lights dim
- Thread starter GSXR600
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chris kennedy
Senior Member
- Location
- Miami Fla.
- Occupation
- 60 yr old tool twisting electrician
The NEC's minimum requirements for service and feeder sizes we bid to get jobs.
Why would the lights dim if a hair dryer is turned on, even if was based on minimum code?
I thought the NEC requires the bath receptacle to be on a dedicated circuit, definitely not with light circuits. Same for ref.
And even if it wasn't, it's only a nuisance, not a hazard as long as the wires are protected by their respective ampacity breaker.
I thought the NEC requires the bath receptacle to be on a dedicated circuit, definitely not with light circuits. Same for ref.
And even if it wasn't, it's only a nuisance, not a hazard as long as the wires are protected by their respective ampacity breaker.
- Location
- Illinois
- Occupation
- retired electrician
Actually the NEC load calculations are very conservative and result in over sized services. Just look at what we install compared to what the power company connects to our service conductors.
- Location
- Illinois
- Occupation
- retired electrician
A lot of the dip has to do with the voltage regulation of the utility transformer. The high inrush causes a brief voltage drop. Part of the drop is in the service and branch circuit conductors, but in many cases the bigger part is in the utility transformer.
Volta
Senior Member
- Location
- Columbus, Ohio
Actually, we can have that bathroom's light on the 20 amp receptacle circuit.
210.11(C)
(3) Bathroom Branch Circuits. In addition to the number
of branch circuits required by other parts of this section, at
least one 20-ampere branch circuit shall be provided to
supply bathroom receptacle outlet(s). Such circuits shall
have no other outlets.
Exception: Where the 20-ampere circuit supplies a single
bathroom, outlets for other equipment within the same
bathroom shall be permitted to be supplied in accordance
with 210.23(A)(1) and (A)(2).
Could be part of what is happening for the OP.
K8MHZ
Senior Member
- Occupation
- Electrician
POCO - 3/0 AL direct burial. EC - 3AWG THHW.
If you are talking about overhead, take a look at how much more conductors in free air can handle vs. in conduit, sheath or buried.
Since VD calcs are not a requirement, indeed, a lowball bid could be legal and still suffer from large voltage drops at the ends of long runs.
I will bet that in the OPs situation the voltage does not drop on the line side of the main. My bet is that it is dropping at the device only. Besides long conductor runs, a bad connection will do the same thing, drop voltage under a load.
K8MHZ
Senior Member
- Occupation
- Electrician
Yes, I mentioned that but really didn't stress it well enough.
That's why it's important to take measurements at different points along the path to the device.
kwired
Electron manager
- Location
- NE Nebraska
- Occupation
- EC
Problem is voltage drop will be same for same length of same type of conductor. The higher ampacity for 'in free air' has more to do with insulation temperature than how much current the conductor can actually carry.
Bare conductors in free air don't have any insulation temperature restrictions.
I have seen services with horrible voltage drop problems all because POCO refuses to install transformer closer to the service location, and they seem to think 1/0 or smaller aluminum distribution conductors have no voltage drop effects. When you are 400-500 feet from the transformer there will be voltage drop issues even when only moderately loaded, but especially when motors are starting.
maghazadeh
Senior Member
- Location
- Campbell CA
If you have multy branch circuits with 1 grounded conductor (N) feeding the loads in question. any loose, burned, or bad connection in your grounded conductor (neutral) could be the cause.
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