ONE FAMILY HOUSE,HOMEOWNER WANT TO MAKE HIS ATTIC INTO AN OFFICE,I HAVE ADDED A SUB PANEL TO ATTIC 60 AMP.HE WANT TO ADD 4 COMPUTERS,I'M USING ISOLATED RECEPTACLES.DO I HAVE TO RUN THE COMPUTER BRANCH CIRCUIT LINES BACK TO THE SERVICE PANEL WHICH IT IS IN THE BASEMENT OR TO THE SUBPANEL,ACCORDING TO 250.146D.
computer receptacle
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petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
Re: computer receptacle
Why waste money on isolated ground receptacles?
if you think for some reason they are needed, the ground has to go back to the service ground bar and not to the subpanel.
since in general the grounds have to be run with the circuit conductors, i'd say if you insist on using Ig receptacles you would need to run the branch circuits from the main panel.
[ January 17, 2005, 10:08 AM: Message edited by: petersonra ]
Why waste money on isolated ground receptacles?
if you think for some reason they are needed, the ground has to go back to the service ground bar and not to the subpanel.
since in general the grounds have to be run with the circuit conductors, i'd say if you insist on using Ig receptacles you would need to run the branch circuits from the main panel.
[ January 17, 2005, 10:08 AM: Message edited by: petersonra ]
Re: computer receptacle
First, please turn off the cap lock key, it is considered rude.
My first question to you is the house wood framed, and/or are you running NM to plastic boxes?
If yes, why in the world would you install IGR, it alraedy is by the nature of the installation. Just use regular receptacles.
First, please turn off the cap lock key, it is considered rude.
My first question to you is the house wood framed, and/or are you running NM to plastic boxes?
If yes, why in the world would you install IGR, it alraedy is by the nature of the installation. Just use regular receptacles.
O
oliver100
Guest
Re: computer receptacle
You can advise the owner to use UPS. He will be isolated from any ground interference.
You can advise the owner to use UPS. He will be isolated from any ground interference.
al hildenbrand
Senior Member
- Location
- Minnesota
- Occupation
- Electrical Contractor, Electrical Consultant, Electrical Engineer
Re: computer receptacle
It is also important to assure the various unrelated conductive grounded systems (pipe, telco, cable, structured media center, etc) are bonded to the Grounding Electrode System of the electrical service.
Look at </font>
I agree that the use of battery backup power supplies is valuable, but they don't, by themselves, minimize problems on the equipment ground.
It is also important to assure the various unrelated conductive grounded systems (pipe, telco, cable, structured media center, etc) are bonded to the Grounding Electrode System of the electrical service.
Look at </font>
- <font size="2" face="Verdana, Helvetica, sans-serif">250.94 & 250.104</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">800.40(B)(1)</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">810.21(F)</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">820.40(B)(1)</font>
stud696981
Senior Member
Re: computer receptacle
I would have to agree with dereckbc. There will probably not be a need for an isolated ground.
When it comes to computers in residential, I have found very few issues if everything is wired properly..........and there is good grounding and bonding, including phone, catv, etc. Most of the problems I have seen when things are wired correctly are simply another device in the house causing interference (cheap components or defective), or more commonly a cheap, poorly manufactured PC.
Unless your client has some type of highly sensitive computer system, I would recommend a normal install and skip the IG plugs. However, I would recommend he purchase a quality UPS for each computer.
I would have to agree with dereckbc. There will probably not be a need for an isolated ground.
When it comes to computers in residential, I have found very few issues if everything is wired properly..........and there is good grounding and bonding, including phone, catv, etc. Most of the problems I have seen when things are wired correctly are simply another device in the house causing interference (cheap components or defective), or more commonly a cheap, poorly manufactured PC.
Unless your client has some type of highly sensitive computer system, I would recommend a normal install and skip the IG plugs. However, I would recommend he purchase a quality UPS for each computer.
Re: computer receptacle
All, there is as much miss-conception about UPS as there is about grounding. UPS systems come in three basic flavors; stand-by, interactive, and dual conversion.
Stand-by UPS that you find used in most homes are the inexpensive types you see in computer and other box stores for the $100-to-$250 price range. These are very simple devices that have a small battery charger, battery, and inverter. In normal operation, the line is connected directly to the load without any form of isolation. If you put garbage in, you will get garbage out. In the event of a power failure, a relay switches the output to the inverter and the battery takes over for a short period of time.
Going up in price is the ?interactive? type UPS which does have some isolation via a static transformer. It still uses a small battery charger and inverter, but the inverter stays active to correct any voltage variations on the output sort of like a buck-n-boost transformer. In the event of a power failure the inverter takes over without any relay control, whereas a stand-by type has to switch which takes time and some occurrence is felt on the output. Prices for interactive type UPS start around $400 and go up with KVA, bells, and whistles.
The third type, ?dual conversion? is the Cadillac and most expensive of the units. These types are what are used in Data centers and can go up to 750 KVA. A dual conversion unit are rectifiers rated for the full output load rating plus enough reserve to charge the batteries in as little as 4-hours, batteries, and inverter. The inverter is on line 100% of the time giving complete isolation from line to load, or input to output. So the process flow in a dual conversion unit is AC-to-DC-to-AC. Units for home use start around $600-$800.
So IMHO advising someone to install a UPS to clean up power is miss-leading if a stand-by type is used.
All, there is as much miss-conception about UPS as there is about grounding. UPS systems come in three basic flavors; stand-by, interactive, and dual conversion.
Stand-by UPS that you find used in most homes are the inexpensive types you see in computer and other box stores for the $100-to-$250 price range. These are very simple devices that have a small battery charger, battery, and inverter. In normal operation, the line is connected directly to the load without any form of isolation. If you put garbage in, you will get garbage out. In the event of a power failure, a relay switches the output to the inverter and the battery takes over for a short period of time.
Going up in price is the ?interactive? type UPS which does have some isolation via a static transformer. It still uses a small battery charger and inverter, but the inverter stays active to correct any voltage variations on the output sort of like a buck-n-boost transformer. In the event of a power failure the inverter takes over without any relay control, whereas a stand-by type has to switch which takes time and some occurrence is felt on the output. Prices for interactive type UPS start around $400 and go up with KVA, bells, and whistles.
The third type, ?dual conversion? is the Cadillac and most expensive of the units. These types are what are used in Data centers and can go up to 750 KVA. A dual conversion unit are rectifiers rated for the full output load rating plus enough reserve to charge the batteries in as little as 4-hours, batteries, and inverter. The inverter is on line 100% of the time giving complete isolation from line to load, or input to output. So the process flow in a dual conversion unit is AC-to-DC-to-AC. Units for home use start around $600-$800.
So IMHO advising someone to install a UPS to clean up power is miss-leading if a stand-by type is used.
Re: computer receptacle
Yes, forget the IG receptacles.
Properly bonded & grounded (earthed) system will power this "computer" equipment just fine.
IMO, someone would really have to have a good reason to install an IG receptacle, especially if wired with "Romex".
It is not 1982 anymore. The IG recept. fad (fiasco) is over.
Yes, forget the IG receptacles.
Properly bonded & grounded (earthed) system will power this "computer" equipment just fine.
IMO, someone would really have to have a good reason to install an IG receptacle, especially if wired with "Romex".
It is not 1982 anymore. The IG recept. fad (fiasco) is over.
O
oliver100
Guest
Re: computer receptacle
derckbs - You are quite right. Stand-by UPS is no good.
On some navy ships I've seen 120/120 isolated transformers for the receptacles of the radio and other radar equipment rooms. One such transfromer would be a possible and not expensive solution for the owner, I think.
derckbs - You are quite right. Stand-by UPS is no good.
On some navy ships I've seen 120/120 isolated transformers for the receptacles of the radio and other radar equipment rooms. One such transfromer would be a possible and not expensive solution for the owner, I think.
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