400 amp service(320) voltage drop
- Thread starter Trouyano
- Start date
- Status
- Location
- Massachusetts
Assuming a single 400 amp OCPD It is not even enough for 400 amps if it was just 10' away.
Last edited:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Not even close. CU, yes.
- Location
- Massachusetts
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
It's closer than I thought once I looked it up in the table for dwelling units.hmy:
Oops, I forgot the resi table.:slaphead:
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Okay, resi table says 500 AL kcmil is good for 350A and 350A is a listed standard sized breaker, so no.
240.6 Standard Ampere Ratings.
(A) Fuses and Fixed-Trip Circuit Breakers. The standard
ampere ratings for fuses and inverse time circuit
breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50,
60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300,
350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000,
2500, 3000, 4000, 5000, and 6000 amperes. Additional
standard ampere ratings for fuses shall be 1, 3, 6, 10, and
601. The use of fuses and inverse time circuit breakers with
nonstandard ampere ratings shall be permitted.
240.6 Standard Ampere Ratings.
(A) Fuses and Fixed-Trip Circuit Breakers. The standard
ampere ratings for fuses and inverse time circuit
breakers shall be considered 15, 20, 25, 30, 35, 40, 45, 50,
60, 70, 80, 90, 100, 110, 125, 150, 175, 200, 225, 250, 300,
350, 400, 450, 500, 600, 700, 800, 1000, 1200, 1600, 2000,
2500, 3000, 4000, 5000, and 6000 amperes. Additional
standard ampere ratings for fuses shall be 1, 3, 6, 10, and
601. The use of fuses and inverse time circuit breakers with
nonstandard ampere ratings shall be permitted.
- Location
- Massachusetts
Unless he has more than one main.
Two 200 amp main breaker panels with a total calculated load under 350 and he is good to go.
Two 200 amp main breaker panels with a total calculated load under 350 and he is good to go.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
ptonsparky
Tom
- Occupation
- EC - retired
What will your load be? Most likely not 320.
- Location
- Massachusetts
It does not matter what they call it in PA, if you have a single 400 amp main breaker it is an NEC violation to use 500 AL.
That is entirely dependent on the load, as ptonsparky pointed out it is unlikely your calculated load is 320 amps.
What is your calculated load? If you do not have that you really cannot do a voltage drop calculation.
ptonsparky
Tom
- Occupation
- EC - retired
There is no set distance for increasing the conductor size for VD. You have to calculate it with the parameters you or the customer are willing to accept. 5% may be fine, maybe not.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
A 400 amp meter base is rated 400 amps for non continuous loads but only 320 for continuous loads. A 200 amp meter base is rated the same way. 200 amps for noncontinuous loads but 160 for continuous loads.
- Location
- Chapel Hill, NC
- Occupation
- Retired Electrical Contractor
Again it depends on the load. If you want to use the 400 amp load then you will have to calculate it but you are ignoring some info the others are giving you.
- Location
- New Jersey
- Occupation
- Journeyman Electrician
Dennis, can you explain wht this means? I see the mentioned often and have no idea how this applies to a service. If the calcuated load is 399 amps can I use the 400 amps meter base?
- Location
- Massachusetts
This is the basic voltage drop formula.
Please note;
L=Length
R=Resistance
I=Current
You need to know all three of those items to do the calculation.
You do not seem to have the current so If I assume it is 320 amps and use one of the voltage drop calculators on line and with 120/240 service using 500 AL and a load of 320 amps it seems you can run 260' before you exceed 3% drop.
http://www.electrician2.com/calculators/vd_calculator.html
Considering your load will very likely be much less you have no voltage drop issue to worry about.
- Location
- Massachusetts
Yes you can as the NEC calculated load has already accounted for the continuous and non-continuous loads.
Picture a standard 400 amp panel, in truth it is also rated 320 continuous 400 non-continuous.
jumper
Senior Member
- Location
- 3 Hr 2 Min from Winged Horses
Not sure about that, a 400A panel should be rated at 400A continuous for a SUSE rating IMO. must be a UL thing I guess.
I am talking about a SEC OCPD panel, not a branch circuit or feeder OCPD for a panel.
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