BR vs QO

Status
Not open for further replies.
mcclary's electrical

mcclary's electrical

Senior Member
Location
VA
I did a service change a few weeks ago, I took out an old 30 space QO and put in a 42 circuit BR. The homeowner is saying that the lights "dim" whem the AC kicks on. They swear it never did it before. All connections are tight from service to meter. My question is:

Are the insides of a 200 amp BR "lighter duty" than a 200 amp QO? Smaller contacts?. Maybe have smaller internal wiring? I don't have a spare 200 of each to cut open and look
 
I wonder if the light circuit is on a different phase than it used to be and it's now on a phase that has a developing problem? Maybe you found a problem by luck?

Did you have a chance to check voltages (line-neutral) during the compressor startup?

I like the QOs, but I find it hard to believe they would be that much better.
 
hardworkingstiff said:
I wonder if the light circuit is on a different phase than it used to be and it's now on a phase that has a developing problem? Maybe you found a problem by luck?

Did you have a chance to check voltages (line-neutral) during the compressor startup?

I like the QOs, but I find it hard to believe they would be that much better.
Click to expand...

I was there today, but only to label the panel for her. My label maker was actin g funny the day of service change, so I went back today to label panel, and that was when she told me. I plan on investigating it further, but I was on a tight schedule today.

I too, fi nd it hard to believe that a QO is that much better, but I think it's the only variable here. Although, the lights could have very well been on another phase before the swap.
 
iwire said:
My first thought is the customer is full of it.
Click to expand...

I'm starting to think that. Maybe the slight "dimming" when A/C kicks on has always been there, and

1)they never noticed it or
2) they knew it, and were hoping a service change would stop it or
3) a BR has smaller wire inside, but I doubt it
 
mcclary's electrical said:
I'm starting to think that. Maybe the slight "dimming" when A/C kicks on has always been there, and

1)they never noticed it or
2) they knew it, and were hoping a service change would stop it or
3) a BR has smaller wire inside, but I doubt it
Click to expand...

1) Yea, it's possible because they will watching closely right after the service change.

2) If that's it, ...... wow.

3) I doubt it too.

Please let us know what your investigation uncovers.
 
I doubt very much that the very short busses in a panel would contribute to a voltage drop, and the difference between two panels would be even less of a contributor, I would look more as to the size/type of the conductors used to connect this new panel to the meter/service disconnect, and maybe check these connections, if you suspect the voltage drop is in the service drop/laterals, then a recorder will prove this theory,
but it is possible that one leg of the panel now has a heavier load then it used to, take current readings while everything that would be normally running and see how balanced the service is, if this is the case then sure the extra current put on this leg by the AC can push the voltage drop over the edge, try moving the lights to the other leg and see what happens.
 
I always ask why they think they need a service change, many times other issues come out that have nothing to do with the size of the service.
 
Ken9876 said:
I always ask why they think they need a service change, many times other issues come out that have nothing to do with the size of the service.
Click to expand...

There was an addition put on the house that required (4) new branch circuits. The old panel was a 30 circuit QO, with 37 circuits in it, not rated for tandems, and was full of the Cutler Hammer knock version of QO's. I wasn't about to bring my HR's in it.
 
The only breaker that could conceivably contribute to this issue is the main, and it's my understanding that both SqD lines use the same main breaker now. For a load on one circuit to affect a load on another circuit, it must be caused by something they share, and the last thing in the system is the panel buses.

You can narrow it down by using a quick-responding meter or a 240v bulb and seeing how far up the power chain the voltage-drop-caused dimming occurs. If it's at or ahead of the meter, then it's under the POCO's jurisdiction. Give her their number. The one thing you should explain is that some dimming is normal.
 
LarryFine said:
The only breaker that could conceivably contribute to this issue is the main, and it's my understanding that both SqD lines use the same main breaker now. For a load on one circuit to affect a load on another circuit, it must be caused by something they share, and the last thing in the system is the panel buses.

You can narrow it down by using a quick-responding meter or a 240v bulb and seeing how far up the power chain the voltage-drop-caused dimming occurs. If it's at or ahead of the meter, then it's under the POCO's jurisdiction. Give her their number. The one thing you should explain is that some dimming is normal.
Click to expand...

Thanks Larry. I'll keep you posted
 
Status
Not open for further replies.
Top