Proper wiring of general use receptacles

[don_resqcapt19]

Dreamed up, hmmm; OK. Undersized wires cause fires.


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14 AWG copper would have to be operated at 34 amps to reach a temperature of 300°C, and that is below the auto ignition temperature of almost all building materials. The voltage drop does not increase the temperature of the wire. That is based only on current.

 

[don_resqcapt19]

I would think it would be upon actual voltage, but I am not certain—though I will find out at some point.

I have my own issue with the POCO and the increased voltages. It is causing nuisance trips when it spikes up to 127V. I have a customer with this issue. They have a generator as well, which is regulated at 120V, and when it transfers; there is not an issue—It IS POCO related; I just have to prove it.


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Is that on an AFCI? Some AFCIs have internal over voltage protection to protect the electronics, but I thought that setting was closer to 150 volts.

 

[don_resqcapt19]

Sir, I did not state that the power company regulates that voltage. All circuit breakers are rated at a particular voltage and tolerance. I know for certain, that Square D is rated at 120v. This is the tolerance of the breaker, and that is the voltage we must work within. I am not certain, but believe the other manufacturers fall within the same spec.


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Yet 7.1.2.14 of UL 489 permits the circuit breaker calibration tests to be made at any voltage and either AC or DC. The tripping is only a function of the heat produced by the current across the sensing element of the breaker and the voltage plays no part in that.

 

[jap]

Dreamed up, hmmm; OK. Undersized wires cause fires.


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To the contrary, oversized wires cause fires also.

Especially if you go to put a larger size wire under a lug or terminal smaller than what it is rated for, or, make additional unnecessary splices to reduce the size of the conductor prior to terminating it.

Jap>

 

[bsmale]

Would you mind sharing the email from Square D in this forum?

Yes, it’s in pieces, so let me organize it before I post. Getting the information out of the engineer was difficult.


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[hbiss]

Getting the information out of the engineer was difficult.

Try getting them to explain why AFCIs are useless.

-Hal

 

[Seven-Delta-FortyOne]

Still, as was asked before, how do you figure VD at the end of a branch circuit, is going to affect voltage at the breaker, the beginning of the branch circuit?

 

[Strathead]

How is it worded? Does it actually say that on a receptacle circuit you must go to the last receptacle on the circuit and calculate a full load at that device?

I actually thought is broke them down to 2% 3% but you made me look. Here is the code:

C405.5.3 Voltage drop.​

The conductors for feeders and branch circuits combined shall be sized for a maximum of 5 percent voltage drop total.

 

[LarryFine]

I actually thought is broke them down to 2% 3% but you made me look. Here is the code:

C405.5.3 Voltage drop.​

The conductors for feeders and branch circuits combined shall be sized for a maximum of 5 percent voltage drop total.

So, the sizing must be based on it, but you need not actually achieve it?

In that case, the POCO is effectively off the hook, no compliance needed.

 

[infinity]

I actually thought is broke them down to 2% 3% but you made me look. Here is the code:

C405.5.3 Voltage drop.​

The conductors for feeders and branch circuits combined shall be sized for a maximum of 5 percent voltage drop total.

That seems pretty meaningless for multi-receptacle circuits. For something like a fire pump we can easily calculate the VD and compensate accordingly but how do you do that for a branch circuit with receptacles?

 

[retirede]

That seems pretty meaningless for multi-receptacle circuits. For something like a fire pump we can easily calculate the VD and compensate accordingly but how do you do that for a branch circuit with receptacles?

Agreed. Without specifying what load to use, it’s meaningless and thus unenforceable.

 

[Deetz]

Sorry for jumping in on this so late. In the Industrial field, older machines and appliances had a +/- 5% voltage variant for them to work. Nowadays I run into a +/- 10% variant. I assume most newer appliances probably have that characteristic also.

 

[n1ist]

Everything I have designed has been +/- 10%, whether appliances or lighting controls (though those had to work from 100V-10% for Japan to 347V+10% for Canada). It was easier than dealing with customer calls when using them on marginal circuits.

 

[newservice]

I have never met a POCO that guarantees a line voltage. What they do guarantee is they deliver it at 60Hz.
The listed voltages they deliver are Nominal voltages.
Square D also lists their equipment for nominal voltages.
The NEC specifies the 3% drop on branch circuits (5% overall from the service point) for “ optimal” utilization.
Hope this help.

 

[newservice]

I was not saying that I stand alone; like I said, there are few of us that design above the Code. And I do appreciate the suggestion that Don gave, and probably will start this process that way.


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There have been many discussions on this forum about ‘designing above code’ or ‘ better than the code’ or so forth. The consensus has always been to stick to the code.

 

[retirede]

I have never met a POCO that guarantees a line voltage. What they do guarantee is they deliver it at 60Hz.
The listed voltages they deliver are Nominal voltages.
Square D also lists their equipment for nominal voltages.
The NEC specifies the 3% drop on branch circuits (5% overall from the service point) for “ optimal” utilization.
Hope this help.

They don’t guarantee voltage, but they are supposed to be bound by ANSI C84.1, which limits variation to +-5% under normal conditions.

 

[don_resqcapt19]

They don’t guarantee voltage, but they are supposed to be bound by ANSI C84.1, which limits variation to +-5% under normal conditions.

In Illinois the voltage limit for utilities is set by the Illinois Commerce Commission, and set at ±10% for voltages other than 120 volts.

Illinois Commerce Commission JCAR rules
Section 410.300 Voltage Regulation
a) Standard voltage. Each entity supplying electrical energy for general use shall adopt a standard service voltage of 120 volts (when measured phase to neutral) and shall maintain the service voltage within the allowable variations from that value at all times.

b) Allowable voltage variations. For service rendered at the standard service voltage, voltage variations as measured at any customer's point of delivery shall not exceed a maximum of 127 volts nor fall below a minimum of 113 volts for periods longer than two minutes in each instance. For service rendered at voltages other than the standard voltage value, voltage variations as measured at any customer's point of delivery shall not exceed 10% above or below the service voltage for a longer period than two minutes in each instance.

c) Variations of voltage in excess of those specified above shall not be considered a violation of this Section if caused:
1) by operations of a retail customer in violation of an agreement with or the rules of the entity;
2) by the operation of apparatus on a retail customer's premises that results in large inrush currents;
3) by infrequent and unavoidable fluctuations of short duration due to system operation; or
4) by acts of nature or other situations beyond the entity's control.

 

[retirede]

In Illinois the voltage limit for utilities is set by the Illinois Commerce Commission, and set at ±10% for voltages other than 120 volts.

I wonder how that came about?

 

[don_resqcapt19]

I wonder how that came about?

No idea, that wording has been the same for a very long time.

 

[gene6]

I actually thought is broke them down to 2% 3% but you made me look. Here is the code:

C405.5.3 Voltage drop.​

The conductors for feeders and branch circuits combined shall be sized for a maximum of 5 percent voltage drop total.

Back in the dawn of time when I was learning the trade I **think** voltage drop *was* in the NEC? Then it was removed but NYC kept it in the NYC code.
Now it seems most states have adopted a energy code that covers electrical work, like lighting and motor efficiency so no reason to add voltage drop back to the NEC as its already in the energy code.
I have never seen voltage drop enforced on a residential general purpose circuit.
When I have failed inspections over voltage drop was a piece of equipment in a industrial building, and it was the EE's fault as they provided the design 'to meet all codes'.
If you self design your jobs then you will run into the energy code stuff, so its important to teach that there are other codes we need to be familiar with, such as fire and life safety codes ADA accessibility etc.