# Service size for Chiropractic Office: X-Ray



## Wardey (Mar 11, 2009)

I'm a little rusty...I have been out of the trade for over 10 years !!! LOL


----------



## RePhase277 (Feb 5, 2008)

You better get the nameplate data from the machine. I don't know what kind of x-rays he's making, but a 100 A machine sounds on the high side to me.


----------



## JohnJ0906 (Jan 22, 2007)

Wardey said:


> First time poster here and with a question. Thank you in advance !!!
> 
> Trying to size a service for a chiropactors office and not sure on the demand for an X-Ray machine. The X-Ray Tech say's he needs an 100 Amp 220V circuit. Here's what I have existing:
> 100 Amp 3 Phase Service w/ 1 Alum Conductors
> ...


If it is a 3 phase service, you probably have 208Y/120volts, not 240.

Where are you getting 3 VA per square foot from? Offices are 3.5 per sqft, also, check 220.14(K) for the receptacle calc.


----------



## Wardey (Mar 11, 2009)

correct. My Bad, sorry. It is a 120/208 Delta Y


----------



## JohnJ0906 (Jan 22, 2007)

Wardey said:


> correct. My Bad, sorry. It is a 120/208 Delta Y


I presume you mean Y if it is 208/120.
240/120 would be a high leg Delta


----------



## Wardey (Mar 11, 2009)

correct.


----------



## JohnJ0906 (Jan 22, 2007)

You might want to get more info on that X-ray machine to find out what the actual load is, as opposed to the circuit size. And also check Article 660.

Also, don't forget to increase continuous loads to 125%



Personally, if that X-ray takes a 100 amp circuit, I wouldn't connect it to a 100 amp service. Sell them an upgrade.


----------



## Kevin J (Dec 11, 2008)

I'd really check the rating of that X-ray if I were you. I just recently provided power for a panoramic X-ray in a dental office, and it called for a 120V/20A circuit. This isn't the small arm X-ray units located by each chair either.


----------



## Chris Kennedy (Nov 19, 2007)

InPhase277 said:


> You better get the nameplate data from the machine. I don't know what kind of x-rays he's making, but a 100 A machine sounds on the high side to me.


About average size for a chest X-ray type gizmo.


----------



## pjg (Nov 11, 2008)

look at art 517 Part V. The power comsumed by an xray is very quick as in milliseconds, I've wired a few units in the past but I can't remmber the demand load on the service . look at 517.73 A(2) makes me think 50% demand. It seem that you will need a nameplate or manual for sure.


----------



## randas (Dec 14, 2008)

100a? wow. Last time I did a dental x-ray it was only [email protected]


----------



## micromind (Aug 11, 2007)

A lot of X-ray machines I've connected in hospitals are 100 amp, 480 volt. As stated above, the continuous load is only a couple of amps, but when in operation the load can be over 100 amps for a very short time. 

Most of the more knowledgeable X-ray techs I talk to say the large service is needed more for wire size than anything else. 

I don't think I'd put a 100 amp X-ray machine on a 100 amp service to a building unless the service is dedicated to that machine, no lights or other stuff. You'd notice the lights dim. 

Rob


----------



## rlc3854 (Dec 30, 2007)

640 sq ft is a pretty small space for a medical office with x-ray capabilities. Your probably looking at a small stand up chest type of unit. If it is an older unit 50 amp disconnect single phase. New unit 20 amp dedicated single phase circuit.

2002 NEC 517.73

(1) Branch Circuits. The ampacity of supply branch-circuit conductors and the current rating of overcurrent protective devices shall not be less than 50 percent of the momentary rating or 100 percent of the long-time rating, whichever is greater.
(2) Feeders. The ampacity of supply feeders and the current rating of overcurrent protective devices supplying two or more branch circuits supplying X-ray units shall not be less than 50 percent of the momentary demand rating of the largest unit plus 25 percent of the momentary demand rating of the next largest unit plus 10 percent of the momentary demand rating of each additional unit. Where simultaneous biplane examinations are undertaken with the X-ray units, the supply conductors and overcurrent protective devices shall be 100 percent of the momentary demand rating of each X-ray unit.
FPN:The minimum conductor size for branch and feeder circuits is also governed by voltage regulation requirements. For a specific installation, the manufacturer usually specifies minimum distribution transformer and conductor sizes, rating of disconnecting means, and overcurrent protection.


----------



## 76nemo (Aug 13, 2008)

rlc, after somebody had thee audacity of posting about "One guy sitting on a jar" tonight, I'll never think of you the same with that avatar.:001_huh:


----------



## rlc3854 (Dec 30, 2007)

76nemo said:


> rlc, after somebody had thee audacity of posting about "One guy sitting on a jar" tonight, I'll never think of you the same with that avatar.:001_huh:


Yea, I need to find a new one now that it is spring and time to get my head out of my arse:laughing:


----------

