Will there be voltage drop due to splices in a wire run?

[macmikeman]

For instance in a fairly long run of 3/0 that will have 2 splice cans as part of the run. Using either Polaris connectors, or Kearneys can they add to the voltage drop? Been quite a few years since I have done a long run, I cannot remember if this is a significant factor to work out before final sizing the wire for the pull.

 

[TOOL_5150]

For instance in a fairly long run of 3/0 that will have 2 splice cans as part of the run. Using either Polaris connectors, or Kearneys can they add to the voltage drop? Been quite a few years since I have done a long run, I cannot remember if this is a significant factor to work out before final sizing the wire for the pull.

I do not know of anywhere in the code that talks about splices adding to the voltage drop calculation. A good connection should have next to no voltage drop. Polaris is recomended for the best connection - IMO.

~Matt

 

[charlie b]

• Will there be voltage drop at the splice point? Yes.
• Will it be higher than you would have seen with a continuous wire? Yes.
• Will it be high enough to be of concern? No, if the splice is done properly.
• Should it be taken into account in the VD calculation? No.
• Is it a code issue? No.

 

[mxslick]

• Will there be voltage drop at the splice point? Yes.
• Will it be higher than you would have seen with a continuous wire? Yes.
• Will it be high enough to be of concern? No, if the splice is done properly.
• Should it be taken into account in the VD calculation? No.
• Is it a code issue? No.

Charlie has it right, but I would add that if the VD is on the edge of acceptable, when computed for an unbroken conductor run, you might want to think of possibly upsizing one size on the conductors (for at least the first part of the run) to compensate for the however slight drop a splice might contribute.

If this is a critical feeder or has a heavy continuous load that is. Otherwise I agree fully that a properly made splice would pose no concerns at all.

 

[LarryFine]

Charlie has it right, but I would add that if the VD is on the edge of acceptable, when computed for an unbroken conductor run, you might want to think of possibly upsizing one size on the conductors (for at least the first part of the run) to compensate for the however slight drop a splice might contribute.

If this is a critical feeder or has a heavy continuous load that is. Otherwise I agree fully that a properly made splice would pose no concerns at all.

I'd be concerned with the longevity of any splice I expected to have any discernable (read: appreciable) voltage drop.

If a splice has any more VD than its conductors, it would have more heat than the conductors. It shouldn't have either one.

Added: A feeder with critical or continuous loading should have these concerns already addressed and compensated for.

 

[480sparky]

I reccall someone did a mathetmatical method to this question, Turns out something like 14,000 splices (according to my swiss cheese memory) will create enough Vd to cause concern.

 

[ptonsparky]

Use a burndy, or similar, crimp tool with splice and the vd will be less than an equivelant length of wire.

 

[macmikeman]

Thanks gang. You have told me pretty much what I was expecting to hear, but still yet, the random thought of the splices struck me and it began to nag at me some. Couldn't remember if I read something here about it or not. Next week it gets pulled. Hi Ho

 

[ohmhead]

Well if you think about it a breaker in your panel is one of the worst for contact or a switch as far as a point of a bad connection . Take care

 

[iwire]

Charlie has it right, but I would add that if the VD is on the edge of acceptable, when computed for an unbroken conductor run, you might want to think of possibly upsizing one size on the conductors (for at least the first part of the run) to compensate for the however slight drop a splice might contribute.

If this is a critical feeder or has a heavy continuous load that is. Otherwise I agree fully that a properly made splice would pose no concerns at all.

So to sum up with what you said, if all other aspects of good design practice are entirely ignored ......... additional splices might be an issue. :grin:


Personally I hate unneeded splices but that has much more to do with my own weirdness than any real electrical issue.

 

[templdl]

Remember that voltage drop=loss= heat.
If on had a voltage drop at a splice there would be heating of some magnitude. The voltage drop for a run of cable would equate to the losses or heating distributed along the length of the cable which wouldn't be noticed.
Should one have a voltage drop at a spice which would be a resistance of some value, the loss would be concentrated at that point which equated to heating.
As such one should pay attention to the integrity of the splice as one would when terminating cables on a breaker, switch, etc.

 

[mxslick]

So to sum up with what you said, if all other aspects of good design practice are entirely ignored ......... additional splices might be an issue. :grin:


Personally I hate unneeded splices but that has much more to do with my own weirdness than any real electrical issue.

LOL another sign of the apocalypse...Bob and I agree on something again!! (The bold part) :grin:

 

[flashlight]

Remember that voltage drop=loss= heat.
If on had a voltage drop at a splice there would be heating of some magnitude. The voltage drop for a run of cable would equate to the losses or heating distributed along the length of the cable which wouldn't be noticed.
Should one have a voltage drop at a spice which would be a resistance of some value, the loss would be concentrated at that point which equated to heating.
As such one should pay attention to the integrity of the splice as one would when terminating cables on a breaker, switch, etc.

This is a nice explanation. It also explains why LV wiring can be so dangerous
if there is a bad splice resulting in VD.

(--also agree w/ Bob's post re unneeded splices.)

 

[LarryFine]

I try to make every termination, splice, or connection like it's the most important one I've ever done. I don't get complacent with connection making, I pay attention to the details. I say to myself "This one isn't going to ever become a problem."

 

[TwinCitySparky]

I try to make every termination, splice, or connection like it's the most important one I've ever done. I don't get complacent with connection making, I pay attention to the details. I say to myself "This one isn't going to ever become a problem."

Just don't let anyone hear you mumbling that Larry. :grin:



I also pride myself in making rock solid connections on everything I install.
While doing so, I usually say to myself, "I will not be rushed."

 

[Cold Fusion]

Having spent a bunch of time measuring battery interconnections, here is some perspective:

A mediocre battery connection is maybe .5 milli-ohms. At 200A that generates I^2R = P = 200^2 X .5 X 10^(-3) = 20W So if there were three of these splices in a box that would be like having a light bulb in there - it would get warm

A good connection is 1/10 of that, maybe 50 micro-ohms. At 200A, that generates 200^2 X 50 X 10^(-6) = 2W, or 6 watts for three splices. You wouldn't even notice it.

If the box contains no splices, but has a 4 foot loop of wire in it, then:
resistande of 3/0 is about .08 ohms/1000, or 80 micro-ohms/foot. Again at 200A, that generates 200^2 X 80 X 10^(-6) = 3.2W/ft. So for 3 - 4ft loops at 200A, the power is about 10W.

I've never measured the resistance of a splice, but is highly suspect 3/0 splice made up in a properly made split bolt is as good as a polaris, is maybe not as good as a butt crimp, but still better than 50 micro-ohms.

I don't even thnk you would ever see them - even after twenty years.

PS Would someone mind checking my math - I've been known to slip a decimal or two.

cf

 

[flashlight]

I try to make every termination, splice, or connection like it's the most important one I've ever done. I don't get complacent with connection making, I pay attention to the details. I say to myself "This one isn't going to ever become a problem."

A guy I used to work with told me splices can be too tight.
Outside of extreme examples, such as destroying the splicing means, is there
any truth to that ?