# 5th terminal



## electricalperson

I feel horribly stupid but i never had to install a 5th terminal in a meter socket. Seeing the term in another thread got me thinking, Whats the purpose of this and when do we need to do it? I see the terminals for sale in my milbank catalogs but i never had to install it and dont know when i will ever have too.


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## 480sparky

It's so you can run 208v from a 3-phase system through a single-phase meter. Without it, the meter will not be accurate.

I've heard 'em called '5th jaw', 'ticklers' and 'bastards'.


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## electricalperson

thank you ken. i feel less stupid now. its pretty amazing how much i DONT know. it goes to show how large this trade is


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## davis9

Yeah, always look at the street side and check for 120/208 or 120/240. Working in the same city it changes from street to street depending on proximity to businesses etc.

Got caught a couple times without it and the POCO wouldn't set the meter.

Tom


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## electricalperson

100% of the residential services ive worked on around here were just regular 4 terminal 120/240V single phase. all 3 phase services ive done were underground with a 13 terminal CT meter socket


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## user4818

It will always be a poco spec or requirement to use a 5th terminal.


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## davis9

electricalperson said:


> 100% of the residential services ive worked on around here were just regular 4 terminal 120/240V single phase. all 3 phase services ive done were underground with a 13 terminal CT meter socket



It will be needed on a 120/208 single phase service.

Tom:thumbsup:


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## electricalperson

thanks everyone


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## electricalperson

all new services i will do i'll call up nstar and ask exactly what they want. i done plenty for the contractor i worked for just never did any on my own yet.


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## BBQ

electricalperson said:


> 100% of the residential services ive worked on around here were just regular 4 terminal 120/240V single phase. all 3 phase services ive done were underground with a 13 terminal CT meter socket


If you do single, double family homes in parts of Boston and Cambridge you would run into it. They run a 3 phase 4 wire network around the neighborhood and just alternate which two legs to supply single phase to the homes. The homes end up with 208/120 single phase.

It also shows up in large apartment buildings with 3 phase services but single phase feeders to each unit.


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## HARRY304E

electricalperson said:


> I feel horribly stupid but i never had to install a 5th terminal in a meter socket. Seeing the term in another thread got me thinking, Whats the purpose of this and when do we need to do it? I see the terminals for sale in my milbank catalogs but i never had to install it and dont know when i will ever have too.


http://www.nstar.com/business/service_requirements/docs/elecrequire.pdf
NSTAR BLUE BOOK..*&ELECTRIC SERVICE*


CUSTOMERS
ELECTRICIANS
ARCHITECTS
ENGINEERS
BUILDERS
INSPECTORS​​*INFORMATION & REQUIREMENTS *​

​​​​​​*FOR ELECTRIC SERVICE*​

*IMPORTANT INFORMATION FOR*
*ELECTRICIANS*​

Revised 2009​



*METER SOCKETS*
​​*715. Meter Sockets for Self-Contained Meters*
Approved sockets for self-contained meters must be listed for the
use by a recognized testing agency. See section A of this article
for more specific details. To insure the accurate registration of
energy usage, the meter socket must be of the proper type that
matches the installed service from NSTAR’s distribution
system.
*A. Sockets with Manual Bypass*
All non-residential and common area meter applications
shall have sockets with manual bypasses. Bypasses are
required to permit a meter change without customer service
interruption with the following requirements:
1. Horn and automatic bypasses are not permitted.
2. NSTAR approved single-handle, manually operated,
LOCKING jaw manual lever by-pass (commercial grade)
with safety arc shields are required on all services. For
services 100 amperes or less a non-locking manual lever
by-pass is acceptable.
3. After the meter is installed and the bypass handle is in the
down position (not in bypass position), the mechanism
must be visible in the open position with the cover off.
4. It must not be possible to replace the meter socket cover
when the handle is in the bypass position.
5. A manual bypass is not to be used as a service disconnect.
*B. 200 Amperes or Less*
Self-contained socket metering is standard practice on single
phase and three phase installations where the service
capacity is not greater than 200 amperes and the voltage is
not greater than 480 volts.
All 480 volt, 3 wire and 4 wire sockets shall be equipped
with acceptable safety arc shields. A disconnect is required
ahead of and in close proximity to each meter socket and
shall be within sight of the meter socket (cold sequence). If
the disconnect switch is not visible at the meter location
then it must be a lockable device.
The following is a list of socket type metering requirements for
services rated 200 amperes or less:
1. Single phase, 3 wire, 120/240 volt service: A 4 terminal
meter socket is acceptable, except for residential services
in Boston (Downtown/network area), Cambridge,
Charlestown, a 5th terminal. (See Sketches 17 and 18)
2. Single phase, 3 wire, 120/208 volt service: A 5
terminal meter socket is required. (See Sketches 17
and 18)​

_85_​ 


_*S*_​

_*KETCH 19*_

_*Meter Installation for 200 Amperes, Three Phase, 3 Wire, 240 or*_

_*480 Volt Service With 5 Terminal Meter Socket and Bypass*_
_*Meter Installation for 200 Amperes, Three phase, 4 Wire, 120/208 or*_
_*277/480 Volt Service With 7 Terminal Meter Socket and Bypass*_
_LINE_
_LOAD_
_BY-PASS_
_LEVER IN_
_BY-PASSING_
_POSITION_
_COMMON PHASE_
_CONNECTION_
_5th_
_TERMINAL_
_LINE_
_LOAD_
_SERVICE_
_NEUTRAL_
_BONDED TO_
_BOX_
_SERVICE_
_NEUTRAL_
_N_
_BY-PASS_
_LEVER IN_
_BY-PASSING_
_POSITION_
_A B C_
_N A B C_
_*1. COMMON PHASE CONNECTION MUST BE INSULATED*_
_*FROM THE SOCKET.*_
_On Three Phase Delta only A & C phases are bypassed; B phase is_
_always energized and 5th terminal permanently attached at 6 o’clock_
_position._
_2. Drain hole in the bottom of meter socket must be punched out._
_3. A manual, single handled bar with locking jaw bypass and safety arc_
_shield is required._
_4. 5th Terminal located at 6 o’clock._
_1. Drain hole in the bottom of meter socket must be punched out._
_2. A manual, single handled bar with locking jaw by-pass and safety arc_​
​


_shield is required_​​​


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## HARRY304E

That starts on page 84 or the NSTAR BOOK and the meter sketches are on page 129

I could not get the sketch page to copy right.:blink:


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## thegoldenboy

My cities POCO requires us to install them on the left side on any new installations. I don't know the price difference but it's something I may just do out of habit, required or not. It can't be substantial enough to break the bank in taking 2 minutes in installing it.


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## TOOL_5150

BBQ said:


> If you do single, double family homes in parts of Boston and Cambridge you would run into it. They run a 3 phase 4 wire network around the neighborhood and just alternate which two legs to supply single phase to the homes. The homes end up with 208/120 single phase.
> 
> It also shows up in large apartment buildings with 3 phase services but single phase feeders to each unit.


Why would someone want a 120/208 service to their house, when most appliances run at 120 or 240v?


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## 480sparky

TOOL_5150 said:


> Why would someone want a 120/208 service to their house, when most appliances run at 120 or 240v?



It's not that they _want_ it..... that's all that is available from the POCO. Many appliances are dual rated for use with either voltage.


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## BBQ

HARRY304E said:


> That starts on page 84 or the NSTAR BOOK and the meter sketches are on page 129
> 
> I could not get the sketch page to copy right.:blink:


What you have decided is a drain hole, is per the manufacturer a hole for the GEC.


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## electricalperson

you all are really helpful


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## BBQ

TOOL_5150 said:


> Why would someone want a 120/208 service to their house, when most appliances run at 120 or 240v?


If the want power they take what they can get, household appliances are dual rated ..... but it will take longer to boil water on the stove at 208 vs 240.


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## MDShunk

TOOL_5150 said:


> Why would someone want a 120/208 service to their house, when most appliances run at 120 or 240v?


If you live in a neighborhood with a network service, you don't really have a choice. They'll put a big transformer someplace and run a big ring around the neighborhood and drop off the taps to each home.


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## TOOL_5150

running a 240v stove is going to take more current running at 208, so the circuit may have to be sized up to compensate then.


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## TOOL_5150

MDShunk said:


> If you live in a neighborhood with a network service, you don't really have a choice. They'll put a big transformer someplace and run a big ring around the neighborhood and drop off the taps to each home.


Guess thats the cheap way the poco does it huh? Here, we have transformers every 8 houses or so.


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## BBQ

TOOL_5150 said:


> Guess thats the cheap way the poco does it huh? Here, we have transformers every 8 houses or so.


On my street that is how it is done.

But in the city that is a bit of a problem, where are you placing all these transformers?


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## BBQ

TOOL_5150 said:


> running a 240v stove is going to take more current running at 208, so the circuit may have to be sized up to compensate then.


Have another beer and think about that.


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## TOOL_5150

BBQ said:


> On my street that is how it is done.
> 
> But in the city that is a bit of a problem, where are you placing all these transformers?


Here, they place em in vaults in peoples yards. the transformer I am on is across the street in my neighbors yard. in the older neighborhoods, they got pole pigs everywhere.


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## MDShunk

TOOL_5150 said:


> Guess thats the cheap way the poco does it huh? Here, we have transformers every 8 houses or so.


No. It's the only way in highly congested areas like downtowns and historical areas. It's actually a benefit, since they most often double end feed these setups with a tie switch someplace. The downside is that it can be especially difficult to arrange an outage to do work on a network service.


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## BBQ

TOOL_5150 said:


> Here, they place em in vaults in peoples yards. the transformer I am on is across the street in my neighbors yard. in the older neighborhoods, they got pole pigs everywhere.


In these areas there are no yards, there are no poles.

The large network transformers have to be buried under the street or sidewalks.

I think you will find this is a fairly common thing in densely packed city neighborhoods.


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## MDShunk

BBQ said:


> In these areas there are no yards, there are no poles.
> 
> The large network transformers have to be buried under the street or sidewalks.
> 
> I think you will find this is a fairly common thing in densely packed city neighborhoods.


Right. People don't really realize that when they're walking down a sidewalk and they walk over a couple big metal plates that look like they might go down into a building's basement, they're either walking over the transformer vault or one of the tap vaults. On a side note, if I ever become homeless, I'm living in a tap vault. They have light fixtures, panels, and sump pumps. :jester:


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## Electric_Light

BBQ said:


> It also shows up in large apartment buildings with 3 phase services but single phase feeders to each unit.


you really don't even need to see the electrical room to have a pretty good guess if its got a three phase service or not. The complex doesn't have to be large. 

Since single phase elevators are rare, if it's got an elevator, you can basically assume its got three phase service.

People don't like moving furniture and appliances up stairs and with ADA codes these days, even small complexes usually have at least one elevator these days.


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## TOOL_5150

BBQ said:


> In these areas there are no yards, there are no poles.
> 
> The large network transformers have to be buried under the street or sidewalks.
> 
> I think you will find this is a fairly common thing in densely packed city neighborhoods.


That is pretty dense if they cant even have yards.. must suck to live there.


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## MDShunk

Electric_Light said:


> you really don't even need to see the electrical room to have a pretty good guess if its got a three phase service or not. The complex doesn't have to be large.
> 
> Since single phase elevators are rare, if it's got an elevator, you can basically assume its got three phase service.


Probably a good guess, but I've seen enough buildings where the owner panel is on a 3-phase drop, and the tenant stack is fed with a big single phase service. Never assume.


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## BBQ

Electric_Light said:


> you really don't even need to see the electrical room to have a pretty good guess if its got a three phase service or not. The complex doesn't have to be large.


Most electricians are quite capable of determining the difference between single and three phase services.:laughing:



> Since single phase elevators are rare, if it's got an elevator, you can basically assume its got three phase service.


That kind of assuming will bite you in the ass.:thumbsup:


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## Electric_Light

MDShunk said:


> Probably a good guess, but I've seen enough buildings where the owner panel is on a 3-phase drop, and the tenant stack is fed with a big single phase service. Never assume.


Well, if it's got three phase for elevator or centralized chiller, tenant units are gonna have 208/120 unless they go through the trouble of 208 to 120/240 transformer or the service is 240 delta or they have separate services entirely.



> That kind of assuming will bite you in the ass.:thumbsup:


True. Should have phrased it "pretty good guess" there too.


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## BBQ

TOOL_5150 said:


> That is pretty dense if they cant even have yards.. must suck to live there.


Not my idea of a home.

http://maps.google.com/maps?f=q&sou...1472,-71.07796&spn=0.008103,0.021136&t=h&z=16


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## HARRY304E

BBQ said:


> What you have decided is a drain hole, is per the manufacturer a hole for the GEC.


Ah no i did not,, take a look at a 200amp meter socket there is a drain hole punch jost to the right side of the 2" KO in the back bottom of the pan there is a punch that is about 1/8" they want you to punch that out you would be lucky to fit a #8 conductor through that hole...


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## BBQ

HARRY304E said:


> Ah no i did not,, take a look at a 200amp meter socket there is a drain hole punch jost to the right side of the 2" KO in the back bottom of the pan there is a punch that is about 1/8" they want you to punch that out you would be lucky to fit a #8 conductor through that hole...


Harry, I am not going to continue this game, as Dennis mentioned the manufactures identify that small KO as a spot for the GEC.

They do not ship 3R equipment with drain holes that are closed, if the drain holes are closed it is not 3R.


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## MDShunk

The drain holes are already there. In the back two corners.


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## thegoldenboy

BBQ said:


> They do not ship 3R equipment with drain holes that are closed, if the drain holes are closed it is not 3R.


We, in MA, are allowed to punch out that 1/4" KO for the GEC and rightfully call it a drain hole. 

2011 MA 314.15 

So Harry is kinda sorta right if you sit there and justify it long enough.


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## HARRY304E

BBQ said:


> Harry, I am not going to continue this game, as Dennis mentioned the manufactures identify that small KO as a spot for the GEC.
> 
> They do not ship 3R equipment with drain holes that are closed, if the drain holes are closed it is not 3R.


Oh ok so Nstar is stupid and all the Electrical inspectors as well.

Call NSTAR and ask the your self by what they mean on page 128 in the PDF .

NSTAR the Electrical inspector and me are aware of the factory drain holes at the corners they want the one in the middle right hand side punched as well.

BTW


*230.50 Protection Against Physical Damage.*​
*(A) Underground Service-Entrance Conductors. *
Underground
service-entrance conductors shall be protected
against physical damage in accordance with 300.5.​​*(B) All Other Service-Entrance Conductors. *​*
*​*
*All other
service-entrance conductors, other than underground ser
vice entrance conductors, shall be protected against physical​damage as specified in 230.50(B)(1) or (B)(2).

*(1) Service-Entrance Cables. *​*
*​*
*Service-entrance cables,
where subject to physical damage, shall be protected by any
of the following:
(1) Rigid metal conduit
(2) Intermediate metal conduit
(3) Schedule 80 PVC conduit
(4) Electrical metallic tubing
(5) Reinforced thermosetting resin conduit (RTRC)
(6) Other approved means​​*(2) Other Than Service-Entrance Cables. *​*
*​*
*Individual open
conductors and cables, other than service-entrance cables,
shall not be installed within 3.0 m (10 ft) of grade level or
where exposed to physical damage.​​_Exception: Type MI and Type MC cable shall be permitted_
_within 3.0 m (10 ft) of grade level where not exposed to_
_physical damage or where protected in accordance with_​
_300.5(D)._
​​​​
So it looks like you can not use the 1/4 KO for your GEC that is no game it is the NEC...-​​​​​


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## BBQ

HARRY304E said:


> Oh ok so Nstar is stupid and all the Electrical inspectors as well.


No, I am saying the manufactures know better what the hole is for than N-Star ....... or are you telling me NStar is well run?:jester:

I am also saying the manufactures could not get a 3R listing with blocked up drain holes.:thumbsup:


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## HARRY304E

BBQ said:


> No, I am saying the manufactures know better what the hole is for than N-Star ....... or are you telling me NStar is well run?:jester:


Nope not at all as they say it rolls down hill from NSTAR to the inspectors to the Electricians


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## user4818

MDShunk said:


> No. It's the only way in highly congested areas like downtowns and historical areas. It's actually a benefit, since they most often double end feed these setups with a tie switch someplace. The downside is that it can be especially difficult to arrange an outage to do work on a network service.



The other downside is massive amounts of available fault current. In my area, U/G network services require a disconnect ahead of the meter (cold sequence?)

I know of someone who had a blow up in a network fed service panel. It was not pretty at all.


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## MDShunk

Peter D said:


> The other downside is massive amounts of available fault current. In my area, U/G network services require a disconnect ahead of the meter (cold sequence?)
> 
> I know of someone who had a blow up in a network fed service panel. It was not pretty at all.


You're absolutely right.


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## user4818

MDShunk said:


> You're absolutely right.


I will certainly never rise to your level of genius, but of all the stupid things I say, occasionally I get something right. :laughing:


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## MDShunk

Peter D said:


> I will certainly never rise to your level of genius, but of all the stupid things I say, occasionally I get something right. :laughing:


As they say, even a blind squirrel gets a nut once in a while.


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## user4818

MDShunk said:


> As they say, even a blind squirrel gets a nut once in a while.


Right. Which is why I was blessed with good looks, charm, and wit. :jester:


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## Electric_Light

Peter D said:


> The other downside is *massive amounts of available fault current*. In my area, U/G network services require a disconnect ahead of the meter (cold sequence?)
> 
> I know of someone who had a blow up in a network fed service panel. It was not pretty at all.


Speaking of which, more and more switching power supplies of all sizes(AC adapters, IT equipment, electronic ballasts, etc etc) incorporates a means of inrush current limiting. Some were suffering high rate of failures in the field even though they tested durability test in the lab. 

It was noted in the paper that this was attributed higher inrush current blowing front end rectifier bridge and degrading bulk storage caps due to lower source impedance in the field than the service feeding the testing lab.


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