QO120MH breaker for small x-ray unit

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Ohms law said:
Is the QO120MH acceptable replacement for a slow action fuse?

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IMO, No. A breaker is not a fuse, their time current curves are likely not very close.
But you are correct, it maybe necessary to use a QO120HM to feed a device that has a relatively high inrush, but even then it it likely to go instantaneously at 8-10x.
 
I downloaded photo bucket. How do I post a link for a photo? I would like someone to look at the power requirements and give an opinion.

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Henry Shein, supplier of the dental equipment gave us specs for a 120vac 20amp branch circuit with nothing about fuses required for equipment.

Now that the equipment is installed and we have the manufactures documentation, it states "Fuse at the distribution panel" 20amp, 120vac,slow
Then goes on saying the maximum current rating of the x-ray unit is momentary and refers you to 517.73(a)(1) for sizing of branch circuit and disconnect.

Henry Shein has given us 3 different specs and really has left us hanging.

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Ohms law said:
I downloaded photo bucket. How do I post a link for a photo? I would like someone to look at the power requirements and give an opinion.

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Open a photobucket account, upload your photo. When viewing an individual photo there will be options for sharing, one of them is IMG code. click on that and it will copy the code to your clipboard, and in the place you want to place that image within your post, paste the IMG code. It will display the code when you are composing your post but after you submit it that code gets replaced with the image when anyone is viewing the post. May be some exceptions if someone has firewall settings or browser settings blocking it, but will show for most people. If you remove the image from photobucket, then the IMG code will be pointing to an invalid address and there will be no image shown.

I also agree that you probably want to use a QO120HM breaker.
 
kwired said:
Open a photobucket account, upload your photo. When viewing an individual photo there will be options for sharing, one of them is IMG code. click on that and it will copy the code to your clipboard, and in the place you want to place that image within your post, paste the IMG code. It will display the code when you are composing your post but after you submit it that code gets replaced with the image when anyone is viewing the post. May be some exceptions if someone has firewall settings or browser settings blocking it, but will show for most people. If you remove the image from photobucket, then the IMG code will be pointing to an invalid address and there will be no image shown.

I also agree that you probably want to use a QO120HM breaker.
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I think I still need to install a fused disconnect or get approval from Henry Shein for a QO120MH breaker instead if fused disconnect.

The fact it doesn't state fuse/ breaker and only says "fused at the distribution panel, means I have to be fused, wouldn't this be correct?

Wait a second, how do I become fused at the distribution panel when it is a QO panel? Any thoughts. Out of 5 electrical inspectors, this specific one is the worst to deal with. He is always an A-hole.

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Ohms law said:
I think I still need to install a fused disconnect or get approval from Henry Shein for a QO120MH breaker instead if fused disconnect.

The fact it doesn't state fuse/ breaker and only says "fused at the distribution panel, means I have to be fused, wouldn't this be correct?

Wait a second, how do I become fused at the distribution panel when it is a QO panel? Any thoughts. Out of 5 electrical inspectors, this specific one is the worst to deal with. He is always an A-hole.

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If it calls for a fuse, you about need to install a fused disconnect, somewhere. Or find an old FSP Loadcenter:blink:

I guess I was assuming at first there was trouble holding the magnetic trip on a regular QO breaker and therefore the need for something with a higher magnetic trip. This generally only a problem with QO single pole breakers though as they have a low magnetic trip setting, the concept of one of their ideas of "quick - open" a phrase they used for marketing, but it only is that way for their single pole 15 and 20 (and possibly 30) amp standard breakers.
 
I think I'm going to have to go to a fuse disconnect.
I'll find out Monday if the inspector will approve.
He originally wanted 10awg ran since the nameplate said 21.3 amps. Article 517.73a1 states momentary sized to 50%. He didn't agree.

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Regardless of what the inspector says, if you don't get permission from the manufacturer to use a breaker after they have specked a fuse and something goes wrong you will own the machine.

The fused disconnect seems to be your best bet.

Roger
 
I agree. I just want to have all my information to help the customer. The GC had a supervisor that was a drunk who has really screwed up on 3 dental offices that I'm running.

Needless to say he has been fired and I want to help the dentist open her business. Her project was suppose to last 4 months and it has been 6 months.

Thank you all once again for clarity.

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Ohms law said:
I think I'm going to have to go to a fuse disconnect.
I'll find out Monday if the inspector will approve.
He originally wanted 10awg ran since the nameplate said 21.3 amps. Article 517.73a1 states momentary sized to 50%. He didn't agree.

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Is 21.3 the momentary rating or the long time rating? If long term rating I think you do need 10AWG. Otherwise the greater value of:100% of long term rating or 50% of short term rating.

I'm not a medical equipment expert, but dental X-ray machines may not even have a long term rating. Seems that would apply more to CT scanners.
 
kwired said:
Is 21.3 the momentary rating or the long time rating? If long term rating I think you do need 10AWG. Otherwise the greater value of:100% of long term rating or 50% of short term rating.

I'm not a medical equipment expert, but dental X-ray machines may not even have a long term rating. Seems that would apply more to CT scanners.
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The equipment literature said the maximum current rating is momentary.

The inspector just saw a nameplate that said 21.3amps. What I'm worried about is it also says fused at the distribution panel. That is my only concern now, It can not be accomplished with a single phase QO panel.

I'll try to present this information to the inspector and see what he says. That's all I can do. At least I can say it is not.my fault and I tried to do what I could.

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Ohms law said:
The equipment literature said the maximum current rating is momentary.

The inspector just saw a nameplate that said 21.3amps. What I'm worried about is it also says fused at the distribution panel. That is my only concern now, It can not be accomplished with a single phase QO panel.

I'll try to present this information to the inspector and see what he says. That's all I can do. At least I can say it is not.my fault and I tried to do what I could.

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What fuse rating and type does it call for?
 
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AFAIK "slow" isn't normally a used as fuse type designation, they probably do want some time delay characteristic, but still left it wide open with "slow".

Plug fuses - S and T are fairly common, cartridge fuses - they should specify RK1, RK5, J....

I think more verification from the equipment provider is necessary
 
kwired said:
AFAIK "slow" isn't normally a used as fuse type designation, they probably do want some time delay characteristic, but still left it wide open with "slow".

Plug fuses - S and T are fairly common, cartridge fuses - they should specify RK1, RK5, J....

I think more verification from the equipment provider is necessary
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This is by far the worst experience with medical supply company I have had. The plans originally stated a 240vac, 20amp outlet and then came back and said that the Canada and US version is only 120vac.

I will have to call Monday to get approval to provide for inspector saying we can use a breaker. I really don't have anywhere to mount a fused disconnect anyway.

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Ohms law said:
This is by far the worst experience with medical supply company I have had. The plans originally stated a 240vac, 20amp outlet and then came back and said that the Canada and US version is only 120vac.

I will have to call Monday to get approval to provide for inspector saying we can use a breaker. I really don't have anywhere to mount a fused disconnect anyway.

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Let me guess, made in an Asian country?
 
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