Originally Posted By: jonofrey This post was automatically imported from our archived forum.
The lights of the masterbathroom dimmed momentarily every time the hydro-therapy tub motor was kicked on. I understand that the motor will draw more amps on start up than once it is running and this can rob amps from other devices on the circuit.
Originally Posted By: bbadger This post was automatically imported from our archived forum.
jonofrey wrote:
My question is:
Is this just a nuisance or is there more to it?
99% chance it is just a nuisance.
The short instant that the power is applied to the motor but it is not yet rotating is called locked rotor.
The locked rotor current is quite high, six times running current would not be unusual.
A motor that takes 10 amps running could easily draw 60 amps at start up, the instant the motor starts turning the current falls rapidly.
With this high of a current draw it is difficult to wire building in a way that it goes unnoticed.
The human eye is very good at noticing a just a few volts of drop on an incandescent lamp.
I was just working on a 500 HP electric motor yesterday, if this motor was brought on line directly it would dim the entire area around this facility.
Its running current is about 600 amps @480 volt 3 PH, it's locked rotor current would be about 3600 amps. 
The way around this is the use of a speed control to wind it up slowly, in this case about 5 minutes to get this motor and the fan it drives up to speed.
It would be possible to use a 'soft start' device on a small motor like that in the hydro tub but they are expensive.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: bbadger This post was automatically imported from our archived forum.
Joe must you find fault with everything?
Is nothing normal?
One can only wonder how the entire country is getting by without you riding shotgun on every inspection. 
When was the last time you actually worked with tools and not a book.
Its called street smarts and you can not find it in a book.
-- Bob Badger
Electrical Construction & Maintenance
Moderator at ECN
Originally Posted By: jonofrey This post was automatically imported from our archived forum.
Joe,
I guess the answers are yes and yes. One year builders warranty inspection. All the neutral conductors were terminated under single screw terms on the neutral bus. I assumed that the tub motor was connected to the lighting circuit but I don't know that for sure.
The system ground clamp was loose but I tightened it since I was there and had a screwdriver.
Originally Posted By: jtedesco This post was automatically imported from our archived forum.
bbadger wrote:
Joe must you find fault with everything?
Is nothing normal?
One can only wonder how the entire country is getting by without you riding shotgun on every inspection. 
When was the last time you actually worked with tools and not a book.
Its called street smarts and you can not find it in a book.
Originally Posted By: jtedesco This post was automatically imported from our archived forum.
jonofrey wrote:
Joe,
I guess the answers are yes and yes. One year builders warranty inspection. All the neutral conductors were terminated under single screw terms on the neutral bus. I assumed that the tub motor was connected to the lighting circuit but I don't know that for sure.
The system ground clamp was loose but I tightened it since I was there and had a screwdriver.
Thanks John: That may have been some of the problem.
Originally Posted By: rcooke This post was automatically imported from our archived forum.
It could be the suppliers fault I did a home last week 200 amp service fed from the road with # ten I guess some time ago it had a much smaller service and has been upgraded maybe more the once . It could be a simple as upgrading the incoming lines.
There are also other things that could cause it to many homes on too small a supply transformer . To far away from the transformer .
It is some times impossible to get the full answer here as many things can be part of the problem . I to find it hard to inspect from a picture as you do not get all the information .
Thanks Joe Tedesco I sure do appreciate your feed back much appreciated . From A retired Sparky started the trade in 1951
In Canada some things are done just a little differently
Originally Posted By: bsmith This post was automatically imported from our archived forum.
Bob-
Thanks for your reply. The light dimmed only in one room (which I suspect was on the same circuit as the motor). The motor was a small pool pump which seemed to be plugged into a general use 15 amp circuit. Could the cause of the dimming be as simple as the motor drawing too much current from that circuit?
-- Bill Smith
www.SmithHomeInspection.com
"The difference between stupidity and genius is that genius has its limits." A. Einstien