I am running a circuit of 5 amps 1800 feet away and calling for #2 XHHW. I know I can do the 10 foot rule at the device per 240.21(B)(1). But how can I make a #2 wire fit on a 20 amp breaker when only rated for #8 max? My thought is using a disconnect, but thoughts are limited.
#2 wire on a 20A breaker
- Thread starter sryan
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- Location
- Tennessee NEC:2017
- Occupation
- Semi-Retired Electrician
You can use a splicer/reducer to reduce the wire at the device.
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Very simple. Use a butt splice or wire connector to put a short length of #8 on the end of your #2. You should be able to do that within the breaker enclosure.
If the #2 were there for ampacity this would not be allowed or safe. But since the size is just to minimize voltage drop a short (under 100 feet!) section of smaller wire will not be an issue.
Strathead
Senior Member
- Location
- Ocala, Florida, USA
- Occupation
- Electrician/Estimator/Project Manager/Superintendent
The only way that I can think of easily is to use a polaris lug or a kerney with tape, to splice a piece of small wire right inside the panel. Nothing wrong with that. A short piece of #12 will cause almost no voltage drop difference. The tap rule doesn't apply to this situation. It is only for using a wire that has lower ampacity than the upstream breaker. Voltage drop isn't an NEC rule it is merely a fine print note.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Just splice a #12 to the #2 on each end and terminate.
Mmmmm, only 5a? 1800' of #2 wire? $$$$.
Could stepping up to 480v and back down to 120v be more cost effective?
Have you priced (2) 1ph 1kva 480-120/240 transformers and compare that to the cost of 1800' of #2 wire? Then at 480v the amperes will be 1/4 or 1-1/4ⁿ8a. The voltage drop on 1-1/4a may be better to deal with.
- Location
- Illinois
- Occupation
- retired electrician
Don't forget that the EGC will also have to be #2 for this circuit.
Carultch
Senior Member
- Location
- Massachusetts
Excellent point. Good luck terminating that. It is common for panels to have a ground bar capable of #4 thru #14, unless they expect larger ground wires, as is the case when larger branch breakers can be installed.
Are you permitted to "step down" ground wires with a splice to the smaller EGC size directly from Table 250.122, when you need to upsize them to match the upsize ratio of an upsized line conductor?
- Location
- Massachusetts
I don't see anything prohibiting stepping the EGC down but i would just add a a lug to the panel.
Carultch
Senior Member
- Location
- Massachusetts
Can you do that at a field-drilled hole?
Or factory holes that aren't indicated as grounding holes?
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Good question.
Electrically and in relation to the *reason* for that code provision the down splice should be fine.
Again it is fault current VD that is at issue rather than fault current ampacity.
But it comes down to the AHJ.
If you put in s terminal strip and transition the hot, neutral, and EGC all at the same point you have an excellent arguing point.
Carultch
Senior Member
- Location
- Massachusetts
The performance and economic issues persist either way. Either you pay for and loose energy through the wire, or you pay for and loose energy through the transformer(s). It's a tradeoff.
- Location
- Massachusetts
I might, but typically I drill a 1/4" hole, scrape off the paint and use a nut and bolt to attach an lug.
- Location
- Massachusetts
I think we may be overthinking things.
Of course you can reduce the EGC where you reduce the circuit conductor size.
I don't know about you but I can. My taps are just as good as a factory tap.
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- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Except with the wire you pay in energy loss only when running the load(s).
With a transformer you pay in idling (magnetizing) losses 24/7 whether the loads are on or not.
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
These are nice. They go up to #2. The straddler ones go even bigger.
Attachments
- Location
- Massachusetts
They are, but you really need the right one to match the grounding bar.
What do you mean? Like brand?
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