Voltage drops

John G. Merritt

Ran into a job yesterday that showed a voltage drop from normal 120 voltage to Heating circuit to 70 Volts, also the
24 volt transformer showed only 13 volts!
I am not an electrician, so I'm not sure what will cause this. Anybody help me out here?
It's a standard hydronic system with 4 wall relays (for 4 unit heaters) 1 circulator and a stack control, and 1 zone valve.
John

John G. Merritt

Voltage Drops

Ran into a job yesterday that showed a voltage drop from normal 120 voltage to Heating circuit to 70 Volts, also the
24 volt transformer showed only 13 volts!
I am not an electrician, so I'm not sure what will cause this. Anybody help me out here?
It's a standard hydronic system with 4 wall relays (for 4 unit heaters) 1 circulator and a stack control, and 1 zone valve.
John

J.C.A.

Do the lights dim...

and flicker when the heat tries to come on ? Had this happen 1 time and found a very loose neutral wire in the panel .Was not making contact every time and all the lights would flicker . Hope this helps . Chris

John G. Merritt

Lighrts do not dim

Chris,
The lights do not dim when the burner starts.
The problem is with the Heating circuit only.
Everything else shows 120 volts.

John

JimGPE_3

Sounds like a

fire waiting to happen!!! You are losing a LOT of voltage somewhere, and that means a LOT of heat. Shut it down and find an electrician immediatly!

J.C.A.

I agree

with Jim .

John G. Merritt

Voltage drop

Jim,

I did tell the customer to call an Electrician.
I would really like to know what causes this, and it's the first time I have run into this sort of thing.
Any ideas?

John

Steamhead

Bad connection somewhere

could be at one of the servicing or emergency switches. Pretty easy to find the problem if you know what to look for. But I agree if you're not comfortable with this, call in an electrician.

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Bob C.

This happened to me

This happened to me last year and come to find out the transformer for the whole street was bad and it had to be replaced. The ho said he replaces the light bulbs in his house all the time. I just put in as new boiler and was doing the start up when I noticed it. Called Eletric CO.

John Jr

Check your grounds!

A bad ground will do that. Had that problem before told the electrician what the problem was and he laugh at me! I got the last laugh when the electrical company showed up to fix the bad ground on the pole.

John Jr

Bob Tonner

Voltage drop

It sounds like the drop is caused by a poor connection somewhere. If there is a loose connection (say at the base of a screw-in fuse) then there will be some heat build-up. Over time this heat build-up will cause corrosion, pitting and carbon build-up. This will lead to more voltage-drop and the cycle continues until a catastrophic fault occurs.

My recommendation is to check the base of the fuse (if applicable) and all other wiring points in the circuit. A loose wire nut will also cause the problem.

Best regards,

Bob Tonner, President, InfinityLab Inc.

billygoat22

is the wire gauge large enough for load and the distance? I like to replace ungrounded circuits anyway if I can, especially if its old and accesible

John G. Merritt

Voltage drop reply

Thanks guys for all your input. I hope this customer does what I told him to do and get an Electrician.
Company proceedure is not to go into Electrical Panels.
When you have an open ground, isn"t the line hot back to that point at a lower voltage? I can't remember exactly but i think that is correct.

John

Tom_53

low voltage

I had a similar call this past summer. This circut was going out to the pool heater and was protected by a groumd fault circut breaker. Replaced the breaker & voltage went back to normal from about 70v. I am not a master elect. I do not normally open breaker boxes but this call was at a relitives house.
From Jack

Frank_3

Well, you've gotten plenty of replies all ready but I'll add my 2 cents.

I had a similar problem which was caused by the previous owner using the wrong brand of circuit breaker in the panel. The breaker didn't seat quite right and was silently arcing until over time the heat being produced started to melt the breaker and wear away the contacts. That caused the voltage problem, which luckily I spotted before a fire got started. Three other surrounding breakers were also starting to melt though they weren't showing any arcing damage on their own -- they were the right brand and seated properly.

So, as has been stated already, get an electrician to that customer right away or tell them to shut down the breaker and look for problems in the panel or with connections between the panel and the boiler room. Since the wire running to the boiler room is most likely a direct run the only other connection point (besides the breaker) would be at the shut-off switch in or near the boiler room.

Oh, and if I didn't make it clear for anyone reading, if you have a Murray circuit breaker panel, use only Murray breakers. Got a GE panel? Use GE breakers. Same goes for any other breaker/panel manufacturer. They may look the same and sort of fit the same, but they are different.

Kevin_2

Check for an open neutral.

Kevin_2

Check for an open neutral.

Duncan_2

I've seen that too.

> Well, you've gotten plenty of replies all ready

> but I'll add my 2 cents.

>

> I had a similar

> problem which was caused by the previous owner

> using the wrong brand of circuit breaker in the

> panel. The breaker didn't seat quite right and

> was silently arcing until over time the heat

> being produced started to melt the breaker and

> wear away the contacts. That caused the voltage

> problem, which luckily I spotted before a fire

> got started. Three other surrounding breakers

> were also starting to melt though they weren't

> showing any arcing damage on their own -- they

> were the right brand and seated properly.

>

> So,

> as has been stated already, get an electrician to

> that customer right away or tell them to shut

> down the breaker and look for problems in the

> panel or with connections between the panel and

> the boiler room. Since the wire running to the

> boiler room is most likely a direct run the only

> other connection point (besides the breaker)

> would be at the shut-off switch in or near the

> boiler room.

>

> Oh, and if I didn't make it clear

> for anyone reading, if you have a Murray circuit

> breaker panel, use only Murray breakers. Got a

> GE panel? Use GE breakers. Same goes for any

> other breaker/panel manufacturer. They may look

> the same and sort of fit the same, but they are

> different.

Duncan_2

Bad breaker or bad neutral...

Probably the most likely culprits. I've seen the bad breaker problem. Good calls.

Another possibility is that the boiler circuit is wired in series with something else. If the boiler is is on its own circuit like it's supposed to be, that shouldn't happen. I'd start at the circuit breaker.

The transformer secondary has only half the voltage or so, 13 volts, because its INPUT is at only half the voltage (roughly), 70 volts.