# What is a loop?



## Dash Dingo

I am an inside wireman and I'm wiring a brand new building. I don't have power from the poco yet. I was told that it is going to be a while because its a loop.
Don't know what that means.


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## 480sparky

Overhead: AKA Drip Loop. A sag in the conductor just before it enters the weatherhead... prevents water from running along wires into weatherhead.

Underground : AKA Frost Loop. Extra direct-burial cable in a shepherd's hook/bo-peep shape to allow for movement of the conductors/raceway sleeve/ground in areas with frost.

A loop also may mean the POCO brings power through an area in a circle. They start out at point A, the run to ponts B, C, D, E, F, etc. then back to point A and dead-end it there. That way, if there's a problem in the future, the POCO can disconnect the affected portion of the circle and energize the otherwise-disconnected end of the loop from the dead-end at point A.


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## RIVETER

Dash Dingo said:


> I am an inside wireman and I'm wiring a brand new building. I don't have power from the poco yet. I was told that it is going to be a while because its a loop.
> Don't know what that means.


I am an inside wire man and have never heard of that terminology.


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## Dash Dingo

RIVETER said:


> I am an inside wire man and have never heard of that terminology.


It has something to do with the way the poco is going to tie into the power around the area. It's all underground. I was told that they have to tie into a loop, so it's going to be a while before I get power to the building.


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## Big John

It's a double-ended distribution circuit, which means it's fed from two directions. They probably have to install a sectionalizer for your building so you can be isolated in the event of a fault, and I'd bet that's what's taking time.

-John


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## big2bird

RIVETER said:


> I am an inside wire man and have never heard of that terminology.


There are three ways to distribute power. Radial, loop, or network.


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## B4T

Big John said:


> It's a double-ended distribution circuit, which means it's fed from two directions. They probably have to install a sectionalizer for your building so you can be isolated in the event of a fault, and I'd bet that's what's taking time.
> 
> -John


They use that system so they can take a trans. out of service and still keep the other trans. on that feed live..


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## 480sparky

B4T said:


> They use that system so they can take a trans. out of service and still keep the other trans. on that feed live..


Or a damaged section of cable...... and still keep power up and running for those with the checkbooks. 

The POCO can then make the repairs at a later time instead of dealing with an issue immediately (i.e., an emergency repair).


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## big2bird

B4T said:


> They use that system so they can take a trans. out of service and still keep the other trans. on that feed live..


That's one of many reasons.


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## 480sparky

Don't the Brits wire houses with the same principle?


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## etb

Another meaning of loop, at least here, is the service drop or lateral to the meter. Doesn't have anything to do with drip loop, as it also applies to underground. If you call to schedule a service change they'll ask for the new billing address to move an account to; instead you have to ask for a new loop.



480sparky said:


> Don't the Brits wire houses with the same principle?


Called ring circuits in the UK and elsewhere, but it's to increase circuit ampacity, not for redundancy. They also have "spurs" off the rings.


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## TOOL_5150

etb said:


> Another meaning of loop, at least here, is the service drop or lateral to the meter. Doesn't have anything to do with drip loop, as it also applies to underground. If you call to schedule a service change they'll ask for the new billing address to move an account to; instead you have to ask for a new loop.
> 
> 
> 
> Called ring circuits in the UK and elsewhere, but it's to increase circuit ampacity, not for redundancy. They also have "spurs" off the rings.


is the circuit really a ring, do they connect both conductors to the OCP?


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## 480sparky

TOOL_5150 said:


> is the circuit really a ring, do they connect both conductors to the OCP?



I would think you'd have to.

I've seen the same principle used in lighting circuits, especially in large buildings like auditoriums and the like. Cuts down on VD and provides much more even lighting.


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## etb

TOOL_5150 said:


> is the circuit really a ring, do they connect both conductors to the OCP?


Hear ye, hear ye, read all about it.
Get your copy now, free-pence each, or three for two.

http://en.wikipedia.org/wiki/Ring_circuit



480sparky said:


> I've seen the same principle used in lighting circuits, especially in large buildings like auditoriums and the like. Cuts down on VD and provides much more even lighting.


You've seen it in the US?


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## 480sparky

etb said:


> ........You've seen it in the US?


Installed a couple. I think they also do airport runway lights that way, too.


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## nolabama

Big John said:


> It's a double-ended distribution circuit, which means it's fed from two directions. They probably have to install a sectionalizer for your building so you can be isolated in the event of a fault, and I'd bet that's what's taking time.
> 
> -John


And this is an example of what can make HV extra deadly. Which way is it fed from and is that the only way it's fed was one of the first things I was taught.


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## etb

480sparky said:


> Installed a couple. I think they also do airport runway lights that way, too.


I think code-wise it'd be impossible to reduce conductor size. Ie, I think lower VD / more even distribution in the loop are the only benefits here in US.

Never worked on RW lights, but a guy who did told me they were 480V but didn't mention anything about ring.



nolabama said:


> And this is an example of what can make HV extra deadly. Which way is it fed from and is that the only way it's fed was one of the first things I was taught.


It also makes it more difficult to set the protection relays.


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## sbrn33

480sparky said:


> Overhead: AKA Drip Loop. A sag in the conductor just before it enters the weatherhead... prevents water from running along wires into weatherhead.
> 
> Underground : AKA Frost Loop. Extra direct-burial cable in a shepherd's hook/bo-peep shape to allow for movement of the conductors/raceway sleeve/ground in areas with frost.
> 
> A loop also may mean the POCO brings power through an area in a circle. They start out at point A, the run to ponts B, C, D, E, F, etc. then back to point A and dead-end it there. That way, if there's a problem in the future, the POCO can disconnect the affected portion of the circle and energize the otherwise-disconnected end of the loop from the dead-end at point A.


Actually they don't dead end it. They hook up both ends to the supply.


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## etb

sbrn33 said:


> Actually they don't dead end it. They hook up both ends to the supply.


Sometimes, sometimes not. Even if connected with a switch, switch is often left open.


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## zeeshan kha

unknown


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