Wire size.

[sigma]

There is a need to run copper wires for electric heater. The heater will be three phase, 208 V 37 A.
Can #8 gauge be used or the distance of 150 feet to the breaker panel would require #6 gauge?

[DavidDeBord]

My immediate response is to go #6, but, ...... That is without doing any Calculations sigma.

[Ptierneysunset]

There is a need to run copper wires for electric heater. The heater will be three phase, 208 V 37 A.
Can #8 gauge be used or the distance of 150 feet to the breaker panel would require #6 gauge?

1.73 x 208 = 359.84

359 x 37 = 13,283 watts

# 6 for sure

[JustinCrow]

Thanks for the help buddy. Even I was looking for help.

[David Goodman]

Wire type (Temp. Rating) and ambient temperature are important as well as the length.

[DavidDeBord]

Wire type (Temp. Rating) and ambient temperature are important as well as the length.

Indeed David.

[COOLJIM]

1.73 .. ?

[gustavhorna]

you have about 130W loss on 37A with 150ft #8 wire (if 3 phase then per phase), imo far too much

[Juan Madera]

Its own conduit or in an already populated conduit? Gotta consider fill too.

[VTP99]

.

[BBeerme]

Here, I got a good one for you . . .

A buddy, also in our trade, increased his 100 A single phase service to his house up to a 200 A service.

The utility company installed 8 gauge wire. He called and complained to the code enforcement officials. After it was all said and done, yes, you can run 200 amps on 8 gauge wire that is in open air. At least according to that utility company. Code enforcement officer was satisfied with the utilities companies 'report'.

My friend wanted to be able to use an electric welder without dimming the lights. His wife hated that. There was probably still some dimming, but the wifey was happy, and last I heard, no problem with the small gauge of wire.

Its own conduit or in an already populated conduit? Gotta consider fill too.

[gustavhorna]

Here, I got a good one for you . . .

A buddy, also in our trade, increased his 100 A single phase service to his house up to a 200 A service.

The utility company installed 8 gauge wire.

in that case the utility company pays for the losses on the line... as it is before the meter (well at some point they will push these costs onto all customers as increased kwh price), however in the second case the home owner pays for the losses on the cables that are after the meter - so yes size matters

[DavidDeBord]

Here, I got a good one for you . . .

A buddy, also in our trade, increased his 100 A single phase service to his house up to a 200 A service.

The utility company installed 8 gauge wire. He called and complained to the code enforcement officials. After it was all said and done, yes, you can run 200 amps on 8 gauge wire that is in open air. At least according to that utility company. Code enforcement officer was satisfied with the utilities companies 'report'.

My friend wanted to be able to use an electric welder without dimming the lights. His wife hated that. There was probably still some dimming, but the wifey was happy, and last I heard, no problem with the small gauge of wire.

I installed a 200A Underground service for a Modular, & South Central Power was the Utility (No Inspections required other than their Own.), .... They provided the URD for the Service, & started throwing #2 in the trench, & I asked the foreman, "What th' Hale R U Doing?". This Yahoo told me that "it'll be fine,... No Big Deal.", & I told him that I had an Inspector coming from Clermont County,& that I wanted 4/0 URD in the trench.

This guy began complaining about having to drive all the way back to Hillsboro & getting the wire, so, ... I called the Inspector, & he got on the phone with this Yahoo, & told him, that he wasn't allowed to use #2 URD on a 200A install.

Needless to say, the Yahoo *****ed about it, but he went & got the 4/0 Al, ... And the Inspection passed.

How your buddy got by with #8 Tri-plex baffles me BBeerme.

[DavidDeBord]

in that case the utility company pays for the losses on the line... as it is before the meter (well at some point they will push these costs onto all customers as increased kwh price), however in the second case the home owner pays for the losses on the cables that are after the meter - so yes size matters

I Agree Gust.

But more Importantly, ..... The "Strut" is Extremely Important, & BBeerme can fill you in about that.

YEAH!!!! Ah! Ah! Ah!Ah!,... Stayin' Alive!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

[BBeerme]

Keep in mind, since it was from the pole to the service panel, the utility company installed it.

I installed a 200A Underground service for a Modular, & South Central Power was the Utility (No Inspections required other than their Own.), .... They provided the URD for the Service, & started throwing #2 in the trench, & I asked the foreman, "What th' Hale R U Doing?". This Yahoo told me that "it'll be fine,... No Big Deal.", & I told him that I had an Inspector coming from Clermont County,& that I wanted 4/0 URD in the trench.

This guy began complaining about having to drive all the way back to Hillsboro & getting the wire, so, ... I called the Inspector, & he got on the phone with this Yahoo, & told him, that he wasn't allowed to use #2 URD on a 200A install.

Needless to say, the Yahoo *****ed about it, but he went & got the 4/0 Al, ... And the Inspection passed.

How your buddy got by with #8 Tri-plex baffles me BBeerme.

[DavidDeBord]

Keep in mind, since it was from the pole to the service panel, the utility company installed it.

I understand, but, .... Per Annex B, Page 70-701, Table B.310.15B(2)(3) of the 2017 NEC

#8 Copper's high rating is only 59 Amps at 194 degrees F., & if it's Al., then it's lower.

In my "Humble Opinion" , ... The "Utility" Fubared the situation.

[BBeerme]

I don't know the code, but I do know you need to find the table that rates wire size for open air conditions. If I'm not mistaken, my buddy did find that table, and was quite surprised how much current a wire can carry when it can freely dissipate the heat.

I understand, but, .... Per Annex B, Page 70-701, Table B.310.15B(2)(3) of the 2017 NEC

#8 Copper's high rating is only 59 Amps at 194 degrees F., & if it's Al., then it's lower.

In my "Humble Opinion" , ... The "Utility" Fubared the situation.

[DavidDeBord]

I don't know the code, but I do know you need to find the table that rates wire size for open air conditions. If I'm not mistaken, my buddy did find that table, and was quite surprised how much current a wire can carry when it can freely dissipate the heat.

What I quoted, unless I'm severely mistaken is for "Open Air", ... Can you get the Reference from your Buddy, for me, BBeerme?

[BBeerme]

No, he's long gone. Retired to Hawaii, haven't heard from him since.

Keep in mind, it was probably a real short run as well. And he never had a problem with it.

Kinda makes you wonder if the wire was even insulated.

What I quoted, unless I'm severely mistaken is for "Open Air", ... Can you get the Reference from your Buddy, for me, BBeerme?

[shellkamp]

I understand, but, .... Per Annex B, Page 70-701, Table B.310.15B(2)(3) of the 2017 NEC

#8 Copper's high rating is only 59 Amps at 194 degrees F., & if it's Al., then it's lower.

In my "Humble Opinion" , ... The "Utility" Fubared the situation.

I believe the utility company isn't bound by the NEC, and can (and do) run their conductors as hot as they care to.

That being said, I am surprised #8 was chosen and even more surprised that a welder was run off of it. :Grin:

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