THHN, stranded or solid ?

[Whitworth]

As I cozy by the fireplace and plan my garage electrical....

What is better and in which situation would you choose stranded wire versus solid wire.

Running in conduit to receptacles and switches, - solid ?

Running in flexible conduit to stationary machines, - stranded ?

Can everything be done with stranded? And are there special considerations when joining stranded and solid together ?

Which is easier to push through metal conduit ? Or about the same ?

What about at the box, is stranded wire handled any differently when making connection to a breaker ?

I plan on a few machines being hard wired ( with service disconnect) is vibration an issue with solid versus stranded ?

What have you used or would you use in your shop ?


Thank you,

Gary

 

[lucky1]

Hi Gary,
I think your two options are either romex run through the walls or THHN run through PVC or metal conduit. I just ran a 40 amp sub panel to my garage. I used about 30' of left over 8-3 romex from the main panel to my garage wall. From there I put a junction box changing over to 4 wires of #8 thhn in a metal junction box. I ran the THHN through 3/4" PVC (fastened to wall) conduit to the sub panel. I plan on using appropriately sized THHN for the 3 or 4 circuits in conduit because I don't feel like cutting sheetrock and fishing wires through the walls. If I didn't have sheetrock up, I would definitely just use romex inside the walls. I believe you are also allowed to fish romex through conduit, but its harder to do than THHN. I noticed that the #8 THHN I used was stranded. I don't think it was available solid at the store I went to, or anywhere for the matter. It was still stiff, but very easy to fish through the conduit. Perhaps smaller gauge THHN comes in both. This stuff is not flexible in the sense that you can use it to make tool or appliance cords with. I think the wire you want to use to make plugs is SOOW. It's comes in 2 or 3 wire with a ground and is flexible like extension cords. Oh by the way, the individual wires in the 8-3 romex appeared to be exactly the same as the THHN...although they did not have the thhn markings.

 

[PaulyC]

Basically it comes down to personal preference. Solid wire tends to be easier to terminate while stranded wire is much easier to pull thru pipe. Some states (such as MA) have their own rules about terminating stranded wire, for example i have to some how make stranded wire a solid either by splicing it to a piece of solid wire, using a stake on, or using a soldering iron and tinning all the strands together. A tip for splicing solid to stranded wire is to leave the stranded just a little longer than the solid so the wire nut has more to grab on to as it bites in, as well as pulling on the wire nut to make sure it is securely on the splice. Personally, I like stranded wire better, but my work is all commercial and everything i do is pipe work.

 

[barnjunkie]

My neighbor recommended stranded THHN to me when I wired my shed. He worked as an industrial electrician all of his life. I took his advice, and personally I think it was the best decision due to the ease of pulling. I also think that the stranded makes the splices much more woven and secure.
I would strip the ends a little longer than solid, twist, and trim, then twist the wire nut until the wires revolved around each other a couple of times.
It should last a hundred years or so.

 

[rockwithjason]

answers in red

As I cozy by the fireplace and plan my garage electrical....

What is better and in which situation would you choose stranded wire versus solid wire.

Running in conduit to receptacles and switches, - solid ?

most building wire is solid up to 12ga. if given a choice most wireman will use stranded 10ga. if you use stranded then you have to use devices rated for stranded wire or an approved lug or other method to terminate

Running in flexible conduit to stationary machines, - stranded ?

as long as the flex is not moving all the time by design either will do

Can everything be done with stranded? And are there special considerations when joining stranded and solid together ?

yes. as long as you use approved connectors and not a hill billy method you are good

Which is easier to push through metal conduit ? Or about the same ?

solid will push thru about 10' maybe 15' depending on the bends and how much vertical rise there is in the conduit. stranded will only push a few feet in most cases

What about at the box, is stranded wire handled any differently when making connection to a breaker ?

no. what is important is that the equipment is listed for stranded wire and most all panel equipment is

I plan on a few machines being hard wired ( with service disconnect) is vibration an issue with solid versus stranded ?

only in extream cases

What have you used or would you use in your shop ?

solid up to 10 ga


Thank you,

Gary

 

[toplessHO]

I would use stranded to hook up anything that has vibration.
I like using solid to terminate devices such as switches or outlets.
I also find its easier to make the boxes or panels organized.
as for the comment on stranded wire and wirenuts its better not to twist them
before putting wirenut on.OTOH solid is better to twist but a proper installation of the wirenut
will twist the wires anyway.

 

[Whitworth]

I believe I saw as small as 14 gauge in both solid and stranded THHN at the box store, but that's not relevant as I wouldn't be using 14 gauge.

I plan on using 12 and 10 gauge THHN for wiring 3 circuits for receptacles and also dedicated circuits for certain tools/machines.

I'm going to use conduit and surface mounted boxes/fixtures.
I feel Romex in the walls is a lot of work, interferes with the insulation envelope of the garage and is not as flexible. For instance I may want to add task lighting in the future. With conduit I can simply extend a circuit up to the ceiling and hook up track lighting.

The conduit may run about 8 feet between duplex or quads or junction boxes for direct hard wiring.

So I am primarily concerned about ease of pulling THHN as well as what constitutes proper connections particularly with stranded wires.

Cost is about the same, stranded was a little more.

And, as mentioned I was concerned with machine vibration and use with solid THHN in flexy conduit. I'd use flexible for hooking up machines with about 3 feet length, approximately.

In the instance of connecting stranded to a machine switch/starter I was planning on using crimp on connectors.

Plans are subject to change.

Thanks everyone for the input.

Gary

 

[n8n]

If you run stranded you will have to use devices with the little clamps under the screws.

 

[teamextreme]

#12 solid
#10 and larger stranded
Stranded biggest advantage is ease of pulling, but for your 8 foot runs of probably mostly straight pipe will be no issue at all getting either wire through. Solid is much easier to handle recep and switch terminations. I would use solid for everything except #10 and above.

Just to clarify rockwithjason's comment regarding "pushing" wire. He said pushing solid was easier, which is true but be careful because he is being literal with push vs pull. Pulling stranded is easier. Pushing solid is easier.

 

[Charles (in GA)]

Use receptacles and switches that are commercial grade and backwired with a screw and internal clamp to capture the wire. No wrapping wire around screws and stranded works as good as solid. I AM NOT referring to the cheap push in backwire.......... I am referring to a type that you loosen the screw, insert the wire, and tighten the screw. It pinches on the wire with a serrated plate inside and it pretty foolproof.

I prefer solid for ease of termination, but only with 12 and 14. Both as solid are fairly easy to pull actually. I pulled a bunch of it, all by myself and didn't have any real issues.

Charles

 

[MushCreek]

Don't ever use a cheap back-stab device, especially in a building that may have more variation in temperature and humidity. Our old house in FL was wired with back-stab devices, and we always had buzzing crackling devices due to poor contact. Each time one would act up, I'd replace it with a proper device. FWIW- I saved a huge amount of money buying devices for our new house on-line. The big box stores are very expensive, especially for GFIC and tamper-resistant outlets.

 

[theoldwizard1]

Use receptacles and switches that are commercial grade and backwired with a screw and internal clamp to capture the wire .... I am referring to a type that you loosen the screw, insert the wire, and tighten the screw. It pinches on the wire with a serrated plate inside and it pretty foolproof.

Kind of pricey compared to those cheap push-in, but they are worth it !

I prefer solid for ease of termination, but only with 12 and 14. Both as solid are fairly easy to pull actually. I pulled a bunch of it, all by myself and didn't have any real issues.

Any cost difference between a 250' spool of #12 solid versus stranded THHN ?

 

[n8n]

Kind of pricey compared to those cheap push-in, but they are worth it !

Only contractors bidding to the lowest common denominator and complete hacks ever use the latter. I *always* use spec grade even if I'm doing residential with solid 14. Just solves so many problems and makes for a more durable and reliable installation.


Sent from my XT897 using Tapatalk

 

[sberry]

I have used cheap recepts for decades, cant even remember changing one out due to failure, some of mine have 1000's of cycles on them. Have a couple used in hi current but most garage generals don't really see much use.

 

[Whitworth]

Any cost difference between a 250' spool of #12 solid versus stranded THHN ?

I recall for 500 ft spool about $5 difference between the two.

 

[teamextreme]

Only contractors bidding to the lowest common denominator and complete hacks ever use the latter.

As much as everyone likes to hate on back wiring (including myself, I never use backwires), or using the cheap receps (that's all I ever use), fact of the matter is that 99% of any houses built in the last 30 years are built this way. And they work fine 99% of the time, but they do cause problems from time to time. That's a lot of hacks.

 

[Whitworth]

Going off at a bit of a tangent, I'm curious whether you guys have strong opinions of pig-tailing or not?

Positives:
Won't lose power down stream if receptacle or switch fails.
Install/repair of receptacle easier ?
Looks more professional.

Negatives:
Takes up more space in box.
Adds yet one more electrical connection that might fail.
A little more effort up front when completing finish electric.

Am I missing anything ?

 

[n8n]

As much as everyone likes to hate on back wiring (including myself, I never use backwires), or using the cheap receps (that's all I ever use), fact of the matter is that 99% of any houses built in the last 30 years are built this way. And they work fine 99% of the time, but they do cause problems from time to time. That's a lot of hacks.

Maybe I and my friends just all buy/rent/otherwise live in older houses than the rest of you all, but I've done complete device replacements on several due to starting with "hey, this recep doesn't hold a plug anymore" and then just doing the whole house in disgust after discovering an issue with more than 50% of the devices. Sometimes it's not grabbing a plug; sometimes it's pulling a device out of the wall to just proactively replace it and finding that one or more of the backstabs is only putting the lightest of pressure on the wire and it pulls right out.

 

[egdede]

Going off at a bit of a tangent, I'm curious whether you guys have strong opinions of pig-tailing or not?

Positives:
Won't lose power down stream if receptacle or switch fails.
Install/repair of receptacle easier ?
Looks more professional.

Negatives:
Takes up more space in box.
Adds yet one more electrical connection that might fail.
A little more effort up front when completing finish electric.

Am I missing anything ?

In a multiwire branch circuit: can prevent 230 volts downstream if a receptacle or switch fails (or is disconnected incorrectly).

 

[alfredeneuman]

In a multiwire branch circuit: can prevent 230 volts downstream if a receptacle or switch fails (or is disconnected incorrectly).

On a MBC, the neutral is required to be pigtailed by Code just to prevent this.

300.13 Mechanical and Electrical Continuity — Conductors.
(B) Device Removal. In multiwire branch circuits, the
continuity of a grounded conductor shall not depend on
device connections such as lampholders, receptacles, and
so forth, where the removal of such devices would interrupt
the continuity

 

[toplessHO]

In a multiwire branch circuit: can prevent 230 volts downstream if a receptacle or switch fails (or is disconnected incorrectly).

and is required by code