywall to the concrete wall behind. Mark the front of the wire probe. Measure the length.

The first 4 points are correct
im not sure about studs or furring strips over concrete
i will find that out
I always learn something from Jea. Question: unless the construction of the drywall/studs is  already first rate, won't it be way easier to tear it out and start from scratch? 
Re Jea's comment about the proximity of the subpanel to the outlets, couldn't you locate the subpanel toward the front of the garage, to increase distance to the receptacles? (I guess that means a greater distance between the main panel/service entrance and the subpanel and I don't know what code implications there are for that).
FWIW, I used some of that mass loaded vinyl (comes in rolls and man is it heavy) in my adjacent mini-room as part of a sound proofing exercise, and I gather that it is intended to give drywall construction far more mass (apart from the soundproofing application I used it for- coupled with those acoustic blankets in my case). 
I'm enjoying your research phase vicariously, and taking notes for my own benefit. 


Whart,
Why do you think I should increase distance b/w subpanel and receptacles?
Whart,
Why do you think I should increase distance b/w subpanel and receptacles?
Maril- I was curious about the solution to the comment Jea had made up thread. There, Jea said:

"JMHO, if the subpanel will be somewhat close to the audio equipment’s branch circuit wall receptacles (15ft or less) imo, that kind of defeats the purpose of multiple dedicated branch circuits for the purpose of decoupling the power supplies of audio equipment from one another. Especially Digital from analog.

Imo, the amount decoupling is largely due the length of the branch circuit wiring impedance of the branch circuit wiring used, especially NM-B cable (Romex is a trade name of NM-B), or MC cable. (Both use THHN insulated copper conductors.)"
__________
I don't know the answer, in fact, I had never realized that was an issue, so that's what prompted my question. 

I actually took it the other way- I thought the closer subpanel is to the receptacles, the less of an issue decoupling will be.

maril555,

How about an up date. What did you find out on the wall framing construction of the audio room?

I’m moving in this weekend, and not gonna know until then.
will post as soon, as I know.
in the mean time been reading on twisted L and N leads, that’s accord. To Whitlock, affords the best performance. My understanding is, that he suggests only twisting L and N, and leaving ground straight.
my question is, how you gonna do that, if all 3 are in the same jacket, as in 10/2 Romex?

my question is, how you gonna do that, if all 3 are in the same jacket, as in 10/2 Romex?

Whitlock is talking about single conductors pulled in a conduct or installed is a raceway. As I said in an earlier post twisting the hot and neutral wires together before installing them in a conduit may not meet code. Are you planning on installing conduit?

Whitlock showed the second best choice being 2 wire with ground MC armor cable followed by Romex. You can slightly twist Romex, but to much, to tight, will change the geometry of the lay of the equipment grounding conductor in relation, between, the hot and neutral conductors. Just a slight spiral twist in the entire length of the cable. Slight.....

FWIW I have to runs of 10-2 with ground NM-B, Romex, that are about 75ft each and my 2 channel system is dead quiet. Preamp and amp are tubes.

It is important to keep the individual dedicated branch circuits separated from one another as soon as possible, within reason, after they leave the electrical panel. You do not want them running parallel next to one another.



Jea,
Thanks. No, I'm not planning to use conduit, just 10/2 Romex.
Thats what I have in my current room, and it is quiet
One more question.
seems everyone suggests to keep every run from subpanel to the receptacles of equal length.
im not sure I understand how it's possible with all the outlets to be a different distance from the panel?
Won't be a problem with your short lengths. Especially beings you will be using #10 wire.
Got it,
tx
An update,
I ended up tearing down all the drywall. All walls are on 2x4 studs with 5/8" SoundBreak damped drywall to be installed.
 final configuration is as follows:
100 A Square D QO subpanel, connected to the main panel by #2 wire
EP whole house surge protector, ground filter installed.
6 separate circuits with 10/2 Solid core copper Romex
(2 for mono blocks, 2 for subs, one each for analog and digital front end equipment)
I need one more circuit for A/V processor , amp and front projector, and I’m debating making it #7, coming from subpanel, or running it from the main panel???
outlets Furutech GT X Gold and NCF, with corresponding wall plates and covers.
i also bought Furutech ET-P 609 power distributor with 3 Furutech GTX- D NCF duplexes
Maril- for my own info, what led you to the Soundbreak product? (I will eventually be doing a build out too, that's why I'm asking). 
Sounds like you are well on your way.
Exciting! 

Whart,

I contracted Nyal Mellor of "Acoustic Frontiers" to design the whole room, including construction specs, electric, etc.

Initially I was thinking of installing a second layer of drywall on a top of the old one, with Green Glue in b/w the layers, but Nyal thinks, that a single layer of 5/8' damped drywall is a better option.

So, here I am, removing the old drywall.

Actually, I'm glad I did- first, after exposing the walls and the ceiling, my contractor discovered a leak from the toilet above, two disconnected air ducts and some other small problems, previously hidden under the drywall.

Also, the electrician's job of installing dedicated lines will be much easier (and cheaper), and I can better supervise it.

Maril-Thanks re the material- yes, I suspected pulling out the old drywall would make everything easier and better. Glad you did. Let us know what you think of the sound once you get it up and running.
bill hart 
When I had my room wired I used nothing but 4x4 boxes with 2 duplex 20a outlets each(4 plugs per box) every 6' with 10ga wire and 2 to 3 circuits,you don't want to open up walls later if you change the room around.I originally seperated amps and everything else with diff circuits but have to say I mix stuff up now and can't hear a difference so I would just make sure you have plenty of outlets, Looks like the replacement for your amp draws a couple of amps(2-3) so thats not much draw, not like your running a 30a ac unit or anything and the frontend equip probably draws less.I would concentrate on good quality 20a outlets like Hubbell or the like and use the screw down connections not the push in style, they don't seem to get a good hold on the wire like the screw down style does.