Strand copper wire.

Did an inspection a while back, and much of the wiring looked as if it had been replaced.

My question is this. The wiring for the 15 and 20 amp circuits was all copper stranded wiring, instead of the solid copper I usually see. I assumed at the time it was fine, but for some reason, this came back to me and caused me to question. It stranded copper okay for lower amperage circuits?

was it the appropriate size and in conduit Mark ???

Yea, it looked like the correct gage.

if it is the correct gauge and in protected conduit my understanding is it’s fine…sure one of the sparky’s will have a better explanation

Hi Mark,

if the conductors were in a conduit then its likely that they used stranded copper wire of the correct gauge as it is much easier to pull through than single strand.

Regards

Gerry

Like everyone said, if this was a conduit job, stranded is fine. Some people like to work with stranded better when pulling in conduit.

If this was cable, stranded would be a red flag. There were only a couple very special cables ever manufactured for general building wiring that featured stranded conductors. Normally, when you see a stranded cable connected in a panel, that’s normally your clue that someone improperly did some wiring with rubber cord or something like that.

If properly installed, the stranded is fine. I would check the devices, ie…receptacles and switches and make sure they used the right type and didn’t try to stab stranded wire into the back or put stranded wire under a screw connector. I’ve seen that a lot. The devices have to be “listed” for stranded wire.

Ms Sparky
http://mssparky.com/

What’s wrong with a screw connector?

Jeff

I didn’t pull any outlet covers (never do) to check the receptacles and switches. The wires were run through conduits, so from what I’m reading, I’m thinking that this was just fine. Just out of curiosity though, if back stabbing, and under a screw connector isn’t correct, then what is? There was nothing different in the service panel, lugged like you always see it.

There are “backwired” receptacles which agree with stranded wires much better. They have a hole, like backstabbed, but the conductor gets trapped between two plates inside when you tighten the screw on the side.

Most every screw terminal receptacle nowadays is okay’d for use with stranded conductors, however, but it’s not that easy to do. It would be very unusual to find a screw terminal that said “solid wire only”.

Mark you are right. It took a little bit to convince me, but you are. I’m glad you caught that. I must be spending too much time at the Nukes. Different standards. I still don’t recommend it for “side-wire (binding screw)”. But it’s not illegal.

Here’s the UL White Book page that describes it.

TERMINALS

Terminals of 15 and 20 A receptacles not marked “CO/ALR” are for use with copper and copper-clad aluminum conductors only. Terminals marked “CO/ALR” are for use with aluminum, copper and copper-clad aluminum conductors.
Terminals of receptacles rated 30 A and above not marked “AL-CU” are for use with copper conductors only. Terminals of receptacles rated 30 A and above marked “AL-CU” are for use with aluminum, copper and copper-clad aluminum conductors.
Terminals marked “75 C” may be wired using the ampacities for conductors rated 75°C as well as conductors rated 60°C in Table 310.16 of the NEC.
Terminals of the wire-binding screw, setscrew, or screw-actuated back wired clamping types are suitable for use with both solid and stranded building wires.
Screwless terminal connectors of the conductor push-in type (also known as “push-in-terminals”) are restricted to 15 A branch circuits and are for connection with 14 AWG solid copper wire only. They are not intended for use with aluminum or copper-clad aluminum wire, 14 AWG stranded copper wire, or 12 AWG solid or stranded copper wire.
Single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have been investigated to feed branch-circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:

  • Back wire (screw actuated clamp type) terminations with multiple wire access holes used concurrently to terminate more than one conductor
  • Side wire (binding screw) terminals used concurrently with their respective push-in (screwless) terminations to terminate more than one conductor

Single and duplex receptacles rated 15 and 20 A that are provided with more than one set of terminals for the connection of line and neutral conductors have not been investigated to feed branch-circuit conductors connected to other outlets on a multi-outlet branch circuit, as follows:

  • Side wire (binding screw) terminal with its associated back wire (screw actuated clamp type) terminal
  • Multiple conductors under a single binding screw
  • Multiple conductors in a single back wire hole

Duplex receptacles rated 15 and 20 A that are provided with break off tabs may have those tabs removed so that the two receptacles may be wired in a multi-wire branch circuit.

Ms Sparky