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MEXANDME
06-18-2009, 09:40 PM
A client gave the construction foreman the "cans" for the LV step lights so he could form them up for the steps concrete pour. So, he forms them up but the electrician runs UF cable to the first can and then loops it to the next three cans thinking they are line voltage lights. They then pour the steps. Eventhough the UF cable is in flexible conduit, there is some risk in trying to pull out the UF and pull LV cable back in.

Any problem with me using the UF cable for the LV step lights? It is 12 gauge UF cable.

Thanks,

Mex

Lite4
06-18-2009, 09:46 PM
You will be ok if using a multi-volt transformer. The stranded LV cable works better for LV because there is more surface area for the current to travel on with all the individual wire strands and it is also more flexible than the UF solid wire so the connections can be tighter which is very important on the LV side. You will be ok though, just record and adjust your voltage accordingly as needed like normal.

irrig8r
06-18-2009, 11:44 PM
You will be ok if using a multi-volt transformer. The stranded LV cable works better for LV because there is more surface area for the current to travel on with all the individual wire strands and it is also more flexible than the UF solid wire so the connections can be tighter which is very important on the LV side. You will be ok though, just record and adjust your voltage accordingly as needed like normal.

I've heard several times now that what you say there about surface area is just a widespread myth and that the only reason we use stranded cable is that it lays down in the trench better/ is more flexible.

Lite4
06-19-2009, 08:55 AM
I've heard several times now that what you say there about surface area is just a widespread myth and that the only reason we use stranded cable is that it lays down in the trench better/ is more flexible.

Possibly, it could be an urban legend among lighting geeks. Just what I have been told, but it makes sense to me. The flexibility issue is a no brainer though.

worx
06-19-2009, 09:26 AM
I have heard the same thing, I think it is referred to as the "skin effect". Current travels across the "skin" of the copper and with stranded cable you have more "skin" surface.

Of course, it could all be urban legend.

But lets not confuse "skin effect" with Sasquatch......

irrig8r
06-19-2009, 12:11 PM
Of course, it could all be urban legend.

But lets not confuse "skin effect" with Sasquatch......

http://www.zubeworld.com/crumbmuseum/bigfoot.jpg

drewguy
06-19-2009, 10:10 PM
Possibly, it could be an urban legend among lighting geeks. Just what I have been told, but it makes sense to me. The flexibility issue is a no brainer though.

So stranded cable rated 12A actually is different from solid cable rated 12A? :rolleyes:

The flexibility isn't an issue if the cable is already in.

Lite4
06-19-2009, 11:26 PM
No not really. The resistence of stranded 12 AWG cable is .00162 per foot and solid 12 AWG is .00159 per foot. Nearly identical, the flexibility of the stranded cable is just easier to work with when burying. If there is wire already in the wall just say thank you and wire it up.

David Gretzmier
06-19-2009, 11:41 PM
you can use solid. we have to use it here when running inside the home. watch your amps. 12 guage solid can get hot.