Temping Out Panel

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Alwayslearningelec

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Estimator
So I may have to temp out the secondary side(of xfrmr) panel while we shut down to disconnect/reconnect.

What would be the most practical way to temp the panel out? Thanks

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So the panel you want to temp out is 208Y/120? Then you'll also need a 480-208Y/120 volt transformer?
 
What is being disconnected/reconnected and what is it you wish to power while down? Keep in mind you are likely losing power at least for short time regardless.
 
electrofelon said:
Could you provide some details? I'm not really clear what you are trying to do.
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We are changing out transformers and the primary and secondary feeds(which are all less than 10' in length). The panel that's fed by the secondary side may not be able top be de-energized( if so not for long at all). So I'm thinking I may need to temp out this panel but not sure what temp power source I would use.
 
Alwayslearningelec said:
We are changing out transformers and the primary and secondary feeds(which are all less than 10' in length). The panel that's fed by the secondary side may not be able top be de-energized( if so not for long at all). So I'm thinking I may need to temp out this panel but not sure what temp power source I would use.
Click to expand...
I have connected a temporary feed in parallel, just using some SER or MC cable, and then disconnected the original feed, thus having no loss of power at all. Obviously that involves hot work and weather that is feasible will depend on who is doing the actual work. Of course it could be not hot with just a minute or two outage also. Is there another panel near by? Simplest would be to come off of a 100A breaker if there is space available.
 
Alwayslearningelec said:
We are changing out transformers and the primary and secondary feeds(which are all less than 10' in length). The panel that's fed by the secondary side may not be able top be de-energized( if so not for long at all). So I'm thinking I may need to temp out this panel but not sure what temp power source I would use.
Click to expand...
You will need a 208/120 source and it will need to be shut down long enough to connect the temp supply and reconnect the permanent supply.

one possibility is back feed a breaker with a temp supply and you can possibly lessen down time or eliminate it altogether if you are in phase with the original supply. (if you are not in phase it probably going down anyway though) This is easier if you can keep expected load at a minimum level and use say a 100 amp or less back feed breaker vs 150-225 or whatever is there. What you may have for hot work rules and such need consideration as well.
 
This is an extension of THIS THREAD.
It may be a little more involved than just finding a close 208/120V source. It might be supplying conductors from an ATS to the electrical closet(s). The design engineer should be participating in the planning.
 
Alwayslearningelec said:
We are changing out transformers and the primary and secondary feeds(which are all less than 10' in length). The panel that's fed by the secondary side may not be able top be de-energized( if so not for long at all). So I'm thinking I may need to temp out this panel but not sure what temp power source I would use.
Click to expand...
So you'll need to find a panel to get the 208 volt temp feeder from assuming that there actual is one. As Roger pointed out you might need to get the engineer involved depending on the loads.
 
electrofelon said:
I have connected a temporary feed in parallel, just using some SER or MC cable, and then disconnected the original feed, thus having no loss of power at all. Obviously that involves hot work and weather that is feasible will depend on who is doing the actual work. Of course it could be not hot with just a minute or two outage also. Is there another panel near by? Simplest would be to come off of a 100A breaker if there is space available.
Click to expand...
That is unknown if there's a spare breaker. I parallel you mean while it's live you run another feed from your temp source to the panel ytou are temping out? Where would land the conductors if the panel lugs are already used by the existing?
 
kwired said:
You will need a 208/120 source and it will need to be shut down long enough to connect the temp supply and reconnect the permanent supply.

one possibility is back feed a breaker with a temp supply and you can possibly lessen down time or eliminate it altogether if you are in phase with the original supply. (if you are not in phase it probably going down anyway though) This is easier if you can keep expected load at a minimum level and use say a 100 amp or less back feed breaker vs 150-225 or whatever is there. What you may have for hot work rules and such need consideration as well.
Click to expand...
Thank you. What does back feed exactly mean? What electro was referring to when he said running temp in parallel?
 
Alwayslearningelec said:
That is unknown if there's a spare breaker. I parallel you mean while it's live you run another feed from your temp source to the panel ytou are temping out? Where would land the conductors if the panel lugs are already used by the existing?
Click to expand...
In a perfect world the panel you are supplying from temporarily, and the new panel will have or have space for a triple 100 breaker, which is going to be fine for a 200 amp panel most of the time. If not you can cob the temp feed under the main lugs or use some IPC's.
 
Since the existing feeder is from a transformer you may be limited in where a 208 volt feeder is available. You could end up with a temp transformer if only 480 is available.
 
Alwayslearningelec said:
Thank you. What does back feed exactly mean? What electro was referring to when he said running temp in parallel?
Click to expand...
By backfeeding a breaker (if there is space available to install one) you can make the connection with temp conductors "off" but panel still "on". Worst case you can turn off the normal supply and turn the temp breaker on and only be down for just a second or so. If you are certain you are in phase with both sources you could have both on at same time before turning original feed off, if there is absolutely no way you can shut down for some reason otherwise I'd still rather turn off original feed then turn on temp feed even though it causes a brief outage. 100 amp breaker was mentioned simply because it is easier to come up with than say a 200 that will plug on to most panels intended to take miniature type breakers and was assuming/hoping you have or can reduce loading to below 100 amps for the duration of this change over.
 
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