Service entrance cable - Type SE - NEC 338.10

[Neybomb26]

My friend did run seu from the meter into the house no more than 3 feet then back out of the house. His question was is that legal. I gave him a couple of code articles that mite be useful in his situation.

 

[don_resqcapt19]

Probably a union thing. Chicago must wire a house in emt.... I personally don't like se cable running exposed as it seems to me it is always likely to be damaged. You don't see it around here unless it is an old install but it is compliant

No code rule is ever a "union" thing unless you are saying the non-union guys can't install the wiring methods that the code requires.

 

[don_resqcapt19]

That does not answer my question. is it just to increase the cost?

Because the old SE did not do well with sun light, may services are in areas where the service conductors are subject to physical damage, and the fire department wanted metal around the service conductors.

 

[electrofelon]

Because the old SE did not do well with sun light, may services are in areas where the service conductors are subject to physical damage, and the fire department wanted metal around the service conductors.

I have certainly seen SE cable with the jacket degraded away, but it was also probably 60 years old and I don't think PVC would last any longer, plus after that long even in RGS the insulation at the drip loop the would be crumbling by then.

 

[infinity]

A good friend of mine asked me real good question that I didn't have a solid answer for. He was doing a battery backup system on a house and he had no choice but to enter the house from the load side of the meter then run the se a short distance (less than 5 feet) then exit tge house to land in the transfer switch. I think the issue is that there's no over current protection after the se enters the biulding

The distance into the house isn't based on any particular wiring method. You cannot run RMC further into the house than you can SE cable, they both have the same limit.

 

[Ravenvalor]

This topic reminds me of a question that has been nagging me all week.
A small tree fell on the local POCO's overhead service conductors feeding a home. Both of the attachment points held the overhead service conductors in place because the tree was not big enough to rip either one of them out of their mooring. However, the bare grounded wire was burnt in two. About 5' away from where the tree made contact to the overhead service conductors it appeared that the bare grounded wire cut into the old insulation of one of the insulated non-grounded conductors and burnt itself in two. What's been nagging me is why didn't a fuse at the transformer open? I shared my concerns with the customer and asked them to call the utility.

 

[augie47]

This topic reminds me of a question that has been nagging me all week.
A small tree fell on the local POCO's overhead service conductors feeding a home. Both of the attachment points held the overhead service conductors in place because the tree was not big enough to rip either one of them out of their mooring. However, the bare grounded wire was burnt in two. About 5' away from where the tree made contact to the overhead service conductors it appeared that the bare grounded wire cut into the old insulation of one of the insulated non-grounded conductors and burnt itself in two. What's been nagging me is why didn't a fuse at the transformer open? I shared my concerns with the customer and asked them to call the utility.

Few possible reasons:
Likely not a sufficient enough current... more of an arcing fault
The fuse is there to protect the transformer, not the secondary
Some POCOs are not real selective on sizing the primary fusing (what's on the truck is fine)

 

[don_resqcapt19]

Few possible reasons:
Likely not a sufficient enough current... more of an arcing fault
The fuse is there to protect the transformer, not the secondary
Some POCOs are not real selective on sizing the primary fusing (what's on the truck is fine)

In many cases the fuse is not even sized to protect the transformer, but only sized to prevent the next upstream device from opening.

 

[tom baker]

Are you sure Tom? Check the WAC, it appears the restriction is only for service conductors "within" a building or structure. I see no restriction for EMT or SE cable on the outside of a building or structure.

I had to look, thanks, SE cable is not allowed within as you pointed out. However, I have not seen SE cable used outside anywhere in WA. Now I wonder why not?

 

[MD Automation]

Few possible reasons:
Likely not a sufficient enough current... more of an arcing fault
The fuse is there to protect the transformer, not the secondary
Some POCOs are not real selective on sizing the primary fusing (what's on the truck is fine)

Have to agree w/ Augie (and Don). Last year when I watched my Poco (BGE) replace my failed 25 kVA transformer, I saw them replace the cutout with this 10DI fuse...



Looking up the data on that fuse shows it would pass 20A for 5 minutes before opening. Looks like it would let thru 10 or 15A forever.




This is a 7680 Primary, that's a 32:1 ratio on the windings, so it could supply something like 300 to 600 amps on the secondary without clearing a "fault". Way enough time (and heat) to burn thru an overhead or underground secondary conductor that was arcing.

They clearly are trying to minimize nuisance tripping and protect against only the most severe overloads.

Want that fuse to open in 1 sec? It's going to take at least 100A. On the primary.

 

[electrofelon]

I had to look, thanks, SE cable is not allowed within as you pointed out. However, I have not seen SE cable used outside anywhere in WA. Now I wonder why not?

I have never seen it in WA either. Note that the Seattle Electrical code and the cities Electrical code (used by many other cities) do not allow SE for services at all. You would have to be in a jurisdiction where neither of those two mentioned codes apply and only the WAC applies to use SE for outside service conductors.

 

[Ravenvalor]

Have to agree w/ Augie (and Don). Last year when I watched my Poco (BGE) replace my failed 25 kVA transformer, I saw them replace the cutout with this 10DI fuse...

View attachment 2556866

Looking up the data on that fuse shows it would pass 20A for 5 minutes before opening. Looks like it would let thru 10 or 15A forever.

View attachment 2556865


This is a 7680 Primary, that's a 32:1 ratio on the windings, so it could supply something like 300 to 600 amps on the secondary without clearing a "fault". Way enough time (and heat) to burn thru an overhead or underground secondary conductor that was arcing.

They clearly are trying to minimize nuisance tripping and protect against only the most severe overloads.

Want that fuse to open in 1 sec? It's going to take at least 100A. On the primary.

Would not that be a fire hazard if a spark landed on the ground and ignited dry pine needles, brush, grass or anything?